But, we have ways to make the antenna's talk. Maybe you have read or heard about the CFA antenna's being tested in Egypt and the UK. What are CFA's? Crossed field antennas. Only 2% of a wavelength in size, nearly 100% efficiency, setting up the electric and magnetic fields in a much different way. That's right. And one of the benefits of the way the fields are set up is that EMI is virtually eliminated. I didn't typo here. And, as a broadcast engineer I think a 500 foot radiator (or 160 feet, or yagi's, towers and the like ) is a thing of beauty, and you should have at least a quarter wave vertical with a good ground system to radiate properly, setting up the electric and magnetic fields according to how Mr. Hertz back in the 1880's developed the basic antenna we all have used. All these details can be found by going to the www.eh-antenna.com site. Far more detail and explanation than I will put here, so check out the site to find out more. Also, Jack, W0KPH has done a lot of work with the EH types of antenna's (very successfully). Go to http://www.qsl.net/w0kph/ I have talked with Jack at length and am very excited about the design.
To that end, I constructed w0kph's 20-meter antenna and tested it out. Fellow amateurs: I was as amazed as you are about to be. My test antenna was made out of a cardboard mailing tube 14 inches long and 2 inches wide.

As you will see when you visit the websites, the cylinders you see in the picture are made out of aluminum foil, the coil and link for the coax are covered in electrical tape made out of #22 wire to hold them in place after adjustment, and the antenna was put on a broomstick about 3 feet above the floor in my basement shack/laundry room. This is about 3 feet below ground level. The measurements to start with and full description with pictures are all on the w0kph web page. I then proceeded to trim the coil back about half a turn from the original 15 turns, and adjusted the link (where the coax connects) to where I started to hear signals on my TS-120. Then, testing with power applied, I got a 2 to 1 match, and then with more, down to 1.3 to 1. WOW I thought, it takes power. And, the signals I can hear were about an S unit to 1 1/2 units below what the dipole outside was hearing. I thought, well, I am below ground level here. A little more adjustment and I got the match flat, and I was hearing W6XX in the San Francisco area with a signal just barely below that of the dipole. Now, one of the things noticed too was that the noise level present on the dipole of about S3 was practically non existent on the EH. Again, I was in the basement with the antenna less than 3 feet away from the clothes dryer and about 8 feet away from me and the radio, but the low noise level of this antenna is intrinsically low due to the way the E field (electric) and H fields (magnetic) are generated. And because the frequency range of the circuit is small, the EH Antenna harmonic radiation is all but nonexistent, but the bandwidth is wider than a conventional Hertz antenna. This from the www.eh-antenna.com website written by Ted Hart, but my experience would indicate that this is so.
So, I thought, here goes nothing. W6XX closed down his QSO and I gave him a call. HE CAME BACK to me and we proceed to exchange the usual signal reports, he gave me a 55-57 report while he was S7-8. I couldn't believe it. I was floored! (Or below the main floor in the basement) We had a 20-minute QSO, and discussed the antenna. He was skeptical as you would expect and probably you yourself are. I was too. Now, I still want to get the EH antenna outside and up in the air for further testing, but I believe it will perform as Ted Hart of the www.eh-antenna.com website and Jack, www.qsl.net/w0kph have had antenna's perform.
And, unbelievable, but folks have constructed a 160 meter antenna only about 6 to 8 feet tall that works incredibly, and the 10 meter version is 5 to 6 INCHES long, and 1 inch in diameter, made out of PVC pipe. That is the next one I will build to put up against the 10-meter vertical dipole. Check these out. They really do work. I will be putting up more information and details as I have time to work on them. If you get to try some of these for yourself, email W0KPH and myself and let us know how they work for you.
73' KE0VH
| ZL1CLG | 2005-02-16 | |
|---|---|---|
| RE: Small EH Antenna | ||
| Actually it was VK5BR. Reply to a comment by : ZL1CLG on 2005-01-24 I build one of these EH antennas for 40m and it works great. I got the plans off the web from VK4BR. It even has a 1:1 swr according to my meter. I think I was very lucky with my adjusting of the capacitors. It turns out to be very touchy with just 1 millimeter making a very big difference. It stays within 1.2 swr over about 100khz. Can anyone explain what radiation efficiency is? It seems to me that if there is no reflected power than all the energy going into the antenna is being radiated, otherwise the thing would be getting hot, which it isn't. Doesn't that mean 100% radiation efficiency (or nearly). Lots of experts are saying that the EH antenna is "hogwash" but I'm not so sure. Maybe the real problem is that nobody knows how it works. Reply to a comment by : VE7SRF on 2004-10-10 Ok, Yesterday I finally slapped together one of these guys and set it up for 40 meters. It was just and experiment, so I used an expended paper roll tube about 2inches dia. Some foil and coils of wire. I hooked up my noise bridge and got it to resonate on 40meters. I was eager to get it on the air, so I didn't even fine tune the vswr with the tap and source coil. Simply used my tuner to load it up and make my rig happy. On goes the power with the paper tube sitting on my desk. I was elated to hear loud clear signals on forty meters from this taped together tube that looked like something left over from a Christmas party. Ok, now I stuck it outside my door on top of a fence post about four feet off the ground. I made two quick qso's with California stations and I'm a VE7 station. S5 - S7 reports. Remember, four feet off the ground, and only 3 feet long on Fory meters, all that and I havn't even had the patience to set it up the with simple tap and source coil described on the eh-antenna web site. I am very encouraged and will be building a proper one before long if I can stay off the air with my existing tube long enough to build a proper one. I am sure the eh antenna system will have a wonderful future as people begin to understand its concept more and more. 73 | ||
| ZL1CLG | 2005-01-24 | |
|---|---|---|
| RE: Small EH Antenna | ||
| I build one of these EH antennas for 40m and it works great. I got the plans off the web from VK4BR. It even has a 1:1 swr according to my meter. I think I was very lucky with my adjusting of the capacitors. It turns out to be very touchy with just 1 millimeter making a very big difference. It stays within 1.2 swr over about 100khz. Can anyone explain what radiation efficiency is? It seems to me that if there is no reflected power than all the energy going into the antenna is being radiated, otherwise the thing would be getting hot, which it isn't. Doesn't that mean 100% radiation efficiency (or nearly). Lots of experts are saying that the EH antenna is "hogwash" but I'm not so sure. Maybe the real problem is that nobody knows how it works. Reply to a comment by : VE7SRF on 2004-10-10 Ok, Yesterday I finally slapped together one of these guys and set it up for 40 meters. It was just and experiment, so I used an expended paper roll tube about 2inches dia. Some foil and coils of wire. I hooked up my noise bridge and got it to resonate on 40meters. I was eager to get it on the air, so I didn't even fine tune the vswr with the tap and source coil. Simply used my tuner to load it up and make my rig happy. On goes the power with the paper tube sitting on my desk. I was elated to hear loud clear signals on forty meters from this taped together tube that looked like something left over from a Christmas party. Ok, now I stuck it outside my door on top of a fence post about four feet off the ground. I made two quick qso's with California stations and I'm a VE7 station. S5 - S7 reports. Remember, four feet off the ground, and only 3 feet long on Fory meters, all that and I havn't even had the patience to set it up the with simple tap and source coil described on the eh-antenna web site. I am very encouraged and will be building a proper one before long if I can stay off the air with my existing tube long enough to build a proper one. I am sure the eh antenna system will have a wonderful future as people begin to understand its concept more and more. 73 | ||
| VE7SRF | 2004-10-10 | |
|---|---|---|
| Small EH Antenna | ||
| Ok, Yesterday I finally slapped together one of these guys and set it up for 40 meters. It was just and experiment, so I used an expended paper roll tube about 2inches dia. Some foil and coils of wire. I hooked up my noise bridge and got it to resonate on 40meters. I was eager to get it on the air, so I didn't even fine tune the vswr with the tap and source coil. Simply used my tuner to load it up and make my rig happy. On goes the power with the paper tube sitting on my desk. I was elated to hear loud clear signals on forty meters from this taped together tube that looked like something left over from a Christmas party. Ok, now I stuck it outside my door on top of a fence post about four feet off the ground. I made two quick qso's with California stations and I'm a VE7 station. S5 - S7 reports. Remember, four feet off the ground, and only 3 feet long on Fory meters, all that and I havn't even had the patience to set it up the with simple tap and source coil described on the eh-antenna web site. I am very encouraged and will be building a proper one before long if I can stay off the air with my existing tube long enough to build a proper one. I am sure the eh antenna system will have a wonderful future as people begin to understand its concept more and more. 73 | ||
| KC0KBH | 2004-08-11 | |
|---|---|---|
| RE: Small EH Antenna | ||
| I just talked to W0KPH the other day on psk, he was using an EH antenna he built, and he was coming in better than the people who had 4 or 5 element yagi's pointed my way. Reply to a comment by : IK5IIR on 2004-02-02 Hi, yes.... I decided to highlight here your last sentence: One must prove for oneself not the word of any one else no matter how sincere. This applys perfectely with this antenna . I know ,it seems to run against any well known laws but is not. Is just a new application of the well known laws. 73's Steve IK5IIR Reply to a comment by : WA9KKN on 2004-02-02 Its A real shame hams that are your critic are so closed minded, and you are an Engineer and they still dont believe ya. Arm chair quarter backs who are the experts in football arent they hihi. They should try something for themselves then they can be critics hihi other wise by the laws of logic which no one uses any more it seems that one should try something and judge for themselves and that is logical. I wanted to tell ya I was a critic when my Brother a fellow ham told me about your eh , well I built the simple one , stuck it up on a 7 foot bamboo pole beside my car a year and half ago and I worked every station I could hear wid gud to excellent rst reports including a Russian station that gave me a 58 report. I have been on for 40 years since 14 and I have been a electronic tech for 35 years experimented my whole life always will hihi. I use a 11 inch tall mobile antenna of my own design its not an eh-antenna but I work dx on a regular basis with great reports. I am on 20 meters all the time a bit on 18 and 15 listen for me with my 300 watts and 11 inches hihi. Have fun one and all and question everything including those that question. One must prove for oneself not the word of any one else no matter how sincere. | ||
| KC0KBH | 2004-08-11 | |
|---|---|---|
| RE: Small EH Antenna | ||
| I just talked to W0KPH the other day on psk, he was using an EH antenna he built, and he was colming in better than the people who had 4 or 5 element yagi's pointed my way. Reply to a comment by : IK5IIR on 2004-02-02 Hi, yes.... I decided to highlight here your last sentence: One must prove for oneself not the word of any one else no matter how sincere. This applys perfectely with this antenna . I know ,it seems to run against any well known laws but is not. Is just a new application of the well known laws. 73's Steve IK5IIR Reply to a comment by : WA9KKN on 2004-02-02 Its A real shame hams that are your critic are so closed minded, and you are an Engineer and they still dont believe ya. Arm chair quarter backs who are the experts in football arent they hihi. They should try something for themselves then they can be critics hihi other wise by the laws of logic which no one uses any more it seems that one should try something and judge for themselves and that is logical. I wanted to tell ya I was a critic when my Brother a fellow ham told me about your eh , well I built the simple one , stuck it up on a 7 foot bamboo pole beside my car a year and half ago and I worked every station I could hear wid gud to excellent rst reports including a Russian station that gave me a 58 report. I have been on for 40 years since 14 and I have been a electronic tech for 35 years experimented my whole life always will hihi. I use a 11 inch tall mobile antenna of my own design its not an eh-antenna but I work dx on a regular basis with great reports. I am on 20 meters all the time a bit on 18 and 15 listen for me with my 300 watts and 11 inches hihi. Have fun one and all and question everything including those that question. One must prove for oneself not the word of any one else no matter how sincere. | ||
| IK5IIR | 2004-02-02 | |
|---|---|---|
| RE: Small EH Antenna | ||
| Hi, yes.... I decided to highlight here your last sentence: One must prove for oneself not the word of any one else no matter how sincere. This applys perfectely with this antenna . I know ,it seems to run against any well known laws but is not. Is just a new application of the well known laws. 73's Steve IK5IIR Reply to a comment by : WA9KKN on 2004-02-02 Its A real shame hams that are your critic are so closed minded, and you are an Engineer and they still dont believe ya. Arm chair quarter backs who are the experts in football arent they hihi. They should try something for themselves then they can be critics hihi other wise by the laws of logic which no one uses any more it seems that one should try something and judge for themselves and that is logical. I wanted to tell ya I was a critic when my Brother a fellow ham told me about your eh , well I built the simple one , stuck it up on a 7 foot bamboo pole beside my car a year and half ago and I worked every station I could hear wid gud to excellent rst reports including a Russian station that gave me a 58 report. I have been on for 40 years since 14 and I have been a electronic tech for 35 years experimented my whole life always will hihi. I use a 11 inch tall mobile antenna of my own design its not an eh-antenna but I work dx on a regular basis with great reports. I am on 20 meters all the time a bit on 18 and 15 listen for me with my 300 watts and 11 inches hihi. Have fun one and all and question everything including those that question. One must prove for oneself not the word of any one else no matter how sincere. | ||
| WA9KKN | 2004-02-02 | |
|---|---|---|
| Small EH Antenna | ||
| Its A real shame hams that are your critic are so closed minded, and you are an Engineer and they still dont believe ya. Arm chair quarter backs who are the experts in football arent they hihi. They should try something for themselves then they can be critics hihi other wise by the laws of logic which no one uses any more it seems that one should try something and judge for themselves and that is logical. I wanted to tell ya I was a critic when my Brother a fellow ham told me about your eh , well I built the simple one , stuck it up on a 7 foot bamboo pole beside my car a year and half ago and I worked every station I could hear wid gud to excellent rst reports including a Russian station that gave me a 58 report. I have been on for 40 years since 14 and I have been a electronic tech for 35 years experimented my whole life always will hihi. I use a 11 inch tall mobile antenna of my own design its not an eh-antenna but I work dx on a regular basis with great reports. I am on 20 meters all the time a bit on 18 and 15 listen for me with my 300 watts and 11 inches hihi. Have fun one and all and question everything including those that question. One must prove for oneself not the word of any one else no matter how sincere. | ||
| IK5IIR | 2003-07-25 | |
|---|---|---|
| RE: Small EH Antenna | ||
| Hello , I am very happy to help you about. Is very simple, please go to: www.eh-antenna.com web site and look for the last revision of the antenna. This is called STAR version. Please jump over the last version , is the ultimate one. go to the amateur section of the site , then go to : http://www.eh-antenna.com/EH_Antenna_Tools_and_Tips.htm follow the demonstrations 1, 2, 3 docs. to get all the info I suggest you to read the web site and visit the EH antenna yahoo forum. In the web you will find the address. once again please skip all the old versions and start with the STAR one. I am here, if in trouble let me know. Dear friend the EH antenna is amazing, you have all the informations for free in the perfect ham spirit best 73's Stefano IK5IIR Reply to a comment by : KG6QVD on 2003-07-25 W4MQC Can you email me how to build this EH Antenna? Thanks, KG6QVD Reply to a comment by : W4MQC on 2002-09-02 The EH antenna does work. Not as good as a resonant antenna, but it does work. I built one for 20 meters in about an hour. Nice little project. Bought everything I needed for the job at Ace Hardware. It is only 18 inches long and so far have worked a ton of stations including PY, EI and UA3 as well as lots of W6's...all with respectable reports. It hangs from a tree limb about 18 feet up and looks like a bird feeder. You can talk all day long about laws of physics and why it doesn't work, but talk is pretty cheap. Build one then talk about it. Until you do that, your position on the matter is a bit weak. I am not going to replace any dipoles with my EH antenna, but it does have merit for either stealth situations or for emergency purposes. Keep the beam, leave the dipoles up...but build an EH antenna and astound your friends...and yourself. de W4MQC | ||
| KG6QVD | 2003-07-25 | |
|---|---|---|
| RE: Small EH Antenna | ||
| W4MQC Can you email me how to build this EH Antenna? Thanks, KG6QVD Reply to a comment by : W4MQC on 2002-09-02 The EH antenna does work. Not as good as a resonant antenna, but it does work. I built one for 20 meters in about an hour. Nice little project. Bought everything I needed for the job at Ace Hardware. It is only 18 inches long and so far have worked a ton of stations including PY, EI and UA3 as well as lots of W6's...all with respectable reports. It hangs from a tree limb about 18 feet up and looks like a bird feeder. You can talk all day long about laws of physics and why it doesn't work, but talk is pretty cheap. Build one then talk about it. Until you do that, your position on the matter is a bit weak. I am not going to replace any dipoles with my EH antenna, but it does have merit for either stealth situations or for emergency purposes. Keep the beam, leave the dipoles up...but build an EH antenna and astound your friends...and yourself. de W4MQC | ||
| KG6QVD | 2003-07-25 | |
|---|---|---|
| RE: Small EH Antenna | ||
| I want to build an EH Antenna. Where can I find a link that tells me exactly how to buid this? Thanks, KG6QVD - Etienne Reply to a comment by : KD3V on 2002-08-20 !!! LISTEN UP SKEPTICS !!! Please stop making fools of yourselves! If you haven't tried it you have NO BASIS for saying anything! We made one! I used it! it works! I am an electrical engineer. I have been one since 1982. These EH antennas in fact: 1. ... are not "getting something for nothing", 2. they are not "changing the laws of physics in order to make something better than it is", 3. they agree completely with the law of physics that tells us how to get radiation, and for those that have taken the time to read the relevant website, this is called the "Poynting Theorem". This antenna is simple a DIFFERENT method to work this "law of physics". 4. They WORK! I know because I used one! I sent the article to a friend who wanted to make one, he had a friend of his duplicate the 20 meter version that was detailed on the web site. He used it and then I put it up in place on the roof. Simply put, I worked the world on it! I live in Hollywood Calif. From John in South Africa, a 5-7 ... on the LONG path... a FM5 in Martinique, VK's ZL's ZK1, you name it and I only had it for 3 days! So! Read the web sites! These antennas are not using feedline rariation, they are genuine rariators using a different method to create the crossed EM field and as a result they do not need the "linear" distance used by a diplole! These antennas just do it DIFFERENTLY! Yea, i get upset by the "ignorant" who speak up with no basis from which to do so. In the place of facts you put baseless opinion, and in the place of knowledge you put "authority". You are all only making fools of yourselves and those of us who take the time to "find out for ourselves" are the ones who gain real knowledge! We were curious so we built one and we found that it works! Simple. We didn't know until we tried... but we also didn't try to slam it until we KNEW something about which we wanted to speak! I would have posted a few photos but you can already see them when you go read the web site referenced! Ours looked just like theirs do. We used copper plate wrapped around PVC cylinder. Total length.. just like on the website! http://www.qsl.net/w0kph/ This is the link that describes the "full network" verion that our friend built. http://www.qsl.net/w0kph/fullnet.html | ||
| IK5IIR | 2002-10-30 | |
|---|---|---|
| RE: Small EH Antenna | ||
| Hello my friend, thanks for your impressions. You didn't specify what kind of network ,if any, your antenna is using. Once again I have to highlight that the "EH" concept coming NOT from the physical shape of the antenna used, BUT only when the two fields E and H are properly aligned at the antenna. To achieve this target the phasing/matching network is fundamental. Hence: the simple version with a link +coil is just a fat short dipole with a sort of traditional LC resonance. this version can be 6 db down to a dipole. the only EH performing as we claim , is the full network version. This version, my friend, has a large bandwidth , no narrow, (on 20 meters about 1 MHZ at 2:1 SWR 2 MHZ at -3db)excellent efficiency , low noise on RX and so on... But, again, the antenna IF the network is not properly tuned , is just a normal fat short dipole , with HIGH Q and low efficiency. This is the key point. The antenna can have several different shape, longer ,shorter, larger....but is the network allowing it to work as claimed. Anyway you are right when you say a field strenght meter must be used during the tuning procedure. In fact there are many points where the SWR is good but only one produce the right efficiency. If you want add some more data to your antenna I will be happy to comment. 73's steve IK5IIR Reply to a comment by : K7SWL on 2002-10-30 Good Luck to all who try this antenna. I have and had good results on 20M. I do not, however believe the explanation for its successes. It looks most like the "Short Fat Dipole" from the late '40s described in many articles from that era employing many varied matching networks and having about the same results. The key factors seem to be the critical center freq. vs. the Q of the design. If the Q is high, giving a very narrow bandwidth, the energy closely matches a dipole, only about 1 to 2 db down. If it is only slightly of center freq. it is 28 to 35 db down, the same as a window screen or ladder or many other objects that will radiate "ok" in some conditions. If the size is a big requirement for your QTH, then try this design. For best results, however, pick an operating freq. and adjust using an absorption wave meter. This way you will be adjusting for max field emission, not swr etc. My antenna analyzer found MANY match points, but only one produced any output. Good luck to all with the patience to try until you get it working. I will be working on variations of this "short fat dipole" for some time. Reply to a comment by : N0TONE on 2002-08-22 The website mentioned early on was by an Italian ham who built an EH for 160 meters. He gave "results" with QSOs listed that seemed favorable. But, he obviously knew that did not provide particularly useful data - one need to compare with a "known" antenna. So he built a 160 meter vertical to compare it to. His 160 meter vertical was severely compromised, being all of 30 feet high, with only four too-short ground-mounted radials. A configuration which normally provides an antenna of maybe 5-10% efficiency. He then made lots of QSOs on both the EH and the poor vertical. In all cases, the vertical outperformed the EH by about 5-10dB. In his case, he either did not build the EH properly, or he demonstrated that EH performance is not superior. He remains open to either conclusion. There are some global points to be considered here: 1) Who cares if EH is operating with new theory? What we REALLY want to know is if this small antenna can do better than other small antenna designs. 2) Therefore, to satify #1, we need to see some genuine field strength tests made on EH antennas versus other small antennas, which are designed correctly. According to the Italian website referenced above, the 160 meter EH seems to be operating at about 0.5% efficiency. I have a 12 foot long mobile 160 meter antenna that does better than that! 3) NONE of the websites describing the EH antenna gives adequate information for measuring its performance. They make claims about the antenna's impedance, but do not tell you how to go about making those impedance measurements. I asked Ted Hart once how to make those impedance measurements and he said "measure the input impedance, then use math to calculate what the impedance is on the other side of the phasing network." But - he says the phasing network cannot be treated as a matching network, it requires new math. So, no go. I have built many small antennas over the years. By keeping the conductors big and fat where currents are high, and by using only low-loss dielectrics where the voltages are high, a small antenna can be made efficient. It won't be broadband, and it won't be 50 ohms. So the key with small antennas is not only proper construction, but then using good parts to effect the Z-match. Inductors in your matching network need to have large surface areas. #8 gauge or larger wire, or better yet, 1/4" copper tubing wound into inductors can be low loss. You have to trade off available space with desired Q. Capacitors are sometimes harder. There are no good low-loss dielectrics conveniently available. Coaxial cable makes a lossy capacitor. Window glass makes a poor dielectric. PVC and similar home construction materials have high losses when used as a capacitor dielectric. The best I've been able to do is make capacitors out of concentric copper pipes. I use PVC as a spacer, but try to minimize the number of those lossy spacers. I have a center-fed vertical for 80 meters, which is six feet high (that makes it fit my attic). My measurements show its efficiency to be about 25%. Most of the loss is in the matching network. That puts it 6dB down from a full-sized 80 meter vertical. Yes, I work DX on it, rather a lot of DX in fact. Bandwidth is only about 25kHz at the 2:1 points. If I drive it with 1.5kW, solid carrier, the antenna itself does not get warm at all, but the matching network does, mainly the inductor. So I know what part of my network could stand the most improvement. Use common sense. Don't worry about whether it's an EH or just a shortened center-fed vertical. Build the antenna, tune it as described, then do the "power" test. If you're on 160 or 80 meters, wait until daytime when the atmospheric absorption is so high that nobody can make a QSO. Lock your key for a few minutes, then shut down. Go feel the antenna to see what's warm, and work on reducing loss in that area. For 40 meters, about the only thing you can do like this is wait until nighttime when all the SW BC rolls in, and park your carrier zero-beat with a SW station, and do this same test. For 20, 15, and 10, there are lots of times when the band's dead. To the guy who said "In the meantime, the inventors of the E H antenna, Maurice C. Hately & Fathi M. Kabbary, or their employer (U.S. Patent No. 5,155,495), sure thought enough of this invention to spend some bucks on a patent attorney and filing fees. ", well, don't get too worked up. Filing patents is easy - there are books you can get that show you how to self-patent. Under $100 is the most you need to pay, unless you happen to like paying greedy corporate attorneys, or patent searchers. Yes, I'm such a person - willing to take big bucks to do things you can do yourself! Have fun guys, building antennas has more challenge and thrill than any other part of the technical side of the hobby. AM Reply to a comment by : N2KPE on 2002-08-21 WO5I: I would very much like to be kept posted on your results. Do you have any idea which band you will try/ I would especially be interested in 40. Tnx and 73. Reply to a comment by : WO5I on 2002-08-20 Folks, I am not a physicist or even an electrical engineer. But I am open-minded enough to NOT go disparaging the EH theory or design until I've tried it myself. I've seen several articles and web sites publishing results of experiments. Many of those results are favorable. For me to poo-poo it would be tantamount to me calling those hams, who I know nothing good or bad about, liars. Consider: Until Copernicus, the world thought the Earth was the center of the entire universe, and to openly state otherwise was a severe blaspheme, Until Columbus, the earth was thought to be flat (good for propagation, BAD for sailing!), Until Yager, the sound barrier was just that-- a barrier. Until Armstrong, et al, few really thought that there'd ever be a man on the moon (and probably some of the naysayers still think that all took place on a Hollywood soundstage). My challenge to the ham community that would write this idea off is this: build one yourself, per the directions on any of the published websites. They aren't expensive, they don't take any serious skill or expensive tools. The require a little patience to tune and fine-tune, but once it resonates, you can try it out head-to-head with any antenna you would otherwise use. I intend to put my money where my mouth is and build one. I might find I've wasted my time, then I will take my "I-told-you-so's" like a man. But then again, there are those that think of ham radio in general as one big waste of time! After all, isn't ham radio chock-full of people that experiment? Maybe the EH is a better mousetrap. | ||
| K7SWL | 2002-10-30 | |
|---|---|---|
| RE: Small EH Antenna | ||
| Good Luck to all who try this antenna. I have and had good results on 20M. I do not, however believe the explanation for its successes. It looks most like the "Short Fat Dipole" from the late '40s described in many articles from that era employing many varied matching networks and having about the same results. The key factors seem to be the critical center freq. vs. the Q of the design. If the Q is high, giving a very narrow bandwidth, the energy closely matches a dipole, only about 1 to 2 db down. If it is only slightly of center freq. it is 28 to 35 db down, the same as a window screen or ladder or many other objects that will radiate "ok" in some conditions. If the size is a big requirement for your QTH, then try this design. For best results, however, pick an operating freq. and adjust using an absorption wave meter. This way you will be adjusting for max field emission, not swr etc. My antenna analyzer found MANY match points, but only one produced any output. Good luck to all with the patience to try until you get it working. I will be working on variations of this "short fat dipole" for some time. Reply to a comment by : N0TONE on 2002-08-22 The website mentioned early on was by an Italian ham who built an EH for 160 meters. He gave "results" with QSOs listed that seemed favorable. But, he obviously knew that did not provide particularly useful data - one need to compare with a "known" antenna. So he built a 160 meter vertical to compare it to. His 160 meter vertical was severely compromised, being all of 30 feet high, with only four too-short ground-mounted radials. A configuration which normally provides an antenna of maybe 5-10% efficiency. He then made lots of QSOs on both the EH and the poor vertical. In all cases, the vertical outperformed the EH by about 5-10dB. In his case, he either did not build the EH properly, or he demonstrated that EH performance is not superior. He remains open to either conclusion. There are some global points to be considered here: 1) Who cares if EH is operating with new theory? What we REALLY want to know is if this small antenna can do better than other small antenna designs. 2) Therefore, to satify #1, we need to see some genuine field strength tests made on EH antennas versus other small antennas, which are designed correctly. According to the Italian website referenced above, the 160 meter EH seems to be operating at about 0.5% efficiency. I have a 12 foot long mobile 160 meter antenna that does better than that! 3) NONE of the websites describing the EH antenna gives adequate information for measuring its performance. They make claims about the antenna's impedance, but do not tell you how to go about making those impedance measurements. I asked Ted Hart once how to make those impedance measurements and he said "measure the input impedance, then use math to calculate what the impedance is on the other side of the phasing network." But - he says the phasing network cannot be treated as a matching network, it requires new math. So, no go. I have built many small antennas over the years. By keeping the conductors big and fat where currents are high, and by using only low-loss dielectrics where the voltages are high, a small antenna can be made efficient. It won't be broadband, and it won't be 50 ohms. So the key with small antennas is not only proper construction, but then using good parts to effect the Z-match. Inductors in your matching network need to have large surface areas. #8 gauge or larger wire, or better yet, 1/4" copper tubing wound into inductors can be low loss. You have to trade off available space with desired Q. Capacitors are sometimes harder. There are no good low-loss dielectrics conveniently available. Coaxial cable makes a lossy capacitor. Window glass makes a poor dielectric. PVC and similar home construction materials have high losses when used as a capacitor dielectric. The best I've been able to do is make capacitors out of concentric copper pipes. I use PVC as a spacer, but try to minimize the number of those lossy spacers. I have a center-fed vertical for 80 meters, which is six feet high (that makes it fit my attic). My measurements show its efficiency to be about 25%. Most of the loss is in the matching network. That puts it 6dB down from a full-sized 80 meter vertical. Yes, I work DX on it, rather a lot of DX in fact. Bandwidth is only about 25kHz at the 2:1 points. If I drive it with 1.5kW, solid carrier, the antenna itself does not get warm at all, but the matching network does, mainly the inductor. So I know what part of my network could stand the most improvement. Use common sense. Don't worry about whether it's an EH or just a shortened center-fed vertical. Build the antenna, tune it as described, then do the "power" test. If you're on 160 or 80 meters, wait until daytime when the atmospheric absorption is so high that nobody can make a QSO. Lock your key for a few minutes, then shut down. Go feel the antenna to see what's warm, and work on reducing loss in that area. For 40 meters, about the only thing you can do like this is wait until nighttime when all the SW BC rolls in, and park your carrier zero-beat with a SW station, and do this same test. For 20, 15, and 10, there are lots of times when the band's dead. To the guy who said "In the meantime, the inventors of the E H antenna, Maurice C. Hately & Fathi M. Kabbary, or their employer (U.S. Patent No. 5,155,495), sure thought enough of this invention to spend some bucks on a patent attorney and filing fees. ", well, don't get too worked up. Filing patents is easy - there are books you can get that show you how to self-patent. Under $100 is the most you need to pay, unless you happen to like paying greedy corporate attorneys, or patent searchers. Yes, I'm such a person - willing to take big bucks to do things you can do yourself! Have fun guys, building antennas has more challenge and thrill than any other part of the technical side of the hobby. AM Reply to a comment by : N2KPE on 2002-08-21 WO5I: I would very much like to be kept posted on your results. Do you have any idea which band you will try/ I would especially be interested in 40. Tnx and 73. Reply to a comment by : WO5I on 2002-08-20 Folks, I am not a physicist or even an electrical engineer. But I am open-minded enough to NOT go disparaging the EH theory or design until I've tried it myself. I've seen several articles and web sites publishing results of experiments. Many of those results are favorable. For me to poo-poo it would be tantamount to me calling those hams, who I know nothing good or bad about, liars. Consider: Until Copernicus, the world thought the Earth was the center of the entire universe, and to openly state otherwise was a severe blaspheme, Until Columbus, the earth was thought to be flat (good for propagation, BAD for sailing!), Until Yager, the sound barrier was just that-- a barrier. Until Armstrong, et al, few really thought that there'd ever be a man on the moon (and probably some of the naysayers still think that all took place on a Hollywood soundstage). My challenge to the ham community that would write this idea off is this: build one yourself, per the directions on any of the published websites. They aren't expensive, they don't take any serious skill or expensive tools. The require a little patience to tune and fine-tune, but once it resonates, you can try it out head-to-head with any antenna you would otherwise use. I intend to put my money where my mouth is and build one. I might find I've wasted my time, then I will take my "I-told-you-so's" like a man. But then again, there are those that think of ham radio in general as one big waste of time! After all, isn't ham radio chock-full of people that experiment? Maybe the EH is a better mousetrap. | ||
| G4KSG | 2002-09-23 | |
|---|---|---|
| Small EH Antenna | ||
| Hi guys. Just to let you know I have recently bought and received a 20m EH from Steve at Arno Elettronica and have been doing some tests against a 20m loop (in trees), a dipole (in the roof of my house) and my mobile whip on the car (next to my house). The 3 existing antennas give very similar results (as you would expect considering their compromise circumstances) and the EH is deaf in comparison despite having 1:1 and good bandwith. Have I got an ATU in the air? HOWEVER on some occasions the EH is equal to the best of the others!!! But not often enough to want me to keep as my main 20m antenna. This suggests the EH is not a sham. Is it all a matter of the angle of the incoming signal? polarisation? vertical beamwidth? I appreciate the wise words from the boffins on this thread and all the talk of dbs blah blah blah but the bottom line is does it work as well as anything else the 'very' average operator could/would put up. By this I mean would you chose a 4 ele at 100' or 1m V beam at whatever if you could do either. The EH, assuming its all true, isn't meant to compete with those but it should with the antennas I've set up/used. Steve knows about this and suggests there is some interaction so I have promised to go to a clear space and compare the EH with the whip and let him know the results. Watch this space. I must say the physical construction is good value for money (despite the loose SO239). Hey I believe in aliens I just haven't seen one yet so I'm open minded about the EH - I really do hope it works. What I've seen so far (EH wise that is) is not credible. | ||
| AC6IJ | 2002-09-22 | |
|---|---|---|
| RE: Small EH Antenna | ||
| Hi again, after making three of these antennas including the 20 meter full network design I can say I have made many contacts with them and had a lot of fun making the antenna and using it with my outdoor laptop computer. It takes the place of an unhandy carry all type of antenna and being only three feet tall, I can take it anywhere. You cant string up a dipole antenna in a place where there are no trees but this EH antenna can be used anywhere. Bottom line is don't some of you hams like to have fun any more or just show your education on complaints? Bill AC6IJ Reply to a comment by : N0GV on 2002-09-12 Bob, That is the point -- IF it does then what you have is a short, fat, dipole and this is not a new creation but a well known and understood antenna. The "Super C" from Gap is a much closer analog to the CFA than this thing is. Remember, just because a Patent has been issued there is no assurance that something will work as advertised or even that the Science is valid..... Grover Larkins Reply to a comment by : W7KWS on 2002-09-12 I was under the impression that the phasing network in the EH antenna produced this needed phase shift, but I admit, I'm not an expert in this area and will leave it to those who know for sure. I can't wait to see the outcome of this debate!!! I do note that the patent states that two separate fields are produced with the result being what I thought was purported to happen in the EH antenna, just through separate means of feeding the entergy into the radiating elements. 73, Bob Reply to a comment by : N0TONE on 2002-09-12 W7KWS, thanks for the patent info. I was aware of the CFA patent, but the EH does not fit that category. The CFA patent is very clear that the transmitter power is split into two separate signal, which have independently adjustable amplitude and phase. There are seperate elements for creating the E and H fields. Therefore, the drive network has two output ports - four wires. The EH antenna, however, does not include this critical item (the patent is clear on this - if you do not split the drive, the patent does not cover the antenna). In the EH antenna, only one port (two wires) excite the antenna, thus preventing separate control of amplitude and phase for the separate elements creating E and H. In fact, in the EH antenna, there are no such separate elements. AM Reply to a comment by : W7KWS on 2002-09-11 The U.S. Patent No. 5,155,495 seems to cover this antenna. If not right on target, it sure seems close. You can download the text and images at the U.S. Patent and Trademark site. The URL is: http://patft.uspto.gov/netahtml/srchnum.htm 73, Bob Reply to a comment by : IK5IIR on 2002-09-11 To Dr. Grover here we go....the ego of the "doctor" was hit. I am sorry but many of your sentences are wrong 1) the EH antenna can not be modeled with program that don't consider the current displacement. those program doesn't work with EH. 2) Poynting says S= EXH that symbol X means that the fields are orthogonal in SPACE (90 degrees apart) and in TIME phase. BOTH OF THEM. 3) The eh antenna ,like a vertical dipole, has the H field and the E field 90 degrees apart in space .The displacement current produce the H field. Then the matching /phasing network is responsible for the time alignement 4 I never said the impedance is resisitive...wrong! I told you the RR is 2360 ohm. the impedance of a typical eh is 2360 -J4000 5) the phase of the voltage in the cylinders is +90 and -90 or 180 degrees apart. BUT the network doesn't produce any phase shift of the voltage from the input and the output. only current delay. (phase shift) 6) I have no doubt you didn't find anything on the network. there must be a special phase shift condition. I have no idea what you built. as many experimenters say, the antenna works, if your didn't you had not an eh antenna. 7) there are not so many antennas around. i got many times S 9+ using only 80 watts from USA. I repeat i made long comparisons against verticals (full size)and I never get differences. I described to you a lot of features. You didn't comment. probabily you have not read them... is the same story...is not on the books hence it can not work. everybody is free to believe what he wants. bythe way..the supe C antenna is NOT a cfa antenna ! is just a traditional resonant antenna with a small L and a big C to achieve the resonance. the eh antenna is much smaller , but it works with a phase to align the fields..is completely different. Sincerly, steve Ik5IIR Reply to a comment by : N0GV on 2002-09-11 Oh, yes, I forgot. The guys at GAP have a neat antenna which will actually work. It is a crossed field antenna, the "Super C." Note that the current is carried in the short rod between the screen plate and "can" and that the E-Field is virtually vertical with the H field cylindrically symmetric in the phi direction -- hence E X H is at about 90 degrees..... No smoke, no mirrors, just good ol Uncle Max hard at work! Grover Reply to a comment by : N0GV on 2002-09-11 KE0VH please can the personal attacks! I've no ego to boost here -- this guy has spouted bull and folks are swallowing it. If you are an RF engineer please look at what is claimed and then look at what you can document. 1) I've made "similar" structures and put them on a network analyzer and they just won't fly. 2) I've modelled these things using FDTD and MOM based simulation programs for RF and the NEC based (MOM - type) software tools and they confirmed the results from (1) above. 3) I've yet to hear ANY DX from anyone using one of these and I'm on the air on 20m about 1-2 hours per night. Signals from Italy are booming in here at 10-20 dB over S-9 on a dipole from 3 element Yagis -- this antenna should, if it worked as claimed, be at S-9 or so. Funny, I can hear an S-5 from India and an S-3 from the Pacific, whay can't I find even ONE person using one of these on the band? 4) 2300 Ohms feedpoint impedance REAL part with zero ohms reactive is claimed (resistive)! How is that related to radiation resistance? It is not necessarily related at all -- all it indicates is a very high Q factor in the feed network! What we can say from that is that the BW is likely quite small! 5) Depending on SPATIAL orientation of the conductors we get a SPATIAL phasing of E and H as well as the time domain phasing described by the author. Poynting's theorem dictates that the SPATIAL phase relationship between the E and H fields dictates propagation not just the TIME phasing. What this guy is claiming is that by driving the two sides 180 degrees apart in phase he is transmitting power out -- this is specious as the feedline is already 180 degrees shifted making his radiators IN PHASE and virtually colocated -- hence cancellation of the Electromagnetic wave is indicated. 6) If you want to call this a short fat dipole go right ahead, that model is correct for the critter. Where the BIG spatial problem arises is in the H or B field which, on a long dipole, is modelled as being cylindrical in shape with the E-field orthogonal to it. If you look at a very short wire (or a short Fat wire) the H field is not truly cylindrical at the ends but is dipole-like in form yet the E field is still Z axis directed along the length of the wire making the SPATIAL angle between the E and H field in the all-critical High E-field gap less than 90 degrees thus reducing propagation efficiency dramaticly. In short, this is a non-starter! Sorry, Grover Larkins Reply to a comment by : KE0VH on 2002-09-11 Dr. Grover, If you don't like the idea, you certainly don't have to use it. Have you even built one and tried it? Again, the long and short of it is IT WORKS. Maybe not as well as the monoband vertical or beam as we all know it, but it works. The proof is in the QSO's made. Some of us have neither the money, space or time to have the antenna's and setups AND the time to be so critical of the experimental spirit. Chill out.... The idea here is to SHARE AN IDEA THAT MIGHT BE HELPFUL. Not boost our own ego's. KE0VH Also an RF engineer for many years. Again, The proof is in the QSO's made. | ||
| N0GV | 2002-09-12 | |
|---|---|---|
| RE: Small EH Antenna | ||
| Bob, That is the point -- IF it does then what you have is a short, fat, dipole and this is not a new creation but a well known and understood antenna. The "Super C" from Gap is a much closer analog to the CFA than this thing is. Remember, just because a Patent has been issued there is no assurance that something will work as advertised or even that the Science is valid..... Grover Larkins Reply to a comment by : W7KWS on 2002-09-12 I was under the impression that the phasing network in the EH antenna produced this needed phase shift, but I admit, I'm not an expert in this area and will leave it to those who know for sure. I can't wait to see the outcome of this debate!!! I do note that the patent states that two separate fields are produced with the result being what I thought was purported to happen in the EH antenna, just through separate means of feeding the entergy into the radiating elements. 73, Bob Reply to a comment by : N0TONE on 2002-09-12 W7KWS, thanks for the patent info. I was aware of the CFA patent, but the EH does not fit that category. The CFA patent is very clear that the transmitter power is split into two separate signal, which have independently adjustable amplitude and phase. There are seperate elements for creating the E and H fields. Therefore, the drive network has two output ports - four wires. The EH antenna, however, does not include this critical item (the patent is clear on this - if you do not split the drive, the patent does not cover the antenna). In the EH antenna, only one port (two wires) excite the antenna, thus preventing separate control of amplitude and phase for the separate elements creating E and H. In fact, in the EH antenna, there are no such separate elements. AM Reply to a comment by : W7KWS on 2002-09-11 The U.S. Patent No. 5,155,495 seems to cover this antenna. If not right on target, it sure seems close. You can download the text and images at the U.S. Patent and Trademark site. The URL is: http://patft.uspto.gov/netahtml/srchnum.htm 73, Bob Reply to a comment by : IK5IIR on 2002-09-11 To Dr. Grover here we go....the ego of the "doctor" was hit. I am sorry but many of your sentences are wrong 1) the EH antenna can not be modeled with program that don't consider the current displacement. those program doesn't work with EH. 2) Poynting says S= EXH that symbol X means that the fields are orthogonal in SPACE (90 degrees apart) and in TIME phase. BOTH OF THEM. 3) The eh antenna ,like a vertical dipole, has the H field and the E field 90 degrees apart in space .The displacement current produce the H field. Then the matching /phasing network is responsible for the time alignement 4 I never said the impedance is resisitive...wrong! I told you the RR is 2360 ohm. the impedance of a typical eh is 2360 -J4000 5) the phase of the voltage in the cylinders is +90 and -90 or 180 degrees apart. BUT the network doesn't produce any phase shift of the voltage from the input and the output. only current delay. (phase shift) 6) I have no doubt you didn't find anything on the network. there must be a special phase shift condition. I have no idea what you built. as many experimenters say, the antenna works, if your didn't you had not an eh antenna. 7) there are not so many antennas around. i got many times S 9+ using only 80 watts from USA. I repeat i made long comparisons against verticals (full size)and I never get differences. I described to you a lot of features. You didn't comment. probabily you have not read them... is the same story...is not on the books hence it can not work. everybody is free to believe what he wants. bythe way..the supe C antenna is NOT a cfa antenna ! is just a traditional resonant antenna with a small L and a big C to achieve the resonance. the eh antenna is much smaller , but it works with a phase to align the fields..is completely different. Sincerly, steve Ik5IIR Reply to a comment by : N0GV on 2002-09-11 Oh, yes, I forgot. The guys at GAP have a neat antenna which will actually work. It is a crossed field antenna, the "Super C." Note that the current is carried in the short rod between the screen plate and "can" and that the E-Field is virtually vertical with the H field cylindrically symmetric in the phi direction -- hence E X H is at about 90 degrees..... No smoke, no mirrors, just good ol Uncle Max hard at work! Grover Reply to a comment by : N0GV on 2002-09-11 KE0VH please can the personal attacks! I've no ego to boost here -- this guy has spouted bull and folks are swallowing it. If you are an RF engineer please look at what is claimed and then look at what you can document. 1) I've made "similar" structures and put them on a network analyzer and they just won't fly. 2) I've modelled these things using FDTD and MOM based simulation programs for RF and the NEC based (MOM - type) software tools and they confirmed the results from (1) above. 3) I've yet to hear ANY DX from anyone using one of these and I'm on the air on 20m about 1-2 hours per night. Signals from Italy are booming in here at 10-20 dB over S-9 on a dipole from 3 element Yagis -- this antenna should, if it worked as claimed, be at S-9 or so. Funny, I can hear an S-5 from India and an S-3 from the Pacific, whay can't I find even ONE person using one of these on the band? 4) 2300 Ohms feedpoint impedance REAL part with zero ohms reactive is claimed (resistive)! How is that related to radiation resistance? It is not necessarily related at all -- all it indicates is a very high Q factor in the feed network! What we can say from that is that the BW is likely quite small! 5) Depending on SPATIAL orientation of the conductors we get a SPATIAL phasing of E and H as well as the time domain phasing described by the author. Poynting's theorem dictates that the SPATIAL phase relationship between the E and H fields dictates propagation not just the TIME phasing. What this guy is claiming is that by driving the two sides 180 degrees apart in phase he is transmitting power out -- this is specious as the feedline is already 180 degrees shifted making his radiators IN PHASE and virtually colocated -- hence cancellation of the Electromagnetic wave is indicated. 6) If you want to call this a short fat dipole go right ahead, that model is correct for the critter. Where the BIG spatial problem arises is in the H or B field which, on a long dipole, is modelled as being cylindrical in shape with the E-field orthogonal to it. If you look at a very short wire (or a short Fat wire) the H field is not truly cylindrical at the ends but is dipole-like in form yet the E field is still Z axis directed along the length of the wire making the SPATIAL angle between the E and H field in the all-critical High E-field gap less than 90 degrees thus reducing propagation efficiency dramaticly. In short, this is a non-starter! Sorry, Grover Larkins Reply to a comment by : KE0VH on 2002-09-11 Dr. Grover, If you don't like the idea, you certainly don't have to use it. Have you even built one and tried it? Again, the long and short of it is IT WORKS. Maybe not as well as the monoband vertical or beam as we all know it, but it works. The proof is in the QSO's made. Some of us have neither the money, space or time to have the antenna's and setups AND the time to be so critical of the experimental spirit. Chill out.... The idea here is to SHARE AN IDEA THAT MIGHT BE HELPFUL. Not boost our own ego's. KE0VH Also an RF engineer for many years. Again, The proof is in the QSO's made. | ||
| W7KWS | 2002-09-12 | |
|---|---|---|
| RE: Small EH Antenna | ||
| I was under the impression that the phasing network in the EH antenna produced this needed phase shift, but I admit, I'm not an expert in this area and will leave it to those who know for sure. I can't wait to see the outcome of this debate!!! I do note that the patent states that two separate fields are produced with the result being what I thought was purported to happen in the EH antenna, just through separate means of feeding the entergy into the radiating elements. 73, Bob Reply to a comment by : N0TONE on 2002-09-12 W7KWS, thanks for the patent info. I was aware of the CFA patent, but the EH does not fit that category. The CFA patent is very clear that the transmitter power is split into two separate signal, which have independently adjustable amplitude and phase. There are seperate elements for creating the E and H fields. Therefore, the drive network has two output ports - four wires. The EH antenna, however, does not include this critical item (the patent is clear on this - if you do not split the drive, the patent does not cover the antenna). In the EH antenna, only one port (two wires) excite the antenna, thus preventing separate control of amplitude and phase for the separate elements creating E and H. In fact, in the EH antenna, there are no such separate elements. AM Reply to a comment by : W7KWS on 2002-09-11 The U.S. Patent No. 5,155,495 seems to cover this antenna. If not right on target, it sure seems close. You can download the text and images at the U.S. Patent and Trademark site. The URL is: http://patft.uspto.gov/netahtml/srchnum.htm 73, Bob Reply to a comment by : IK5IIR on 2002-09-11 To Dr. Grover here we go....the ego of the "doctor" was hit. I am sorry but many of your sentences are wrong 1) the EH antenna can not be modeled with program that don't consider the current displacement. those program doesn't work with EH. 2) Poynting says S= EXH that symbol X means that the fields are orthogonal in SPACE (90 degrees apart) and in TIME phase. BOTH OF THEM. 3) The eh antenna ,like a vertical dipole, has the H field and the E field 90 degrees apart in space .The displacement current produce the H field. Then the matching /phasing network is responsible for the time alignement 4 I never said the impedance is resisitive...wrong! I told you the RR is 2360 ohm. the impedance of a typical eh is 2360 -J4000 5) the phase of the voltage in the cylinders is +90 and -90 or 180 degrees apart. BUT the network doesn't produce any phase shift of the voltage from the input and the output. only current delay. (phase shift) 6) I have no doubt you didn't find anything on the network. there must be a special phase shift condition. I have no idea what you built. as many experimenters say, the antenna works, if your didn't you had not an eh antenna. 7) there are not so many antennas around. i got many times S 9+ using only 80 watts from USA. I repeat i made long comparisons against verticals (full size)and I never get differences. I described to you a lot of features. You didn't comment. probabily you have not read them... is the same story...is not on the books hence it can not work. everybody is free to believe what he wants. bythe way..the supe C antenna is NOT a cfa antenna ! is just a traditional resonant antenna with a small L and a big C to achieve the resonance. the eh antenna is much smaller , but it works with a phase to align the fields..is completely different. Sincerly, steve Ik5IIR Reply to a comment by : N0GV on 2002-09-11 Oh, yes, I forgot. The guys at GAP have a neat antenna which will actually work. It is a crossed field antenna, the "Super C." Note that the current is carried in the short rod between the screen plate and "can" and that the E-Field is virtually vertical with the H field cylindrically symmetric in the phi direction -- hence E X H is at about 90 degrees..... No smoke, no mirrors, just good ol Uncle Max hard at work! Grover Reply to a comment by : N0GV on 2002-09-11 KE0VH please can the personal attacks! I've no ego to boost here -- this guy has spouted bull and folks are swallowing it. If you are an RF engineer please look at what is claimed and then look at what you can document. 1) I've made "similar" structures and put them on a network analyzer and they just won't fly. 2) I've modelled these things using FDTD and MOM based simulation programs for RF and the NEC based (MOM - type) software tools and they confirmed the results from (1) above. 3) I've yet to hear ANY DX from anyone using one of these and I'm on the air on 20m about 1-2 hours per night. Signals from Italy are booming in here at 10-20 dB over S-9 on a dipole from 3 element Yagis -- this antenna should, if it worked as claimed, be at S-9 or so. Funny, I can hear an S-5 from India and an S-3 from the Pacific, whay can't I find even ONE person using one of these on the band? 4) 2300 Ohms feedpoint impedance REAL part with zero ohms reactive is claimed (resistive)! How is that related to radiation resistance? It is not necessarily related at all -- all it indicates is a very high Q factor in the feed network! What we can say from that is that the BW is likely quite small! 5) Depending on SPATIAL orientation of the conductors we get a SPATIAL phasing of E and H as well as the time domain phasing described by the author. Poynting's theorem dictates that the SPATIAL phase relationship between the E and H fields dictates propagation not just the TIME phasing. What this guy is claiming is that by driving the two sides 180 degrees apart in phase he is transmitting power out -- this is specious as the feedline is already 180 degrees shifted making his radiators IN PHASE and virtually colocated -- hence cancellation of the Electromagnetic wave is indicated. 6) If you want to call this a short fat dipole go right ahead, that model is correct for the critter. Where the BIG spatial problem arises is in the H or B field which, on a long dipole, is modelled as being cylindrical in shape with the E-field orthogonal to it. If you look at a very short wire (or a short Fat wire) the H field is not truly cylindrical at the ends but is dipole-like in form yet the E field is still Z axis directed along the length of the wire making the SPATIAL angle between the E and H field in the all-critical High E-field gap less than 90 degrees thus reducing propagation efficiency dramaticly. In short, this is a non-starter! Sorry, Grover Larkins Reply to a comment by : KE0VH on 2002-09-11 Dr. Grover, If you don't like the idea, you certainly don't have to use it. Have you even built one and tried it? Again, the long and short of it is IT WORKS. Maybe not as well as the monoband vertical or beam as we all know it, but it works. The proof is in the QSO's made. Some of us have neither the money, space or time to have the antenna's and setups AND the time to be so critical of the experimental spirit. Chill out.... The idea here is to SHARE AN IDEA THAT MIGHT BE HELPFUL. Not boost our own ego's. KE0VH Also an RF engineer for many years. Again, The proof is in the QSO's made. | ||
| N0GV | 2002-09-12 | |
|---|---|---|
| RE: Small EH Antenna | ||
| I've addressed EACH comment with an answer, read them, check the facts and decide for yourself if it is worth your time to play with this silly thing. >To Dr. Grover< >here we go....the ego of the "doctor" was hit. I am sorry but many of your sentences are wrong< Gee I've only found one -- the Gap super "C" is strictly not a CFA but uses geometry to emulate one really other than in the patented sense (wonder why not ;-) ). >1) the EH antenna can not be modeled with program that don't consider the current displacement. those program doesn't work with EH.< Okay and which programs are those and where does the "Displacement Current" you like to describe originate? Hmmmm... seems to me it comes from D = epsilon E but in this antenna the epsilon is that of free space so now what? Clearly you do not like the method of moments -- is the Finite Difference Time Domain method more acceptable to you? That does E-field based computations. Strange but it seems to give virtually the same results except in a few high dielectric constant interface problems on this sort of structure. >2) Poynting says S= EXH that symbol X means that the fields are orthogonal in SPACE (90 degrees apart) and in TIME phase. BOTH OF THEM.< You are repeating me but you obviously do not understand a vector cross product -- please understand that the resultant of a cross product is |E||H|sin(theta) where theta is the angle between the vectors E and H, if they are aligned with 0 or 180 degrees of spatial phase (theta) then the cross product is zero and NOTHING propagates. Time phasing relates to polarization. >3) The eh antenna ,like a vertical dipole, has the H field and the E field 90 degrees apart in space .The displacement current produce the H field. Then the matching /phasing network is responsible for the time alignement< WHAT DISPLACEMENT CURRENT. Where is the polarization charge density which it represents. This claim is bogus. You have charges moving on conductors, not on the surfaces of dielectrics! >4 I never said the impedance is resisitive...wrong! I told you the RR is 2360 ohm. the impedance of a typical eh is 2360 - J4000< Really, you said that the Radiation Resistance is 2360 Ohms? Bob Collin's book "Antennas and Radiowave Propagation" (1985) pg 92: Ra = 20(pi^2)(length/wavelength)^2 for short dipoles (what we have here unless you are claiming radiation from the matching network) gives us a radiation resistance of 0.5 Ohms for a 1m long (total length) dipole used on a 20m wavelength. OK, Where is that 2300 Ohms? Furthermore I'd be really interested in getting the specs on the equipment used to get those numbers for the feedpoint impedance, there are not many pieces of equipment commercially available to measure things that far from Z0 = 50 or 75 Ohms.... Also of interest is how you intend to reduce the 2360-j4000 to a 50 ohm feedpoint.... Sure an inductor can be made to cancel the -j4000 capacitive reactance (45 uH should do for 14.2 MHz) let's see, that is about 10 turns or so of 6mm Cu wire at about 5 cm dia., right? (don't have my tables here but that seems OK). Now about that 2360 ohms of real reactance? Want to use an L match or a transformer? Kind of difficult isn't it? >5) the phase of the voltage in the cylinders is +90 and -90 or 180 degrees apart. BUT the network doesn't produce any phase shift of the voltage from the input and the output. only current delay. (phase shift)< Really -- that is COOL -- and what are you referenceing your current phase shift to? No let me guess.... THE VOLTAGE. >6) I have no doubt you didn't find anything on the network. there must be a special phase shift condition.< Do you even know what a vector network analyzer is and what it measures? Phase angle, Magnitude and Delay are SIMULTANEOUSLY measured. >I have no idea what you built. as many experimenters say, the antenna works, if your didn't you had not an eh antenna.< The problem with circular logic is that it enables you to take a big bite out of your own backside; you have taken at least two really helpings of it here! >7) there are not so many antennas around.< I'll bet -- pop a kW in that puppy and it should be a really neat corona generator..... >i got many times S 9+ using only 80 watts from USA. I repeat i made long comparisons against verticals (full size)and I never get differences.< Wow! Here we go -- I read that a guy got a S-4 or so using a dummy load into South Dakota in a recent contest.... I've heard <5 Watt QRP stations at S-9 on a good night (not recently though :-( ) Here we are into anecdotal measurements; heck when the band is open I've made contacts into South Africa using a blown Balun and 70 Watts on 20 meters, 59 reported! >I described to you a lot of features. You didn't comment. probabily you have not read them...< Hmmm... aren't features what software developers try to call BUGS? Reason for no comment was that I wanted to give you a graceful exit.... >is the same story...is not on the books hence it can not work.< Nope -- lots of stuff "not on the books" can work but the laws of Physics cannot be violated to "make" them work. >everybody is free to believe what he wants.< Belief has very little to do with hard Science, I can Believe that this approach or that that Hypothesis is the correct one but I cannot confuse this with a proven fact or design. Let's not get into religous antenna design here... :-) >by the way..the supe C antenna is NOT a cfa antenna ! is just a traditional resonant antenna with a small L and a big C to achieve the resonance.< Not really as a great deal of the E field lies vertically between the bottom of the "can" and the top of the grid and the majority of the current is in the "mast" which runs between them hence generating the crossed fields more efficiently than in a dipole. Do a field diagram and you'll see what I mean. It really is a clever design! No smoke, no mirrors, no claiming something new from Poynting's theorem/law or any rescinding of Uncle Max's laws/equations..... >the eh antenna is much smaller , but it works with a phase to align the fields..is completely different.< Sure it is -- and it does not work as claimed! >Sincerly, steve Ik5IIR< Grover Larkins Reply to a comment by : N0TONE on 2002-09-11 Grover I was with you until you called the Super-C a CFA. Gap has never made that claim, and my modelling of it (Ansoft HFSS) shows that it can also be analyzed as a vertically-oriented end-loaded short dipole. The measurements I've done with the antenna (admittedly not perfect, because of the usual problems developing a "range" for HF measurements) seem to substantiate the modelling. You have hit upon several points which I attempted to make earlier. The claims about the "phasing" network are clearly bogus. The antenna has a drive point impedance, and the relationship between I and V are set by that impedance. No matching network (even if you call it a 'phasing network' can alter that relationship in a one-port device. Interestingly, IK5IIR's posting on how the phasing network operates is an exact description of one way that you'd make a simple impedance matching network for a complex impedance, and nothing more. But does the proposed construction article have merit? I think so. My own short fat dipole experiments used thin copper as a conductor. Even if only a few mils thick, a three to six inch diamater copper conductor (aluminum is not a lot less conductive) has a LOT of surface area and very low RF resistance as a result. It also has plenty of heat radiating surface. My short 40 meter vertical dipole (6 feet tall) does not get warm to the touch, with 1kW CW into it. I've had corona arcing at the ends, and have cured that with copper hemispheres brazed onto it. DX performance is superior to a comparison antenna which is admittedly a compromise. My full-size 40 meter vertical is ground-mounted, and even with the radials, a fair amount of the near fields have to suffer penetrating poor soil. I top-load this antenna and "make it work" on 80 meters. The results of the short fat dipole are better by a few dB (when I factor out the "wow" effect from the other end of the link), and I "blame" that on the fact that the short fat dipole sits about 15 feet in the air, making it less fussy about having a good ground underneath, than the vertical which sits on the ground. Matching for my short fat dipole is via motor-driven variable inductor and broadband transformer, installed at the antenna, inside the copper tubes. In fact, the copper tube diameter was chosen not for any perceived electromagnetic need, but because it fit the matching components. By the way, I have been completely unable to find the so-called patent on this antenna. In the QRZ.COM article, the claim was made that there was a patent on the EH that was separate from the CFA. If anybody knows what the patent number is, I'd like to see it. For the time being, I'll assume the claim was false. AM Reply to a comment by : N0GV on 2002-09-11 Oh, yes, I forgot. The guys at GAP have a neat antenna which will actually work. It is a crossed field antenna, the "Super C." Note that the current is carried in the short rod between the screen plate and "can" and that the E-Field is virtually vertical with the H field cylindrically symmetric in the phi direction -- hence E X H is at about 90 degrees..... No smoke, no mirrors, just good ol Uncle Max hard at work! Grover Reply to a comment by : N0GV on 2002-09-11 KE0VH please can the personal attacks! I've no ego to boost here -- this guy has spouted bull and folks are swallowing it. If you are an RF engineer please look at what is claimed and then look at what you can document. 1) I've made "similar" structures and put them on a network analyzer and they just won't fly. 2) I've modelled these things using FDTD and MOM based simulation programs for RF and the NEC based (MOM - type) software tools and they confirmed the results from (1) above. 3) I've yet to hear ANY DX from anyone using one of these and I'm on the air on 20m about 1-2 hours per night. Signals from Italy are booming in here at 10-20 dB over S-9 on a dipole from 3 element Yagis -- this antenna should, if it worked as claimed, be at S-9 or so. Funny, I can hear an S-5 from India and an S-3 from the Pacific, whay can't I find even ONE person using one of these on the band? 4) 2300 Ohms feedpoint impedance REAL part with zero ohms reactive is claimed (resistive)! How is that related to radiation resistance? It is not necessarily related at all -- all it indicates is a very high Q factor in the feed network! What we can say from that is that the BW is likely quite small! 5) Depending on SPATIAL orientation of the conductors we get a SPATIAL phasing of E and H as well as the time domain phasing described by the author. Poynting's theorem dictates that the SPATIAL phase relationship between the E and H fields dictates propagation not just the TIME phasing. What this guy is claiming is that by driving the two sides 180 degrees apart in phase he is transmitting power out -- this is specious as the feedline is already 180 degrees shifted making his radiators IN PHASE and virtually colocated -- hence cancellation of the Electromagnetic wave is indicated. 6) If you want to call this a short fat dipole go right ahead, that model is correct for the critter. Where the BIG spatial problem arises is in the H or B field which, on a long dipole, is modelled as being cylindrical in shape with the E-field orthogonal to it. If you look at a very short wire (or a short Fat wire) the H field is not truly cylindrical at the ends but is dipole-like in form yet the E field is still Z axis directed along the length of the wire making the SPATIAL angle between the E and H field in the all-critical High E-field gap less than 90 degrees thus reducing propagation efficiency dramaticly. In short, this is a non-starter! Sorry, Grover Larkins Reply to a comment by : KE0VH on 2002-09-11 Dr. Grover, If you don't like the idea, you certainly don't have to use it. Have you even built one and tried it? Again, the long and short of it is IT WORKS. Maybe not as well as the monoband vertical or beam as we all know it, but it works. The proof is in the QSO's made. Some of us have neither the money, space or time to have the antenna's and setups AND the time to be so critical of the experimental spirit. Chill out.... The idea here is to SHARE AN IDEA THAT MIGHT BE HELPFUL. Not boost our own ego's. KE0VH Also an RF engineer for many years. Again, The proof is in the QSO's made. | ||
| N0TONE | 2002-09-12 | |
|---|---|---|
| RE: Small EH Antenna | ||
| W7KWS, thanks for the patent info. I was aware of the CFA patent, but the EH does not fit that category. The CFA patent is very clear that the transmitter power is split into two separate signal, which have independently adjustable amplitude and phase. There are seperate elements for creating the E and H fields. Therefore, the drive network has two output ports - four wires. The EH antenna, however, does not include this critical item (the patent is clear on this - if you do not split the drive, the patent does not cover the antenna). In the EH antenna, only one port (two wires) excite the antenna, thus preventing separate control of amplitude and phase for the separate elements creating E and H. In fact, in the EH antenna, there are no such separate elements. AM Reply to a comment by : W7KWS on 2002-09-11 The U.S. Patent No. 5,155,495 seems to cover this antenna. If not right on target, it sure seems close. You can download the text and images at the U.S. Patent and Trademark site. The URL is: http://patft.uspto.gov/netahtml/srchnum.htm 73, Bob Reply to a comment by : IK5IIR on 2002-09-11 To Dr. Grover here we go....the ego of the "doctor" was hit. I am sorry but many of your sentences are wrong 1) the EH antenna can not be modeled with program that don't consider the current displacement. those program doesn't work with EH. 2) Poynting says S= EXH that symbol X means that the fields are orthogonal in SPACE (90 degrees apart) and in TIME phase. BOTH OF THEM. 3) The eh antenna ,like a vertical dipole, has the H field and the E field 90 degrees apart in space .The displacement current produce the H field. Then the matching /phasing network is responsible for the time alignement 4 I never said the impedance is resisitive...wrong! I told you the RR is 2360 ohm. the impedance of a typical eh is 2360 -J4000 5) the phase of the voltage in the cylinders is +90 and -90 or 180 degrees apart. BUT the network doesn't produce any phase shift of the voltage from the input and the output. only current delay. (phase shift) 6) I have no doubt you didn't find anything on the network. there must be a special phase shift condition. I have no idea what you built. as many experimenters say, the antenna works, if your didn't you had not an eh antenna. 7) there are not so many antennas around. i got many times S 9+ using only 80 watts from USA. I repeat i made long comparisons against verticals (full size)and I never get differences. I described to you a lot of features. You didn't comment. probabily you have not read them... is the same story...is not on the books hence it can not work. everybody is free to believe what he wants. bythe way..the supe C antenna is NOT a cfa antenna ! is just a traditional resonant antenna with a small L and a big C to achieve the resonance. the eh antenna is much smaller , but it works with a phase to align the fields..is completely different. Sincerly, steve Ik5IIR Reply to a comment by : N0GV on 2002-09-11 Oh, yes, I forgot. The guys at GAP have a neat antenna which will actually work. It is a crossed field antenna, the "Super C." Note that the current is carried in the short rod between the screen plate and "can" and that the E-Field is virtually vertical with the H field cylindrically symmetric in the phi direction -- hence E X H is at about 90 degrees..... No smoke, no mirrors, just good ol Uncle Max hard at work! Grover Reply to a comment by : N0GV on 2002-09-11 KE0VH please can the personal attacks! I've no ego to boost here -- this guy has spouted bull and folks are swallowing it. If you are an RF engineer please look at what is claimed and then look at what you can document. 1) I've made "similar" structures and put them on a network analyzer and they just won't fly. 2) I've modelled these things using FDTD and MOM based simulation programs for RF and the NEC based (MOM - type) software tools and they confirmed the results from (1) above. 3) I've yet to hear ANY DX from anyone using one of these and I'm on the air on 20m about 1-2 hours per night. Signals from Italy are booming in here at 10-20 dB over S-9 on a dipole from 3 element Yagis -- this antenna should, if it worked as claimed, be at S-9 or so. Funny, I can hear an S-5 from India and an S-3 from the Pacific, whay can't I find even ONE person using one of these on the band? 4) 2300 Ohms feedpoint impedance REAL part with zero ohms reactive is claimed (resistive)! How is that related to radiation resistance? It is not necessarily related at all -- all it indicates is a very high Q factor in the feed network! What we can say from that is that the BW is likely quite small! 5) Depending on SPATIAL orientation of the conductors we get a SPATIAL phasing of E and H as well as the time domain phasing described by the author. Poynting's theorem dictates that the SPATIAL phase relationship between the E and H fields dictates propagation not just the TIME phasing. What this guy is claiming is that by driving the two sides 180 degrees apart in phase he is transmitting power out -- this is specious as the feedline is already 180 degrees shifted making his radiators IN PHASE and virtually colocated -- hence cancellation of the Electromagnetic wave is indicated. 6) If you want to call this a short fat dipole go right ahead, that model is correct for the critter. Where the BIG spatial problem arises is in the H or B field which, on a long dipole, is modelled as being cylindrical in shape with the E-field orthogonal to it. If you look at a very short wire (or a short Fat wire) the H field is not truly cylindrical at the ends but is dipole-like in form yet the E field is still Z axis directed along the length of the wire making the SPATIAL angle between the E and H field in the all-critical High E-field gap less than 90 degrees thus reducing propagation efficiency dramaticly. In short, this is a non-starter! Sorry, Grover Larkins Reply to a comment by : KE0VH on 2002-09-11 Dr. Grover, If you don't like the idea, you certainly don't have to use it. Have you even built one and tried it? Again, the long and short of it is IT WORKS. Maybe not as well as the monoband vertical or beam as we all know it, but it works. The proof is in the QSO's made. Some of us have neither the money, space or time to have the antenna's and setups AND the time to be so critical of the experimental spirit. Chill out.... The idea here is to SHARE AN IDEA THAT MIGHT BE HELPFUL. Not boost our own ego's. KE0VH Also an RF engineer for many years. Again, The proof is in the QSO's made. | ||
| N0GV | 2002-09-12 | |
|---|---|---|
| RE: Small EH Antenna | ||
| Replying to "NOTONE" I'd say that the Gap antenna is not a pure CFA but since the majority of the current is in the mast and since the screen plate and the bottom of the "can" form a parallel plate capacitor the thing is, in effect a hybrid CFA design -- true, pure CFA it is not, you are correct but I really did not want to muddy the waters any more than necessary. You are correct HFSS and the Zeland suites can and will model this antenna well. Likewise you are correct that it is effectively a short fat dipole..... I guess I dropped enough hints on that in my last posting ;-) Enjoyed your comments! As for "Steve" --- sorry mate, you're so dumb if you were a dog you'd try to tree a skunk! Please get real and stop the BS -- I've got a good half dozen antenna modelling programs and fully half of them are for 3-d structures and several are Finite-Difference-Time Domain in nature. Good luck and WHEN you get your antenna to work I'll look forward to hearing it on the band. I'll leave you with one last word just to illustrate my point: Radiation resistance IS real resistance as far as your circuit goes.... Enjoy, Grover Larkins Reply to a comment by : N0TONE on 2002-09-11 Grover I was with you until you called the Super-C a CFA. Gap has never made that claim, and my modelling of it (Ansoft HFSS) shows that it can also be analyzed as a vertically-oriented end-loaded short dipole. The measurements I've done with the antenna (admittedly not perfect, because of the usual problems developing a "range" for HF measurements) seem to substantiate the modelling. You have hit upon several points which I attempted to make earlier. The claims about the "phasing" network are clearly bogus. The antenna has a drive point impedance, and the relationship between I and V are set by that impedance. No matching network (even if you call it a 'phasing network' can alter that relationship in a one-port device. Interestingly, IK5IIR's posting on how the phasing network operates is an exact description of one way that you'd make a simple impedance matching network for a complex impedance, and nothing more. But does the proposed construction article have merit? I think so. My own short fat dipole experiments used thin copper as a conductor. Even if only a few mils thick, a three to six inch diamater copper conductor (aluminum is not a lot less conductive) has a LOT of surface area and very low RF resistance as a result. It also has plenty of heat radiating surface. My short 40 meter vertical dipole (6 feet tall) does not get warm to the touch, with 1kW CW into it. I've had corona arcing at the ends, and have cured that with copper hemispheres brazed onto it. DX performance is superior to a comparison antenna which is admittedly a compromise. My full-size 40 meter vertical is ground-mounted, and even with the radials, a fair amount of the near fields have to suffer penetrating poor soil. I top-load this antenna and "make it work" on 80 meters. The results of the short fat dipole are better by a few dB (when I factor out the "wow" effect from the other end of the link), and I "blame" that on the fact that the short fat dipole sits about 15 feet in the air, making it less fussy about having a good ground underneath, than the vertical which sits on the ground. Matching for my short fat dipole is via motor-driven variable inductor and broadband transformer, installed at the antenna, inside the copper tubes. In fact, the copper tube diameter was chosen not for any perceived electromagnetic need, but because it fit the matching components. By the way, I have been completely unable to find the so-called patent on this antenna. In the QRZ.COM article, the claim was made that there was a patent on the EH that was separate from the CFA. If anybody knows what the patent number is, I'd like to see it. For the time being, I'll assume the claim was false. AM Reply to a comment by : N0GV on 2002-09-11 Oh, yes, I forgot. The guys at GAP have a neat antenna which will actually work. It is a crossed field antenna, the "Super C." Note that the current is carried in the short rod between the screen plate and "can" and that the E-Field is virtually vertical with the H field cylindrically symmetric in the phi direction -- hence E X H is at about 90 degrees..... No smoke, no mirrors, just good ol Uncle Max hard at work! Grover Reply to a comment by : N0GV on 2002-09-11 KE0VH please can the personal attacks! I've no ego to boost here -- this guy has spouted bull and folks are swallowing it. If you are an RF engineer please look at what is claimed and then look at what you can document. 1) I've made "similar" structures and put them on a network analyzer and they just won't fly. 2) I've modelled these things using FDTD and MOM based simulation programs for RF and the NEC based (MOM - type) software tools and they confirmed the results from (1) above. 3) I've yet to hear ANY DX from anyone using one of these and I'm on the air on 20m about 1-2 hours per night. Signals from Italy are booming in here at 10-20 dB over S-9 on a dipole from 3 element Yagis -- this antenna should, if it worked as claimed, be at S-9 or so. Funny, I can hear an S-5 from India and an S-3 from the Pacific, whay can't I find even ONE person using one of these on the band? 4) 2300 Ohms feedpoint impedance REAL part with zero ohms reactive is claimed (resistive)! How is that related to radiation resistance? It is not necessarily related at all -- all it indicates is a very high Q factor in the feed network! What we can say from that is that the BW is likely quite small! 5) Depending on SPATIAL orientation of the conductors we get a SPATIAL phasing of E and H as well as the time domain phasing described by the author. Poynting's theorem dictates that the SPATIAL phase relationship between the E and H fields dictates propagation not just the TIME phasing. What this guy is claiming is that by driving the two sides 180 degrees apart in phase he is transmitting power out -- this is specious as the feedline is already 180 degrees shifted making his radiators IN PHASE and virtually colocated -- hence cancellation of the Electromagnetic wave is indicated. 6) If you want to call this a short fat dipole go right ahead, that model is correct for the critter. Where the BIG spatial problem arises is in the H or B field which, on a long dipole, is modelled as being cylindrical in shape with the E-field orthogonal to it. If you look at a very short wire (or a short Fat wire) the H field is not truly cylindrical at the ends but is dipole-like in form yet the E field is still Z axis directed along the length of the wire making the SPATIAL angle between the E and H field in the all-critical High E-field gap less than 90 degrees thus reducing propagation efficiency dramaticly. In short, this is a non-starter! Sorry, Grover Larkins Reply to a comment by : KE0VH on 2002-09-11 Dr. Grover, If you don't like the idea, you certainly don't have to use it. Have you even built one and tried it? Again, the long and short of it is IT WORKS. Maybe not as well as the monoband vertical or beam as we all know it, but it works. The proof is in the QSO's made. Some of us have neither the money, space or time to have the antenna's and setups AND the time to be so critical of the experimental spirit. Chill out.... The idea here is to SHARE AN IDEA THAT MIGHT BE HELPFUL. Not boost our own ego's. KE0VH Also an RF engineer for many years. Again, The proof is in the QSO's made. | ||
| W7KWS | 2002-09-11 | |
|---|---|---|
| RE: Small EH Antenna | ||
| The U.S. Patent No. 5,155,495 seems to cover this antenna. If not right on target, it sure seems close. You can download the text and images at the U.S. Patent and Trademark site. The URL is: http://patft.uspto.gov/netahtml/srchnum.htm 73, Bob Reply to a comment by : IK5IIR on 2002-09-11 To Dr. Grover here we go....the ego of the "doctor" was hit. I am sorry but many of your sentences are wrong 1) the EH antenna can not be modeled with program that don't consider the current displacement. those program doesn't work with EH. 2) Poynting says S= EXH that symbol X means that the fields are orthogonal in SPACE (90 degrees apart) and in TIME phase. BOTH OF THEM. 3) The eh antenna ,like a vertical dipole, has the H field and the E field 90 degrees apart in space .The displacement current produce the H field. Then the matching /phasing network is responsible for the time alignement 4 I never said the impedance is resisitive...wrong! I told you the RR is 2360 ohm. the impedance of a typical eh is 2360 -J4000 5) the phase of the voltage in the cylinders is +90 and -90 or 180 degrees apart. BUT the network doesn't produce any phase shift of the voltage from the input and the output. only current delay. (phase shift) 6) I have no doubt you didn't find anything on the network. there must be a special phase shift condition. I have no idea what you built. as many experimenters say, the antenna works, if your didn't you had not an eh antenna. 7) there are not so many antennas around. i got many times S 9+ using only 80 watts from USA. I repeat i made long comparisons against verticals (full size)and I never get differences. I described to you a lot of features. You didn't comment. probabily you have not read them... is the same story...is not on the books hence it can not work. everybody is free to believe what he wants. bythe way..the supe C antenna is NOT a cfa antenna ! is just a traditional resonant antenna with a small L and a big C to achieve the resonance. the eh antenna is much smaller , but it works with a phase to align the fields..is completely different. Sincerly, steve Ik5IIR Reply to a comment by : N0GV on 2002-09-11 Oh, yes, I forgot. The guys at GAP have a neat antenna which will actually work. It is a crossed field antenna, the "Super C." Note that the current is carried in the short rod between the screen plate and "can" and that the E-Field is virtually vertical with the H field cylindrically symmetric in the phi direction -- hence E X H is at about 90 degrees..... No smoke, no mirrors, just good ol Uncle Max hard at work! Grover Reply to a comment by : N0GV on 2002-09-11 KE0VH please can the personal attacks! I've no ego to boost here -- this guy has spouted bull and folks are swallowing it. If you are an RF engineer please look at what is claimed and then look at what you can document. 1) I've made "similar" structures and put them on a network analyzer and they just won't fly. 2) I've modelled these things using FDTD and MOM based simulation programs for RF and the NEC based (MOM - type) software tools and they confirmed the results from (1) above. 3) I've yet to hear ANY DX from anyone using one of these and I'm on the air on 20m about 1-2 hours per night. Signals from Italy are booming in here at 10-20 dB over S-9 on a dipole from 3 element Yagis -- this antenna should, if it worked as claimed, be at S-9 or so. Funny, I can hear an S-5 from India and an S-3 from the Pacific, whay can't I find even ONE person using one of these on the band? 4) 2300 Ohms feedpoint impedance REAL part with zero ohms reactive is claimed (resistive)! How is that related to radiation resistance? It is not necessarily related at all -- all it indicates is a very high Q factor in the feed network! What we can say from that is that the BW is likely quite small! 5) Depending on SPATIAL orientation of the conductors we get a SPATIAL phasing of E and H as well as the time domain phasing described by the author. Poynting's theorem dictates that the SPATIAL phase relationship between the E and H fields dictates propagation not just the TIME phasing. What this guy is claiming is that by driving the two sides 180 degrees apart in phase he is transmitting power out -- this is specious as the feedline is already 180 degrees shifted making his radiators IN PHASE and virtually colocated -- hence cancellation of the Electromagnetic wave is indicated. 6) If you want to call this a short fat dipole go right ahead, that model is correct for the critter. Where the BIG spatial problem arises is in the H or B field which, on a long dipole, is modelled as being cylindrical in shape with the E-field orthogonal to it. If you look at a very short wire (or a short Fat wire) the H field is not truly cylindrical at the ends but is dipole-like in form yet the E field is still Z axis directed along the length of the wire making the SPATIAL angle between the E and H field in the all-critical High E-field gap less than 90 degrees thus reducing propagation efficiency dramaticly. In short, this is a non-starter! Sorry, Grover Larkins Reply to a comment by : KE0VH on 2002-09-11 Dr. Grover, If you don't like the idea, you certainly don't have to use it. Have you even built one and tried it? Again, the long and short of it is IT WORKS. Maybe not as well as the monoband vertical or beam as we all know it, but it works. The proof is in the QSO's made. Some of us have neither the money, space or time to have the antenna's and setups AND the time to be so critical of the experimental spirit. Chill out.... The idea here is to SHARE AN IDEA THAT MIGHT BE HELPFUL. Not boost our own ego's. KE0VH Also an RF engineer for many years. Again, The proof is in the QSO's made. | ||
| IK5IIR | 2002-09-11 | |
|---|---|---|
| RE: Small EH Antenna | ||
| To Dr. Grover here we go....the ego of the "doctor" was hit. I am sorry but many of your sentences are wrong 1) the EH antenna can not be modeled with program that don't consider the current displacement. those program doesn't work with EH. 2) Poynting says S= EXH that symbol X means that the fields are orthogonal in SPACE (90 degrees apart) and in TIME phase. BOTH OF THEM. 3) The eh antenna ,like a vertical dipole, has the H field and the E field 90 degrees apart in space .The displacement current produce the H field. Then the matching /phasing network is responsible for the time alignement 4 I never said the impedance is resisitive...wrong! I told you the RR is 2360 ohm. the impedance of a typical eh is 2360 -J4000 5) the phase of the voltage in the cylinders is +90 and -90 or 180 degrees apart. BUT the network doesn't produce any phase shift of the voltage from the input and the output. only current delay. (phase shift) 6) I have no doubt you didn't find anything on the network. there must be a special phase shift condition. I have no idea what you built. as many experimenters say, the antenna works, if your didn't you had not an eh antenna. 7) there are not so many antennas around. i got many times S 9+ using only 80 watts from USA. I repeat i made long comparisons against verticals (full size)and I never get differences. I described to you a lot of features. You didn't comment. probabily you have not read them... is the same story...is not on the books hence it can not work. everybody is free to believe what he wants. bythe way..the supe C antenna is NOT a cfa antenna ! is just a traditional resonant antenna with a small L and a big C to achieve the resonance. the eh antenna is much smaller , but it works with a phase to align the fields..is completely different. Sincerly, steve Ik5IIR Reply to a comment by : N0GV on 2002-09-11 Oh, yes, I forgot. The guys at GAP have a neat antenna which will actually work. It is a crossed field antenna, the "Super C." Note that the current is carried in the short rod between the screen plate and "can" and that the E-Field is virtually vertical with the H field cylindrically symmetric in the phi direction -- hence E X H is at about 90 degrees..... No smoke, no mirrors, just good ol Uncle Max hard at work! Grover Reply to a comment by : N0GV on 2002-09-11 KE0VH please can the personal attacks! I've no ego to boost here -- this guy has spouted bull and folks are swallowing it. If you are an RF engineer please look at what is claimed and then look at what you can document. 1) I've made "similar" structures and put them on a network analyzer and they just won't fly. 2) I've modelled these things using FDTD and MOM based simulation programs for RF and the NEC based (MOM - type) software tools and they confirmed the results from (1) above. 3) I've yet to hear ANY DX from anyone using one of these and I'm on the air on 20m about 1-2 hours per night. Signals from Italy are booming in here at 10-20 dB over S-9 on a dipole from 3 element Yagis -- this antenna should, if it worked as claimed, be at S-9 or so. Funny, I can hear an S-5 from India and an S-3 from the Pacific, whay can't I find even ONE person using one of these on the band? 4) 2300 Ohms feedpoint impedance REAL part with zero ohms reactive is claimed (resistive)! How is that related to radiation resistance? It is not necessarily related at all -- all it indicates is a very high Q factor in the feed network! What we can say from that is that the BW is likely quite small! 5) Depending on SPATIAL orientation of the conductors we get a SPATIAL phasing of E and H as well as the time domain phasing described by the author. Poynting's theorem dictates that the SPATIAL phase relationship between the E and H fields dictates propagation not just the TIME phasing. What this guy is claiming is that by driving the two sides 180 degrees apart in phase he is transmitting power out -- this is specious as the feedline is already 180 degrees shifted making his radiators IN PHASE and virtually colocated -- hence cancellation of the Electromagnetic wave is indicated. 6) If you want to call this a short fat dipole go right ahead, that model is correct for the critter. Where the BIG spatial problem arises is in the H or B field which, on a long dipole, is modelled as being cylindrical in shape with the E-field orthogonal to it. If you look at a very short wire (or a short Fat wire) the H field is not truly cylindrical at the ends but is dipole-like in form yet the E field is still Z axis directed along the length of the wire making the SPATIAL angle between the E and H field in the all-critical High E-field gap less than 90 degrees thus reducing propagation efficiency dramaticly. In short, this is a non-starter! Sorry, Grover Larkins Reply to a comment by : KE0VH on 2002-09-11 Dr. Grover, If you don't like the idea, you certainly don't have to use it. Have you even built one and tried it? Again, the long and short of it is IT WORKS. Maybe not as well as the monoband vertical or beam as we all know it, but it works. The proof is in the QSO's made. Some of us have neither the money, space or time to have the antenna's and setups AND the time to be so critical of the experimental spirit. Chill out.... The idea here is to SHARE AN IDEA THAT MIGHT BE HELPFUL. Not boost our own ego's. KE0VH Also an RF engineer for many years. Again, The proof is in the QSO's made. | ||
| N0TONE | 2002-09-11 | |
|---|---|---|
| RE: Small EH Antenna | ||
| Grover I was with you until you called the Super-C a CFA. Gap has never made that claim, and my modelling of it (Ansoft HFSS) shows that it can also be analyzed as a vertically-oriented end-loaded short dipole. The measurements I've done with the antenna (admittedly not perfect, because of the usual problems developing a "range" for HF measurements) seem to substantiate the modelling. You have hit upon several points which I attempted to make earlier. The claims about the "phasing" network are clearly bogus. The antenna has a drive point impedance, and the relationship between I and V are set by that impedance. No matching network (even if you call it a 'phasing network' can alter that relationship in a one-port device. Interestingly, IK5IIR's posting on how the phasing network operates is an exact description of one way that you'd make a simple impedance matching network for a complex impedance, and nothing more. But does the proposed construction article have merit? I think so. My own short fat dipole experiments used thin copper as a conductor. Even if only a few mils thick, a three to six inch diamater copper conductor (aluminum is not a lot less conductive) has a LOT of surface area and very low RF resistance as a result. It also has plenty of heat radiating surface. My short 40 meter vertical dipole (6 feet tall) does not get warm to the touch, with 1kW CW into it. I've had corona arcing at the ends, and have cured that with copper hemispheres brazed onto it. DX performance is superior to a comparison antenna which is admittedly a compromise. My full-size 40 meter vertical is ground-mounted, and even with the radials, a fair amount of the near fields have to suffer penetrating poor soil. I top-load this antenna and "make it work" on 80 meters. The results of the short fat dipole are better by a few dB (when I factor out the "wow" effect from the other end of the link), and I "blame" that on the fact that the short fat dipole sits about 15 feet in the air, making it less fussy about having a good ground underneath, than the vertical which sits on the ground. Matching for my short fat dipole is via motor-driven variable inductor and broadband transformer, installed at the antenna, inside the copper tubes. In fact, the copper tube diameter was chosen not for any perceived electromagnetic need, but because it fit the matching components. By the way, I have been completely unable to find the so-called patent on this antenna. In the QRZ.COM article, the claim was made that there was a patent on the EH that was separate from the CFA. If anybody knows what the patent number is, I'd like to see it. For the time being, I'll assume the claim was false. AM Reply to a comment by : N0GV on 2002-09-11 Oh, yes, I forgot. The guys at GAP have a neat antenna which will actually work. It is a crossed field antenna, the "Super C." Note that the current is carried in the short rod between the screen plate and "can" and that the E-Field is virtually vertical with the H field cylindrically symmetric in the phi direction -- hence E X H is at about 90 degrees..... No smoke, no mirrors, just good ol Uncle Max hard at work! Grover Reply to a comment by : N0GV on 2002-09-11 KE0VH please can the personal attacks! I've no ego to boost here -- this guy has spouted bull and folks are swallowing it. If you are an RF engineer please look at what is claimed and then look at what you can document. 1) I've made "similar" structures and put them on a network analyzer and they just won't fly. 2) I've modelled these things using FDTD and MOM based simulation programs for RF and the NEC based (MOM - type) software tools and they confirmed the results from (1) above. 3) I've yet to hear ANY DX from anyone using one of these and I'm on the air on 20m about 1-2 hours per night. Signals from Italy are booming in here at 10-20 dB over S-9 on a dipole from 3 element Yagis -- this antenna should, if it worked as claimed, be at S-9 or so. Funny, I can hear an S-5 from India and an S-3 from the Pacific, whay can't I find even ONE person using one of these on the band? 4) 2300 Ohms feedpoint impedance REAL part with zero ohms reactive is claimed (resistive)! How is that related to radiation resistance? It is not necessarily related at all -- all it indicates is a very high Q factor in the feed network! What we can say from that is that the BW is likely quite small! 5) Depending on SPATIAL orientation of the conductors we get a SPATIAL phasing of E and H as well as the time domain phasing described by the author. Poynting's theorem dictates that the SPATIAL phase relationship between the E and H fields dictates propagation not just the TIME phasing. What this guy is claiming is that by driving the two sides 180 degrees apart in phase he is transmitting power out -- this is specious as the feedline is already 180 degrees shifted making his radiators IN PHASE and virtually colocated -- hence cancellation of the Electromagnetic wave is indicated. 6) If you want to call this a short fat dipole go right ahead, that model is correct for the critter. Where the BIG spatial problem arises is in the H or B field which, on a long dipole, is modelled as being cylindrical in shape with the E-field orthogonal to it. If you look at a very short wire (or a short Fat wire) the H field is not truly cylindrical at the ends but is dipole-like in form yet the E field is still Z axis directed along the length of the wire making the SPATIAL angle between the E and H field in the all-critical High E-field gap less than 90 degrees thus reducing propagation efficiency dramaticly. In short, this is a non-starter! Sorry, Grover Larkins Reply to a comment by : KE0VH on 2002-09-11 Dr. Grover, If you don't like the idea, you certainly don't have to use it. Have you even built one and tried it? Again, the long and short of it is IT WORKS. Maybe not as well as the monoband vertical or beam as we all know it, but it works. The proof is in the QSO's made. Some of us have neither the money, space or time to have the antenna's and setups AND the time to be so critical of the experimental spirit. Chill out.... The idea here is to SHARE AN IDEA THAT MIGHT BE HELPFUL. Not boost our own ego's. KE0VH Also an RF engineer for many years. Again, The proof is in the QSO's made. | ||
| N0GV | 2002-09-11 | |
|---|---|---|
| RE: Small EH Antenna | ||
| Oh, yes, I forgot. The guys at GAP have a neat antenna which will actually work. It is a crossed field antenna, the "Super C." Note that the current is carried in the short rod between the screen plate and "can" and that the E-Field is virtually vertical with the H field cylindrically symmetric in the phi direction -- hence E X H is at about 90 degrees..... No smoke, no mirrors, just good ol Uncle Max hard at work! Grover Reply to a comment by : N0GV on 2002-09-11 KE0VH please can the personal attacks! I've no ego to boost here -- this guy has spouted bull and folks are swallowing it. If you are an RF engineer please look at what is claimed and then look at what you can document. 1) I've made "similar" structures and put them on a network analyzer and they just won't fly. 2) I've modelled these things using FDTD and MOM based simulation programs for RF and the NEC based (MOM - type) software tools and they confirmed the results from (1) above. 3) I've yet to hear ANY DX from anyone using one of these and I'm on the air on 20m about 1-2 hours per night. Signals from Italy are booming in here at 10-20 dB over S-9 on a dipole from 3 element Yagis -- this antenna should, if it worked as claimed, be at S-9 or so. Funny, I can hear an S-5 from India and an S-3 from the Pacific, whay can't I find even ONE person using one of these on the band? 4) 2300 Ohms feedpoint impedance REAL part with zero ohms reactive is claimed (resistive)! How is that related to radiation resistance? It is not necessarily related at all -- all it indicates is a very high Q factor in the feed network! What we can say from that is that the BW is likely quite small! 5) Depending on SPATIAL orientation of the conductors we get a SPATIAL phasing of E and H as well as the time domain phasing described by the author. Poynting's theorem dictates that the SPATIAL phase relationship between the E and H fields dictates propagation not just the TIME phasing. What this guy is claiming is that by driving the two sides 180 degrees apart in phase he is transmitting power out -- this is specious as the feedline is already 180 degrees shifted making his radiators IN PHASE and virtually colocated -- hence cancellation of the Electromagnetic wave is indicated. 6) If you want to call this a short fat dipole go right ahead, that model is correct for the critter. Where the BIG spatial problem arises is in the H or B field which, on a long dipole, is modelled as being cylindrical in shape with the E-field orthogonal to it. If you look at a very short wire (or a short Fat wire) the H field is not truly cylindrical at the ends but is dipole-like in form yet the E field is still Z axis directed along the length of the wire making the SPATIAL angle between the E and H field in the all-critical High E-field gap less than 90 degrees thus reducing propagation efficiency dramaticly. In short, this is a non-starter! Sorry, Grover Larkins Reply to a comment by : KE0VH on 2002-09-11 Dr. Grover, If you don't like the idea, you certainly don't have to use it. Have you even built one and tried it? Again, the long and short of it is IT WORKS. Maybe not as well as the monoband vertical or beam as we all know it, but it works. The proof is in the QSO's made. Some of us have neither the money, space or time to have the antenna's and setups AND the time to be so critical of the experimental spirit. Chill out.... The idea here is to SHARE AN IDEA THAT MIGHT BE HELPFUL. Not boost our own ego's. KE0VH Also an RF engineer for many years. Again, The proof is in the QSO's made. | ||
| N0GV | 2002-09-11 | |
|---|---|---|
| RE: Small EH Antenna | ||
| KE0VH please can the personal attacks! I've no ego to boost here -- this guy has spouted bull and folks are swallowing it. If you are an RF engineer please look at what is claimed and then look at what you can document. 1) I've made "similar" structures and put them on a network analyzer and they just won't fly. 2) I've modelled these things using FDTD and MOM based simulation programs for RF and the NEC based (MOM - type) software tools and they confirmed the results from (1) above. 3) I've yet to hear ANY DX from anyone using one of these and I'm on the air on 20m about 1-2 hours per night. Signals from Italy are booming in here at 10-20 dB over S-9 on a dipole from 3 element Yagis -- this antenna should, if it worked as claimed, be at S-9 or so. Funny, I can hear an S-5 from India and an S-3 from the Pacific, whay can't I find even ONE person using one of these on the band? 4) 2300 Ohms feedpoint impedance REAL part with zero ohms reactive is claimed (resistive)! How is that related to radiation resistance? It is not necessarily related at all -- all it indicates is a very high Q factor in the feed network! What we can say from that is that the BW is likely quite small! 5) Depending on SPATIAL orientation of the conductors we get a SPATIAL phasing of E and H as well as the time domain phasing described by the author. Poynting's theorem dictates that the SPATIAL phase relationship between the E and H fields dictates propagation not just the TIME phasing. What this guy is claiming is that by driving the two sides 180 degrees apart in phase he is transmitting power out -- this is specious as the feedline is already 180 degrees shifted making his radiators IN PHASE and virtually colocated -- hence cancellation of the Electromagnetic wave is indicated. 6) If you want to call this a short fat dipole go right ahead, that model is correct for the critter. Where the BIG spatial problem arises is in the H or B field which, on a long dipole, is modelled as being cylindrical in shape with the E-field orthogonal to it. If you look at a very short wire (or a short Fat wire) the H field is not truly cylindrical at the ends but is dipole-like in form yet the E field is still Z axis directed along the length of the wire making the SPATIAL angle between the E and H field in the all-critical High E-field gap less than 90 degrees thus reducing propagation efficiency dramaticly. In short, this is a non-starter! Sorry, Grover Larkins Reply to a comment by : KE0VH on 2002-09-11 Dr. Grover, If you don't like the idea, you certainly don't have to use it. Have you even built one and tried it? Again, the long and short of it is IT WORKS. Maybe not as well as the monoband vertical or beam as we all know it, but it works. The proof is in the QSO's made. Some of us have neither the money, space or time to have the antenna's and setups AND the time to be so critical of the experimental spirit. Chill out.... The idea here is to SHARE AN IDEA THAT MIGHT BE HELPFUL. Not boost our own ego's. KE0VH Also an RF engineer for many years. Again, The proof is in the QSO's made. | ||
| KE0VH | 2002-09-11 | |
|---|---|---|
| Small EH Antenna | ||
| Dr. Grover, If you don't like the idea, you certainly don't have to use it. Have you even built one and tried it? Again, the long and short of it is IT WORKS. Maybe not as well as the monoband vertical or beam as we all know it, but it works. The proof is in the QSO's made. Some of us have neither the money, space or time to have the antenna's and setups AND the time to be so critical of the experimental spirit. Chill out.... The idea here is to SHARE AN IDEA THAT MIGHT BE HELPFUL. Not boost our own ego's. KE0VH Also an RF engineer for many years. Again, The proof is in the QSO's made. | ||
| N0GV | 2002-09-11 | |
|---|---|---|
| RE: Small EH Antenna | ||
| Hi Folks, Here we go again -- there is a major problem here and it is one which flat won't go away. I now understand the "phasing" which is key to this argument and there is a large venomous insect swimming in the soup. 1) Please note that circuit phase is between I and V (current and voltage)in time and that propagation is dependent on the H and E phase in space as the time and space phase are fixed in relationship with one another in a propagating wave in a non-dispersive media. 2) Steve's claims are based on the I-V phase in the circuit which are NOT equivalent with time and space phasing of the H and E fields even though he has used them as if they were! As a result the entire analysis is founded on an invalid or happenstance foundation! As for the short fat vertical dipole mentioned -- correct, it will work and do pretty well up on a PVC vent pipe if it is properly driven and matched. Bandwidth will be small (an understatement!) but efficiency can be pretty good if the conductors are large in diameter and the matching network is of high Q to reduce losses there. Getting the puppy away from the nearest 1/10 wavelength of ground will help enormously in reducing ground losses. Spatial gain (directivity) will be low ~ 3.11 dBi as there is really no help from the earth ground as it is vertical and at the null of the pattern. As for the counterpoise arguements -- I'd be more comfortable calling that working your windom's ground braid against the E-H as a ground; I'd be willing to wager that most if not all of the radiation is from the windom's shield..... After all this E-H contraption is a balanced antenna and as a result and by definition it NEEDS NO GROUND -- same as a dipole. A quarter wave vertical uses the image of the vertical conductor to replace one leg of a vertical dipole hence it REQUIRES a ground connection to work using the image in the ground plane. Please, please put a stake in this critter's heart and get on with doing something useful like electrifing your trash cans with a plastic paint bucket between them to make a really short fat dipole capable of zorching the neighbor's *#$@@^&* noisy cat when it decides to sing at 2 am. THIS will earn you the respect and admiration of your wife and family and all but one of your neighbors! It will also transmit pretty well too, better than the aluminum foil zorchomatic we've been discussing. Remember you can make an L-C circuit resonant but it does not RADIATE as the E and H fields are spatially aligned (vector cross product is ~ 0). Yes you can lose *some* E and H field as a fringing field but they have an imaginary wavevector and die off exponentially (evanescent wave). This here house was built in the middle of the quicksand pit and it's a sinkin fast! Sorry to be so blunt but it just is not a valid premise that this antenna was built on! Sincerely, Dr. Grover Larkins N0GV PS: I've appended my actual title and so on so that you may actually believe me when I say that this sort of stuff is precisely what we make our living at from 1 MHz to 100 GHz. Associate Professor and Director, Future Aerospace Science and Technology Center for Space Cryoelectronics/Advanced Communications, Florida International University, Miami, FL 33199 Reply to a comment by : N0TONE on 2002-09-07 Grover, you're sharp. You've corrected a few of my errors, but there are a few places we still don't see eye to eye. Call it differing viewpoints; I believe we are both attempting to achieve the same thing - an accurate understanding. To wit: > >>I am aware that physically small antennas can be made with very decent radiation efficiency but that they almost invariably wind up as point-source radiators<< >>"Except that they all have nulls off the end." >Actually the null can be vanishingly small and neglected if the radiator is short enough. These are. Even a "vanishingly small" null has finite "beamwidth". Look at the gain of a very short vertical, say, 20 degrees from vertical, and then a high dipole at the same angle. The dipole is still delivering a LOT of energy straight up. However, the original point is still valid. Anybody who has room for a full-length dipole isn't paying any attention to this discussion anyway, so the comparison is irrelevant. >> >>A low (below lambda over 4) dipole can have a gain in excess of 5 dBi in its major lobe quite easily. << >>"At only lambda/4 off the ground, though, that main lobe is uselessly straight up. Ten minutes with NEC will show you that in the useful radiation angles from 5 to about 20 degrees, a dipole at only 1/4 wave off the lossy ground has negative gain compared with a point source." >>Not true, at an angle of 70 degrees from the vertical (20 degrees from the horizontal the gain is 3.11 dBi for a horizontal dipole. The 0 dBi angle is 13 Degrees above the horizon. For a vertical dipole (what we are sort of discussing with the EH design) the max gain is 0.41 dBi at 19 degrees above the horizon over reasonable ground (Eps = 13, sigma = 0.005). Grover, please check your simulator. Many of the NEC variants do a very bad job of performance predictions over REAL ground. I have done ground measurements in several places across the US, and every sample I've taken has worse conductivity than the "poor" selection in every NEC I've tried. My favourite prediction tool is a massive 3D electromagnetic simulator engine that runs on a massed PC array at UCal. Every time I build an antenna that I've modelled using that code, the measurements meet the predictions. This is not the case with NEC, which is admittedly not good with grounds. You should check your numbers, too. A dipole in free space does not have 3.15dBi at ANY angle. The same dipole can only achieve that number if it's placed over a ground model which is far better than anything that's practical. A sanity check on your simulator would be to make sure you achieve 2.15 dBi on the horizon for a free-space dipole, and that as you bring that antenna closer to your modelled ground, that number just goes down, and down, and down. There should be no angle at which the performance over ground is better than in free space, because with REAL ground, there is no such angle. 20 degrees, by the way, is only barely useful. >>Agreed. Still all in all, less gain available than a high horiz. dipole. Trade-off point is lambda over four in height for the dipole. Higer makes the dipole noticibly better than a vertical. Disagree. You seem to think that 20 degrees is a useful angle. Your target should be below 10 degrees, which requires the dipole to be at least halfwave high. There's a reason why 40 meter dipoles "come to life" at 70 feet in height, and 20 meter dipoles do the same at 35 feet. >>>>"If the antenna gets warm in operation, then it's lossy. The effort spent to reduce loss in the goal of improved "gain" will also yield an antenna that will not zorch itself. They go together." >>True indeed but a couple of hundred amperes of rf through a 8" wide piece of aluminum foil wound on a cardboard tube is a zorch recipe if ever there was one! I suspect you haven't tried it. Taking skin effect into account, what is the RF resistance of a 2" diameter aluminum tube? A very small fraction of an ohm. The actual heating loss of that tube can easily be below 10 watts, even with hundreds of amps flowing through it. We should be thankful for this, otherwise solid state RF power amplifiers wouldn't work, because that's the sort of current density we create in the bond wires inside the RF output transistors in our rigs. If 2 amps of RF is safe in a bond wire that's only 0.0007 inches in diameter, then I'm quite comfortable with 200 amps in a 2" diamter tube. Besides, the reports on heating in the so-called EH antennas have never mentioned the tubes heating - it's always been the resonating inductors. >>>>"Uh, maybe. The "typical" auto antenna intentionally uses conductor loss to match to 50 ohms. If the antenna were built with a low-loss loading coil, the base impedance would be low, about 8 ohms in the example you give. To "fix" this, antennas such as the Hamstik intentionally use small- gauge wire for the loading coil, to add loss resistance. That means the base drive point resistance is 50 ohms, making the transceiver happy. The more expensive screwdriver-type mobile antennas do use a low-loss coil, and deal with the low drive-point impedance with a matching transformer. That's why they work better, particularly on the lower frequencies." >>Actually the Hustler brand short verticals will do 1kW - these are what I was mostly referring to not the Hamsticks, my error. I've melted Hustler 40 meter resonators with 500 watts. The point is this: IF an 8 foot 40 meter antenna is 50 ohms resistive at the feedpoint, THEN the matching is being created by loss. Hustler's design does not reduce the loss, it only makes the surfaces larger so that they do not rise as much in temperature at the same dissipated power. An 8 foot long 40 meter whip SHOULD measure about 8-12 ohms at the base, and require a matching network at that point. >>>>Static capacitance is not a good indicator of rf capacitance -- on the other hand the numbers seem low even for static capacitance ie. 25 cm separation on a 10 sq meter parallel plate capacitor = 350 pF and fringing fields on a car body should at least triple that value. <<< Who said anything about static capacitance? I made my measurements at RF using a network analyzer. And, my vehicle is a truck. There is very little metal that's only 25 cm (10 inches) off the ground. Most of the vehicle is higher than that. Fringing fields on a large surface are completely ignorable - they're only significant on small surfaces. Even on the little 2.4mm RF connectors that I routinely analyze, they only account for a 10% error in capacitance, nowhere near 3X. Let's see, the truck is about 5ft wide and 11 ft long, that's 55 sq feet, so your 10 sq meter estimate is about 2X too high. >>>Actually they [evansecent modes] are parasitic loss modes and do take significant power from the source. Propogation with exponentially decaying amplitude is the proper definition. I'm curious - where does the power go? If it's lossy, that means something gets warm. Is it the air itself that gets warm? >>>"I'd never considered an evanescent mode in propagation in semi-free space before. I'll have to look this one up or model it, but I sense that this is a misconception altogether." >Tis slippery as the dickens as most waveguide texts try really hard to ignore it as a near field, non propagating mode... Wrong. I used to teach electromagnetics, and non-propagating evanescent modes INSIDE WAVEGUIDE were one of the first topics they introduced with waveguides. I've never seen a text that did not explicitly discuss them. Speaking of which, I did some analysis using a 3D simulator of waveguide modes. What turns out, is that in waveguide, the evanescent modes do not take any power at all. If the waveguide is long enough, they're simply a reflection back to the source. If the waveguide is short enough, some of the energy makes it to the other end, and can be coupled out, and that will change the apparent (frequency dependent) impedance at the input side of the waveguide. Still, that does not mean the same thing will happen in "ether". In a waveguide, evansecent modes are those where the waveguide dimensions are too small to allow propagation for that mode. I just can't imagine such a mode in free space. >>>>>>In truth, a relatively simple, stealth vertical will work better than the E- H.<< >>>>"No. The EH IS a relatively simply vertical stealth antenna. It is only the explanation of it that's attempting to make it complicated." >>Simple and inefficient.... As yet, this is the fact we're trying to understand. If they get hot, they're inefficient. If not, they're efficient, although probably not optimal in terms of radiation pattern. >>>>"If your house is new enough to have PVC downspouts, then it also has a nice, solidly conductive, aluminum sheath just underneath the siding. How effective will your 1/4 wave 20 meter vertical be when mounted 6" away from a solid sheet of aluminum? You need to get the antenna (whether "EH", vertical, etc) away from large solid conductors like that." >>>>Aluminum -- they still use aluminum? ;-) Figured wood siding or plastic -- correct, aluminum is no good! I'm not talking about the siding. UNDERNEATH the siding, there is an insulating layer, made of closed-cell foam, which is laminated with aluminum on both sides. This is an energy-efficiency requirement in most states (California being one exception - environmental consciousness here is in name only - if you can't see it, they don't do it). If you remove your wood siding, you will have exposed the aluminum underlayer, sometimes called the sheath. This aluminized layer was a building requirement in 1988 in Georgia, 1982 in Colorado, and 1978 in Michigan. I only know those data points because in those years, I was involved to one extent or another, in buildling a house in those states. You can buy this material from your local Home Depot as "rigid insulation". You can get it without the aluminum skins, but for new home construction, you're required to use it with the skins, because they form a radiant barrier. This stuff is just under your wood siding. >>>>"Watering won't help. The earth is too poor a conductor, and watering may improve it, but it's still too poor. In models and experiments, the amount of salt and other minerals required to make moist soil (or even a body of water) usefully conductive would kill any plant life." >>>>Sure it does -- rain water becomes far more conductive once it hits the pavement or lawn -- sigmas of 0.12 -0.2 are attainable -- not salt but CO2 and other stuff dissolved minerals, organic acid salts etc. will make it conductive. A sigma of 0.12 - 0.2 is worthless as a ground for a vertical. If your simulator allows you to directly enter the conductivity, you'll see that there is a dramatic difference merely going from a copper sheet to stainless steel under a vertical. To a vertical, a sigma of 0.12 - 0.2 may as well be a layer of carbon. You'd actually be better off with a sigma of 0.000, as it would simulate free space. Again, I've made these measurements in an antenna field. Even over Georgia's high-mineral soil, which was the most conductive I've worked, the measurable differences between soil which was parched, and soil after weeks of non-stop rain, was zilch. Sure, I could measure a dramatic difference in DC resistance, and even RF resistance, between two rods driven into the ground. But the difference in radiated field strength was completely un-measurable. >>>"A well-designed antenna with conductors that are the proper size will break down from voltage arcover first - not conductor meltdown." >>True -- my point is that the E-H is not well designed due to excessive currents in Al foil! But as I, and others have noted, it's not the Al foil that gets hot - it's the matching inductors. Clearly, the loss, therefore, is not in the Al. >>>Hope this helped, >>Grover It did. Grover, why don't you try it, and report back to us at what power the cardboard/foil zorches? I have not tried cardboard and foil. My own short fat verticals are made of 20 mil copper wrapped around delrin forms, and I used integrated broadband transformers, and inductors made from soft-drawn copper tubing. Mine are not "EH", they're just short fat verticals. Not mounted 0.5 meters off the ground - that's silly - but mounted, say, on a roof vent. Try that in EZNEC and you'll see it's pretty good. In fact, while you're doing that, EZNEC will allow you to model it with 2" diameter aluminum tube - see how much (if any) efficiency reduction that causes. This is what it's all about. Discussing right down to the nitty gritty what works and what doesn't. John Krauss once told me that a physically short antenna CAN be made to work effectively as well as a full sized antenna. You just don't have as much room for errors - like using 22 gauge wire for inductors in high current areas, like the original poster said he did. Oh, yes, I did come up with a zorch mode for mine. The sharp edges of the tops of the copper conductors arced. Not a loss mechanism, just corona discharge. So I ended up copper-welding copper balls to the tops to stop that little problem! AM Reply to a comment by : N0GV on 2002-09-05 "More significantly, comparisons with low dipoles are irrelevant comparisons. One must compare the proposed EH with vertical radiators, to avoid what you then pointed out - the low dipole, because it's a horizontal radiator, has lobes and nulls in vastly different directions than a vertical radiator." Precisely. >>I am aware that physically small antennas can be made with very decent radiation efficiency but that they almost invariably wind up as point-source radiators<< "Except that they all have nulls off the end." Actually the null can be vanishingly small and neglected if the radiator is short enough. These are. >>A low (below lambda over 4) dipole can have a gain in excess of 5 dBi in its major lobe quite easily. << "At only lambda/4 off the ground, though, that main lobe is uselessly straight up. Ten minutes with NEC will show you that in the useful radiation angles from 5 to about 20 degrees, a dipole at only 1/4 wave off the lossy ground has negative gain compared with a point source." Not true, at an angle of 70 degrees from the vertical (20 degrees from the horizontal the gain is 3.11 dBi for a horizontal dipole. The 0 dBi angle is 13 Degrees above the horizon. For a vertical dipole (what we are sort of discussing with the EH design) the max gain is 0.41 dBi at 19 degrees above the horizon over reasonable ground (Eps = 13, sigma = 0.005). "A vertical radiator, even if it's quite short, has a null in the straight-up direction, and a greater percentage of its radiation is in useful directions." Not really -- the size of the null varies with the length of the conductors -- a 0.2m long by 1m long vertical dipole 0.5m above ground at 14 MHz (perfect matching presumed) has a maximum of -2.11 dBi of gain at 29 degrees over the horizon. "Most vertical installations, however, are compromised by ineffective ground systems, or lossy traps or other loading systems." Agreed. Still all in all, less gain available than a high horiz. dipole. Trade-off point is lambda over four in height for the dipole. Higer makes the dipole noticibly better than a vertical. >>As has been mentioned, current handling is a large part of the problem in these antennas and great care should be used when playing with them to keep them from zorching themselves<< "If the antenna gets warm in operation, then it's lossy. The effort spent to reduce loss in the goal of improved "gain" will also yield an antenna that will not zorch itself. They go together." True indeed but a couple of hundred amperes of rf through a 8" wide piece of aluminum foil wound on a cardboard tube is a zorch recipe if ever there was one! >>>In addition to this there is the problem of ground losses as the high currents in the antenna set up correspondingly large currents in the ground surrounding the antenna leading to losses and local heating.<<< "This problem is fixed by having an elevated feedpoint. You are correct, if you are restricting your considerations to ground-mounted verticals with the feedpoint at ground level. There are many highly successful 160 meter DX hounds who are using extremely short verticals with almost no ground system - by using elevated feed antennas." Correct -- more specifically the key is in insuring that the current distribution is such that the high current regions of the antenna are as far removed from ground as possible. A 1m long tube sitting at 0.5m above ground cannot remove the high current region far enough to alleviate this problem. >>>All of these problems are seen in the typical auto antenna which at 8' or so in length is about 45% of a full-size 1/4 wavelength vertical on 20m BUT a typical car body is VERY conductive and couples fairly well to ground (about 1000-2000pF or better static coupling depending on vehicle size etc.). This reduces ground losses considerably.<<< "Uh, maybe. The "typical" auto antenna intentionally uses conductor loss to match to 50 ohms. If the antenna were built with a low-loss loading coil, the base impedance would be low, about 8 ohms in the example you give. To "fix" this, antennas such as the Hamstik intentionally use small- gauge wire for the loading coil, to add loss resistance. That means the base drive point resistance is 50 ohms, making the transceiver happy. The more expensive screwdriver-type mobile antennas do use a low-loss coil, and deal with the low drive-point impedance with a matching transformer. That's why they work better, particularly on the lower frequencies." Actually the Hustler brand short verticals will do 1kW - these are what I was mostly referring to not the Hamsticks, my error. "Also note that the car antennas work as well as they do not because they couple to the ground but exactly the opposite - they do NOT couple to the ground. They are, in effect, an elevated-feed antenna. I drove my truck onto an aluminum sheet and measured the capacitance from truck to sheet as about 70pF, not thousands. And, when I drive over a ravine, increasing the distance from ground (and lowering the capacitance), my signal strength improves. Take a car style Hamstik, and mount it in your backyard on the ground, and feed it against, for instance a ground rod (a much better contact with ground than a vehicle body), and the results are awful. It works much better mounted on a vehicle." Static capacitance is not a good indicator of rf capacitance -- on the other hand the numbers seem low even for static capacitance ie. 25 cm separation on a 10 sq meter parallel plate capacitor = 350 pF and fringing fields on a car body should at least triple that value. >>>Also notice that radiation efficiency as defined in this thread also includes non-propogating evanescent modes which, as far as the transmission of information over long distances is concerned are a loss yet which the calculations consider a part of the propagating wave. <<< "Evanescent modes, however, are displacement fields, and consume no power from the source. At least, if the modes you're discussing are the same as an evanescent mode in a waveguide." Actually they are parasitic loss modes and do take significant power from the source. Propogation with exponentially decaying amplitude is the proper definition. "I'd never considered an evanescent mode in propagation in semi-free space before. I'll have to look this one up or model it, but I sense that this is a misconception altogether." Tis slippery as the dickens as most waveguide texts try really hard to ignore it as a near field, non propagating mode... >>In truth, a relatively simple, stealth vertical will work better than the E- H.<< "No. The EH IS a relatively simply vertical stealth antenna. It is only the explanation of it that's attempting to make it complicated." Simple and inefficient.... >>>Heck -- hiding a 1/2" copper pipe in a 1" PVC pipe or PVC downspout from a 2 story house will get you a full-size 1/4 wave vertical on 20m<<< "If your house is new enough to have PVC downspouts, then it also has a nice, solidly conductive, aluminum sheath just underneath the siding. How effective will your 1/4 wave 20 meter vertical be when mounted 6" away from a solid sheet of aluminum? You need to get the antenna (whether "EH", vertical, etc) away from large solid conductors like that." Aluminum -- they still use aluminum? ;-) Figured wood siding or plastic -- correct, aluminum is no good! >>>Gain is ~3 dBi at 12 degrees above the horizon if you manage to sneak out a few radials in the grass (watering your lawn also helps ;-) )!<<< "Watering won't help. The earth is too poor a conductor, and watering may improve it, but it's still too poor. In models and experiments, the amount of salt and other minerals required to make moist soil (or even a body of water) usefully conductive would kill any plant life." Sure it does -- rain water becomes far more conductive once it hits the pavement or lawn -- sigmas of 0.12 -0.2 are attainable -- not salt but CO2 and other stuff dissolved minerals, organic acid salts etc. will make it conductive. >>This you can load up with several kW without any fear of meltdown..... << A"s I said before, if your antenna is in any risk of meltdown, then you have not correctly determined the major sources of loss and corrected them. An efficient radiator will not melt down. It is true that the vast majority of size-reduced commercial antennas are not efficient - that's why we should be building our own." True "A well-designed antenna with conductors that are the proper size will break down from voltage arcover first - not conductor meltdown." True -- my point is that the E-H is not well designed due to excessive currents in Al foil! "I agree with Grover's implied message. Build antennas. Experiment. If you MUST hide an antenna in a PVC downspout next to your thermal sheeth, it's still better than no antenna. There is NO situation where you cannot be on HF. I have had effective antennas made with 22 gauge wire snuck underneath shingles and routed as a loop. There's always a way." >>Oh well, enjoy and happy antenna making! << "I couldn't have said it better!" >>Grover Larkins << "AM" Hope this helped, Grover Reply to a comment by : N0TONE on 2002-09-04 N0GV, good to see someone is really putting some thought into the replies. Yours get me thinking, too. >>I've seen claims which say that the E-H design out-performs low dipoles, patently incorrect and not made here. << More significantly, comparisons with low dipoles are irrelevant comparisons. One must compare the proposed EH with vertical radiators, to avoid what you then pointed out - the low dipole, because it's a horizontal radiator, has lobes and nulls in vastly different directions than a vertical radiator. >>I am aware that physically small antennas can be made with very decent radiation efficiency but that they almost invariably wind up as point-source radiators<< Except that they all have nulls off the end. >>A low (below lambda over 4) dipole can have a gain in excess of 5 dBi in its major lobe quite easily. << At only lambda/4 off the ground, though, that main lobe is uselessly straight up. Ten minutes with NEC will show you that in the useful radiation angles from 5 to about 20 degrees, a dipole at only 1/4 wave off the lossy ground has negative gain compared with a point source. A vertical radiator, even if it's quite short, has a null in the straight-up direction, and a greater percentage of its radiation is in useful directions. Most vertical installations, however, are compromised by ineffective ground systems, or lossy traps or other loading systems. >>As has been mentioned, current handling is a large part of the problem in these antennas and great care should be used when playing with them to keep them from zorching themselves<< If the antenna gets warm in operation, then it's lossy. The effort spent to reduce loss in the goal of improved "gain" will also yield an antenna that will not zorch itself. They go together. >>>In addition to this there is the problem of ground losses as the high currents in the antenna set up correspondingly large currents in the ground surrounding the antenna leading to losses and local heating.<<< This problem is fixed by having an elevated feedpoint. You are correct, if you are restricting your considerations to ground-mounted verticals with the feedpoint at ground level. There are many highly successful 160 meter DX hounds who are using extremely short verticals with almost no ground system - by using elevated feed antennas. >>>All of these problems are seen in the typical auto antenna which at 8' or so in length is about 45% of a full-size 1/4 wavelength vertical on 20m BUT a typical car body is VERY conductive and couples fairly well to ground (about 1000-2000pF or better static coupling depending on vehicle size etc.). This reduces ground losses considerably.<<< Uh, maybe. The "typical" auto antenna intentionally uses conductor loss to match to 50 ohms. If the antenna were built with a low-loss loading coil, the base impedance would be low, about 8 ohms in the example you give. To "fix" this, antennas such as the Hamstik intentionally use small-gauge wire for the loading coil, to add loss resistance. That means the base drive point resistance is 50 ohms, making the transceiver happy. The more expensive screwdriver-type mobile antennas do use a low-loss coil, and deal with the low drive-point impedance with a matching transformer. That's why they work better, particularly on the lower frequencies. Also note that the car antennas work as well as they do not because they couple to the ground but exactly the opposite - they do NOT couple to the ground. They are, in effect, an elevated-feed antenna. I drove my truck onto an aluminum sheet and measured the capacitance from truck to sheet as about 70pF, not thousands. And, when I drive over a ravine, increasing the distance from ground (and lowering the capacitance), my signal strength improves. Take a car style Hamstik, and mount it in your backyard on the ground, and feed it against, for instance a ground rod (a much better contact with ground than a vehicle body), and the results are awful. It works much better mounted on a vehicle. >>>Also notice that radiation efficiency as defined in this thread also includes non-propogating evanescent modes which, as far as the transmission of information over long distances is concerned are a loss yet which the calculations consider a part of the propagating wave. <<< Evanescent modes, however, are displacement fields, and consume no power from the source. At least, if the modes you're discussing are the same as an evanescent mode in a waveguide. I'd never considered an evanescent mode in propagation in semi-free space before. I'll have to look this one up or model it, but I sense that this is a misconception altogether. >>In truth, a relatively simple, stealth vertical will work better than the E-H.<< No. The EH IS a relatively simply vertical stealth antenna. It is only the explanation of it that's attempting to make it complicated. >>>Heck -- hiding a 1/2" copper pipe in a 1" PVC pipe or PVC downspout from a 2 story house will get you a full-size 1/4 wave vertical on 20m<<< If your house is new enough to have PVC downspouts, then it also has a nice, solidly conductive, aluminum sheath just underneath the siding. How effective will your 1/4 wave 20 meter vertical be when mounted 6" away from a solid sheet of aluminum? You need to get the antenna (whether "EH", vertical, etc) away from large solid conductors like that. >>>Gain is ~3 dBi at 12 degrees above the horizon if you manage to sneak out a few radials in the grass (watering your lawn also helps ;-) )!<<< Watering won't help. The earth is too poor a conductor, and watering may improve it, but it's still too poor. In models and experiments, the amount of salt and other minerals required to make moist soil (or even a body of water) usefully conductive would kill any plant life. >>This you can load up with several kW without any fear of meltdown..... << As I said before, if your antenna is in any risk of meltdown, then you have not correctly determined the major sources of loss and corrected them. An efficient radiator will not melt down. It is true that the vast majority of size-reduced commercial antennas are not efficient - that's why we should be building our own. A well-designed antenna with conductors that are the proper size will break down from voltage arcover first - not conductor meltdown. I agree with Grover's implied message. Build antennas. Experiment. If you MUST hide an antenna in a PVC downspout next to your thermal sheeth, it's still better than no antenna. There is NO situation where you cannot be on HF. I have had effective antennas made with 22 gauge wire snuck underneath shingles and routed as a loop. There's always a way. Want to have success with this "EH"? Build it, dump power into it and see what gets warm. Whatever gets warm, improve it. Make it larger diameter, until it no longer gets warm. If 100 watts for 5 minutes doesn't get it warm, increase the power level. If 500 watts for 5 minutes doesn't get it warm, then you've succeeded in making the efficiency good. For comparisons, by the way, a Hamstick 20 meter car antenna, after 5 minutes of 100W key-down CW, was too warm to comfortably hold my hand on. And I've worked plenty of DX on 20 CW mobile. My model shows this 20 meter Hamstick to be about 10dB down from a full sized vertical, so I think 9dB down from a full-sized, well-installed antenna is still acceptable. 100W into such an antenna would be as effective as QRP into a full sized antenna, and the QRP folks do quite well. >>Oh well, enjoy and happy antenna making! << I couldn't have said it better! >>Grover Larkins << AM Reply to a comment by : N0GV on 2002-09-03 A few comments on the topic are again in order -- I've seen claims which say that the E-H design out-performs low dipoles, patently incorrect and not made here. I am aware that physically small antennas can be made with very decent radiation efficiency but that they almost invariably wind up as point-source radiators is always overlooked as is the fact that they radiate with a spherical pattern (one and the same actually). Only 9 dB down from a dipole is almost a meaningless figure if the station happens to be ~ 500 miles (800 km) away and the high angle reflection of the E-H "outperforms" the dipole by having stations in the null of the dipole compared with the E-H. My experience with short antennas would lead me to believe that a short, low, E-H antenna would be doing quite well to have a theoretical gain of a dB or so over isotropic. A low (below lambda over 4) dipole can have a gain in excess of 5 dBi in its major lobe quite easily. As has been mentioned, current handling is a large part of the problem in these antennas and great care should be used when playing with them to keep them from zorching themselves (cardboard tubes can ignite etc....) with moderate (400+ watt power levels). In addition to this there is the problem of ground losses as the high currents in the antenna set up correspondingly large currents in the ground surrounding the antenna leading to losses and local heating. All of these problems are seen in the typical auto antenna which at 8' or so in length is about 45% of a full-size 1/4 wavelength vertical on 20m BUT a typical car body is VERY conductive and couples fairly well to ground (about 1000-2000pF or better static coupling depending on vehicle size etc.). This reduces ground losses considerably. Also notice that radiation efficiency as defined in this thread also includes non-propogating evanescent modes which, as far as the transmission of information over long distances is concerned are a loss yet which the calculations consider a part of the propagating wave. In truth, a relatively simple, stealth vertical will work better than the E-H. It will have a wider bandwidth, a lower chance of ignition and less EMI potential and you can drive it with higher power levels..... If you need gain you can even phase a couple of them together to get a couple of dB of gain!!! Heck -- hiding a 1/2" copper pipe in a 1" PVC pipe or PVC downspout from a 2 story house will get you a full-size 1/4 wave vertical on 20m and I sincerely doubt that the neighborhood covenant Nazis will even see it or object to it! Gain is ~3 dBi at 12 degrees above the horizon if you manage to sneak out a few radials in the grass (watering your lawn also helps ;-) )! This you can load up with several kW without any fear of meltdown..... Oh well, enjoy and happy antenna making! Grover Larkins Reply to a comment by : N0TONE on 2002-09-03 N0GV, I am inclined to agree re: the patent claims. However, the patent claims are written with such double-talk (among other consulting activites which I perform, are patent investigations, and the language of this one is terribly difficult to wade through -worse than most). However, I am willing to set that aside for a different discussion, to address the issue of whether this antenna can, in fact, be a viable candidate as a small-profile radiator. In your posting, you acknowledged that the antenna's radiation is 9dB down from a low dipole - and mind, you, the antenna in question was mounted below that low dipole, so the antenna in question, mounted at the same height as the low dipole may have done better. Of course, a dipole is not the best antenna to compare with, given the orthoganal radiation patterrns one expects between a horizontal dipole and this so-called EH, which is principally a vertical dipole. However, it is notable that an antenna which is only 5% of the size it "should" be (14 inches versus 33 feet, for a 1/2 wave vertical dipole on 20 meters) and yet its radiation is ONLY 9dB down. That is nothing short of remarkable. I have performed measurements on many of the commercially available mobile whips, and at 8 feet long, very few of them are "only" 9dB down. 12dB is more the order of the day. I won't go into the detailed explanation, but for comparison purposes, you can expect the run-of-the-mill, center-loaded whip or trapped dipole to have reduced efficiency, to the tune of 10 log ( (length actual / length full-size)^2). The math is easy to work out - start by predicting the real part of the drive impedance (versus length), then resonate with inductance and add series loss resistance until you're back to 50 ohms. That's how the major manufacturers do it with their various loaded whips. I always look for good ideas. In this case, the idea of using large-diameter conductors in a shortened antenna to overcome the expected extremely high currents is a wonderful idea. The patent itself is irrelevant, so it matters not whether it's valid or not. By the way, in my homebrew foreshortened "fat" dipoles, I have measured efficiencies of about 25% for an antenna which is 10% of "full size", through similar techniques of using fat conductors, but paying more attention to low-loss tuning networks than have been shown so far. N0GV, try building one. Tune it so that the SWR is low, then shove 100W into it. Find out what gets warm, then alter the design (make something fatter) and test again. You will be surprised. Here is the true test of whether you have it tuned "right". You must have all of these conditions satisfied simulataneously: a) SWR is close to 1:1. Don't be happy with 2:1 b) You're measuring at your intended operating frequency c) The antenna is mounted where it's going to be used d) After driving the antenna with a 100W carrier for a full 15 minute, and then touching the antenna within 20 seconds after removing power, NOTHING is warm. If you can satisfy all four criteria at once, then you're turning all your RF into radiation (point source style). This does not prove the EH concept at all, but rather is a validation experiment for any small antenna. If you send RF power to an antenna, it can only go three place - into radiation, heat or reflected back to the transmitter. So, get the latter two items down to zero, and you've got a radiator. But it's a small one, and like any other small one, it's going to be near-isotropic in performance. Best case should be 2.15dB below a free-space dipole. And a free-space dipole is about 6dB BETTER than the average back-yard dipole at 50 feet. AM Reply to a comment by : N0GV on 2002-08-30 Gee --- And I guess that you guys are all impressed with an antenna which admittedly has more than 9 dB of loss as compared with a LOW dipole. (1 1/2 S units is 9 dB). Sure it radiates less but it makes a great space heater! About the lack of EMI -- the earlier poster had it right -- no signal = no EMI. I've read the patent and the theory behind it and it presumes that the E X H = S relationship does not apply for the Poynting vector! Sorry but it just ain't so -- the direction of propagation is normal to both the E and H fields and if either one of them drops to zero then it flat does not radiate! Likewise the Z0 of free space is proportional to the ratio of E(theta) to H(Phi) and we don't even want to begin thinking of rewriting the impedance of free space by increasing the relative permeability or permittivity of free space. Hence the result is pure bunk. On the other hand it is a really interesting way to take a several thousand dollar transciever capable of 100-200 Watts and turn it into a QRP rig! Seems there was an anecdotal story of a South Dakota contact using a dummy load as a radiator in a recent QST..... Please don't believe this garbage about the EH antenna as it is really, really, specious! Grover Larkins and, yes I have a EE degree (three in fact) and, yes I did indeed learn fields and waves from Bob Collin. Reply to a comment by : KD3V on 2002-08-20 !!! LISTEN UP SKEPTICS !!! Please stop making fools of yourselves! If you haven't tried it you have NO BASIS for saying anything! We made one! I used it! it works! I am an electrical engineer. I have been one since 1982. These EH antennas in fact: 1. ... are not "getting something for nothing", 2. they are not "changing the laws of physics in order to make something better than it is", 3. they agree completely with the law of physics that tells us how to get radiation, and for those that have taken the time to read the relevant website, this is called the "Poynting Theorem". This antenna is simple a DIFFERENT method to work this "law of physics". 4. They WORK! I know because I used one! I sent the article to a friend who wanted to make one, he had a friend of his duplicate the 20 meter version that was detailed on the web site. He used it and then I put it up in place on the roof. Simply put, I worked the world on it! I live in Hollywood Calif. From John in South Africa, a 5-7 ... on the LONG path... a FM5 in Martinique, VK's ZL's ZK1, you name it and I only had it for 3 days! So! Read the web sites! These antennas are not using feedline rariation, they are genuine rariators using a different method to create the crossed EM field and as a result they do not need the "linear" distance used by a diplole! These antennas just do it DIFFERENTLY! Yea, i get upset by the "ignorant" who speak up with no basis from which to do so. In the place of facts you put baseless opinion, and in the place of knowledge you put "authority". You are all only making fools of yourselves and those of us who take the time to "find out for ourselves" are the ones who gain real knowledge! We were curious so we built one and we found that it works! Simple. We didn't know until we tried... but we also didn't try to slam it until we KNEW something about which we wanted to speak! I would have posted a few photos but you can already see them when you go read the web site referenced! Ours looked just like theirs do. We used copper plate wrapped around PVC cylinder. Total length.. just like on the website! http://www.qsl.net/w0kph/ This is the link that describes the "full network" verion that our friend built. http://www.qsl.net/w0kph/fullnet.html | ||
| IK5IIR | 2002-09-09 | |
|---|---|---|
| RE: Small EH Antenna | ||
| To Dale... hi Dale, Ok for your project. About the EH antenna I would suggest to use a 6" PVC diameter pipe (thin wall to drain water) each cylinder can be calculated 6" X 3 spacing between the two cylinder =diameter=6" You could start with simple coil+ link version as reported on the Jack Arnold W0HPH site (please go to the www.eh-antenna.com site and you will find a link to) I think you should end with a 1.5 meters long antenna. This antenna , for me, costs nothing, is fast to build, is short, and should be about 40% efficient. Later you could try the full network version but this version can be tricky. I am available to help you . Please let me know directely at sgalast@tin.it address. 73 steve IK5IIR Reply to a comment by : WB6BYU on 2002-09-09 I've been following the evolution of these antennas since its ancestor the CFA was first introduced in the pages of AntenneX (back when "page" meant a piece of paper.) I must admit, I've always been pessimistic because the articles appeared to have more claims about performance than technical information to back up those claims. However, I'm also a pragmatist, and I know that I always have more to learn, so I am willing to give them the benefit of the doubt until there is more definite data to work with. (I've made enough DX contacts running 2 watts to a dipole to know that just being able to make contacts does not give a good indication of how well an antenna performs.) It so happens that I've been planning to run some comparisons of short 80m vertical antennas. This is for a specific application, where multiple transmitters are set out for transmitter hunting. My standard antenna is a 8m wire thrown over a tree branch, fed against 3 radials each 5m long with a base loading coil. Not particularly efficient, but adequate to receive ground wave signals up to 10km away using 1 watt and a hand-held receiver (which is what they need to do.) While we have plenty of tall trees here in Oregon to support such antennas, the folks in southern California often don't. So I am trying to design some suitable antennas about 2m tall. I have a number of possible designs, including commercial mobile antennas and helical hairpins. It looks like the EH would be a likely candidate for this application, since the 80m dimensions are less than 2m long, and it appears to be vertically polarized. My plan is to set up a test range with a common set of radials for all antennas (at least, all that need them). I have access to a calibrated field strength meter, which will be placed at least one wavelength from the antennas under test. (Further if signal strength permits.) Since I have a good supply of PVC pipe and a roll of aluminum flashing on hand (plus some large diameter cardboard tubes) as well as lot of wire, it seems it would be quite practical to build a sample EH antenna and test it along with the others. This won't verify that it is operating in a new mode, but will at least give a quantative comparison with a number of other antennas. It may be a couple of months or more before I get this project finished, but I will post the results to the TowerTalk forum here on eHam when I do. And if anyone is in the vicinity of NW Oregon and wants to help or observe, they would be welcome. - Dale WB6BYU PS: if anyone has other suggestions for antenna designs that I should try at the same time, I'd be glad to consider them. The general constraints are: maximum height about 2m tall, vertically polarized, operating about 3580 kHz. It should not require much retuning when moved (though a single control adjusted for maximum output would be fine.) Ideally such an antenna would be inexpensive and easy to build, and relatively easy to transport (since the course setter may have to carry up to 5 of them at the same time - along with the transmitters.) Please let me know at wb6byu@arrl.net if you have any suggestions. Reply to a comment by : KE0VH on 2002-09-09 Yes, I posted the original article and really haven't delved into the deep technical aspects of the antenna. Honestly, I saw a design for a small antenna and made a working model. I am also building the Twin Moxon LEO satellite antenna with successs, and while understanding the basics, aren't and don't have the time to explore the deep theory. I will leave that to all of you who seem knowledgeable and have the time. The basics here for me is that it IS something to experiment with, have FUN with, and be an amateur about. Basically from the viewpoint of time and space, I don't care how the fields set up or if it is truly EH. It works, it works for me, it fits what I need, and the size is perfect for my situation, so what if it is a "fat" dipole? Long and short of it is discussion is good, although those with smart remarks and those who want to expound upon it's lack of scientific backing and who haven't tried it should not waste the computer space in my opinion. Come on folks, lets further the spirit of amateur radio and have fun. We don't have to take everything so bloody seriously, or be critical of that which you have not even tried. Like the NOCALL guy wrote, you and I are being watched, and to discourage someone from joining the hobby because of attitude is reprehensible. Lets help, lets elmer, and lets be of SERVICE to those who might be interested. Thats why I presented the article in the first place, because it was fun, it works, and it might help someone who needs a decent antenna in a bad location/no antenna zone. KE0VH | ||
| WB6BYU | 2002-09-09 | |
|---|---|---|
| RE: Small EH Antenna | ||
| I've been following the evolution of these antennas since its ancestor the CFA was first introduced in the pages of AntenneX (back when "page" meant a piece of paper.) I must admit, I've always been pessimistic because the articles appeared to have more claims about performance than technical information to back up those claims. However, I'm also a pragmatist, and I know that I always have more to learn, so I am willing to give them the benefit of the doubt until there is more definite data to work with. (I've made enough DX contacts running 2 watts to a dipole to know that just being able to make contacts does not give a good indication of how well an antenna performs.) It so happens that I've been planning to run some comparisons of short 80m vertical antennas. This is for a specific application, where multiple transmitters are set out for transmitter hunting. My standard antenna is a 8m wire thrown over a tree branch, fed against 3 radials each 5m long with a base loading coil. Not particularly efficient, but adequate to receive ground wave signals up to 10km away using 1 watt and a hand-held receiver (which is what they need to do.) While we have plenty of tall trees here in Oregon to support such antennas, the folks in southern California often don't. So I am trying to design some suitable antennas about 2m tall. I have a number of possible designs, including commercial mobile antennas and helical hairpins. It looks like the EH would be a likely candidate for this application, since the 80m dimensions are less than 2m long, and it appears to be vertically polarized. My plan is to set up a test range with a common set of radials for all antennas (at least, all that need them). I have access to a calibrated field strength meter, which will be placed at least one wavelength from the antennas under test. (Further if signal strength permits.) Since I have a good supply of PVC pipe and a roll of aluminum flashing on hand (plus some large diameter cardboard tubes) as well as lot of wire, it seems it would be quite practical to build a sample EH antenna and test it along with the others. This won't verify that it is operating in a new mode, but will at least give a quantative comparison with a number of other antennas. It may be a couple of months or more before I get this project finished, but I will post the results to the TowerTalk forum here on eHam when I do. And if anyone is in the vicinity of NW Oregon and wants to help or observe, they would be welcome. - Dale WB6BYU PS: if anyone has other suggestions for antenna designs that I should try at the same time, I'd be glad to consider them. The general constraints are: maximum height about 2m tall, vertically polarized, operating about 3580 kHz. It should not require much retuning when moved (though a single control adjusted for maximum output would be fine.) Ideally such an antenna would be inexpensive and easy to build, and relatively easy to transport (since the course setter may have to carry up to 5 of them at the same time - along with the transmitters.) Please let me know at wb6byu@arrl.net if you have any suggestions. Reply to a comment by : KE0VH on 2002-09-09 Yes, I posted the original article and really haven't delved into the deep technical aspects of the antenna. Honestly, I saw a design for a small antenna and made a working model. I am also building the Twin Moxon LEO satellite antenna with successs, and while understanding the basics, aren't and don't have the time to explore the deep theory. I will leave that to all of you who seem knowledgeable and have the time. The basics here for me is that it IS something to experiment with, have FUN with, and be an amateur about. Basically from the viewpoint of time and space, I don't care how the fields set up or if it is truly EH. It works, it works for me, it fits what I need, and the size is perfect for my situation, so what if it is a "fat" dipole? Long and short of it is discussion is good, although those with smart remarks and those who want to expound upon it's lack of scientific backing and who haven't tried it should not waste the computer space in my opinion. Come on folks, lets further the spirit of amateur radio and have fun. We don't have to take everything so bloody seriously, or be critical of that which you have not even tried. Like the NOCALL guy wrote, you and I are being watched, and to discourage someone from joining the hobby because of attitude is reprehensible. Lets help, lets elmer, and lets be of SERVICE to those who might be interested. Thats why I presented the article in the first place, because it was fun, it works, and it might help someone who needs a decent antenna in a bad location/no antenna zone. KE0VH | ||
| KE0VH | 2002-09-09 | |
|---|---|---|
| Small EH Antenna | ||
| Yes, I posted the original article and really haven't delved into the deep technical aspects of the antenna. Honestly, I saw a design for a small antenna and made a working model. I am also building the Twin Moxon LEO satellite antenna with successs, and while understanding the basics, aren't and don't have the time to explore the deep theory. I will leave that to all of you who seem knowledgeable and have the time. The basics here for me is that it IS something to experiment with, have FUN with, and be an amateur about. Basically from the viewpoint of time and space, I don't care how the fields set up or if it is truly EH. It works, it works for me, it fits what I need, and the size is perfect for my situation, so what if it is a "fat" dipole? Long and short of it is discussion is good, although those with smart remarks and those who want to expound upon it's lack of scientific backing and who haven't tried it should not waste the computer space in my opinion. Come on folks, lets further the spirit of amateur radio and have fun. We don't have to take everything so bloody seriously, or be critical of that which you have not even tried. Like the NOCALL guy wrote, you and I are being watched, and to discourage someone from joining the hobby because of attitude is reprehensible. Lets help, lets elmer, and lets be of SERVICE to those who might be interested. Thats why I presented the article in the first place, because it was fun, it works, and it might help someone who needs a decent antenna in a bad location/no antenna zone. KE0VH | ||
| K1BRF | 2002-09-09 | |
|---|---|---|
| RE: Small EH Antenna | ||
| re: K3AN comment Guess what? We manufacture those for a living and sell millions of dollars worth to the US Government (Navy) is buying them. They are called fuel cells. Now about this EH antenna thing. All that has to happen is that the arrl lab builds one, tests it and finds it is a power-losing vertical or whatever and we can get on with our lives. Until one is analyzed and the theory discussed, this is like reading a debate on UFOs, colloidal silver, endless energy, perpetual motion, cold fusion or whatever. If all these folks had spent the time building one and testing it instead of keyboarding we would have an answer by now. Reply to a comment by : K3AN on 2002-08-21 I am on the verge of achieving a radical breakthrough that will finally achieve the dream of almost limitless free power from plain old water! Since water consists of just hydrogen and oxygen, combining those elements to release the power results in no pollution. I will be prepared to demonstrate this publicly in the near future. To the invitees of that demonstration, I must ask in advance that they pay no attention to the man behind the curtain ;-) Reply to a comment by : W7KWS on 2002-08-20 I forgot, the band of reference in my last post is for 20 meters (14.2 MHz.). Reply to a comment by : W7KWS on 2002-08-20 In using wire length as a linear indicator of signal capture/radiation efficiency (presumed law of physics in previous post), how do you account for the fact that a tuned magnetic loop antenna, at 8.5 Ft. in circumference, is only down 1.0 dB below a "large antenna" for the same band? Reference the ARRL Antenna Handbook, 16th edition, page 5-13, loop design No. 5. Good wishes to all in hopes we all learn here. 73, Bob, W7KWS Reply to a comment by : W3JJH on 2002-08-20 I'm open-minded, but not so open-minded that my brain has fallen out. 1. My dummy load has a 1.1:1 SWR on 20-m. It doesn't radiate very well. 2. At 6 dB/S-unit, a drop of 1-1/2 S-units represents a 90-% power loss. If the signals coming in the side of my dipole were only 9 dB above those from a small "EH" antenna, I would start checking for loose or corroded connections on the dipole. The current in a wire in an H-field is proportional to the strength of field times the length of the wire. Use a shorter wire, get a smaller signal. The potential on a conductive surface in an E-field is proportional to the strength of the field times the size of the surface. Use a smaller area, get a smaller signal. Scotty is right: "Ye canna change the laws of physics!." | ||
| IK5IIR | 2002-09-08 | |
|---|---|---|
| RE: Small EH Antenna | ||
| Dear AM, I really appreciate your efforts and I got all your questions. Please consider I understand your thought and your professional approach. But if you look back on this topic , you will see a lot of comments from many experimenters, many practical questions/considerations. OK in the last period those mails were vanished. I have earned some experience on this matter and I think we shouldn't have too much "technical" comments here. many experimenters could be scared of this. I repeat, I understand perfectely what you are saying but I would prefere keep the discussion more practical. I think I will send to you a private email ,if I can, to go more in deep on many points. I am inviting all the experimenters to ask me about any hints and kinks to have one of it well built, for instance. I am sure there are a lot of doubts about the antenna's construction, how tune it, how install it...and so on.This forum is an excellent tool to share between us all. In fact, and is funny, I suggest to start with the EH antenna experience , having one of these beast ready on hand, working. Then is much easier run measurements , tests to understand why is working and how. anyway consider this: efficency yes the EH antenna doesn't show any warming . Checking The heating of any antenna point is a good index . hence if the antenna parts don't show any warming we should answer to the question: where the energy goes? radiated ,probabily. In the eh antenna we have the radiation resistance dependent of a phase , I think is the only antenna . I mean the RR can change in value changing the phase shift applied in the network. In the coil+link version we have a low heating on the coil because the RR remains higher than normal (lower current on the elements) producing a lower radiation Only with the perfect phase shift we will have the minimum RR producing the best radiation. Of course there must be the impedance matching too. The two L of the full network version use a #7 gauge on the wire on 7 mhz. Operating with 400 watts there is a negligible warming on those coil. The two cylinders remain completely at the ambient temp. always.There are no hot parts in the antenna. Where the energy goes? radiated. the phase ,the core of the antenna. to understand very well how this is achieved ,let us look at a simple circuit. we have to match 50 ohm at the input to 20-J 300 antenna impedance To align the two fields we should produce a phase shift equal to the shift produced by the real 20 and the imaginary -J300 + 90 degrees . For instance assume this total value is 130 degrees.... ok use a simple L circuit formed by a L and C to transform 50 to 25 ohm. ok this net will produce a -45 degrees shift. Then use a classical T network , designed to match 25 ohm to 20-J300. This design can be calculated for the shift I need ,in this case 130 degrees minus 45= 85 degrees. well, to resume I will have a L net from 50 to 25 ohm producing a -45 degrees of phase shift. Then a T network to mach 25 to 20-J300 with a -85 degrees shift.That's it. Is not complicated at all, from a single port to another single port I have achieved the target. The 130 degrees total shift , will allow to have the two fields aligned at the antenna. remember the EH antenna start at the connector, without the right network it would be a classical short dipole with poor eff. I don't want be boring, again thanks for the attention. 73's steve Ik5IIR Reply to a comment by : N0TONE on 2002-09-07 IK5IIR and my comments: >>>...I spent the last 4 years of my life on it. After so many measurements , tests, comments, long meetings at the ham clubs and so on, I would like add my poor contribute to the discussion.<<<< Excellent. Perhaps you can fill the void. So far, nobody has offered a good way to "measure" whether these antennas are actually EH-mode or not. Only comment I've ever seen is "if they are operating efficiently, then they must be EH mode." I disagree. I have a very conventional short antenna which is efficient - it's not EH at all. There MUST be a measurement technique that proves the EH theory. Without that, the concept is irrelevant. Particularly, we want to know more about your measurements. What have you measured? What test equipment do you use? I assume you measured impedance at many points, with a vector impedance device, and that you measured the E-field and H-field at close distances and at far distances, and measured the relative phases between them so that you could justify the claims about far-field happening very close to the antenna. None of the websites describes any of the test and measurement methods, and many of us really want somebody to fill that big hole. It would be extremely good if you showed photographs of your measurement setups, showing the test equipment with the results displayed on the meters or screens. >>>>1) is this a new concept? We think so.<<<<< But I ask - so what? Why should we care if it is a new concept? >>>>The traditional Hertz antennas use a current flowing on a conductor to produce a H field that in turn produce an E field.<<<< No. Hertz did not say that. Hertz' explanation involved the simultaneous creation of an E and an H field, 90 degrees apart from each other in time, orthogonal to each other in space, and orthogonal to the direction of propagation. It was Green, who later propsed that the numerical analysis of antennas could be completely carried out by ASSUMING that an H field "produced" an E field. His theory has often been debated, but we merrily use antenna software that assumes it's true. >>>In the EH antenna is the displacement current responsible of the H generation.<<<< This statement is in direct contradiction to Ampere's law. >>>>...with the EH antenna , the FAR field is bring close at the antenna , the Poynting theorem is satisfied and the electromagnetic wave travel in the medium.Yes the far field start at some inches from the antenna center.<<<< This claim can be easily validated by separate E and H field measurements using short electric and magnetic probes, which can be simply made from bits of coaxial cable. Why has nobody presented the results of these measurements on any of the web sites? A half day's work, with $10 in "new" equipment and you'd silence all the doubters. >>>>This takes some advantages on RX for instance. The antenna is sensitive at the electromagnetic wave and poor sensitive to the E and H field alone.the S/N ratio on Rx is improved by many dbs.practically on low bands is a pleasure receiving. <<<< Please point us to a website where you have stored .wav files comparing the EH versus something else on receive. >>>2)efficiency being the antenna based on the same physic laws and reaching a perfect integration of the two fields shows the same efficiency . We have a very low loss in the matching/phasing network , we can consider typically 3%. this takes to the declared efficiency of 97%. <<< Please explan the method by which you are able to measure these numbers. Engineers whose Ph.D. is in electromagnetics would never claim these numbers, even on the best aperture antennas ever made, so how can you? These are not numbers that one should be claiming, unless you can describe the method of measurement, well enough that others can duplicate it. >>>>3) The only version capable of the above efficiency is the full network version. The coil+link version may hve from 4 to 6 db of loss.<<<< That means that of 100 watts fed into it, 75 watts heats the coil. That should melt the coil described by KE0VH, made of 22 gauge wire. Does it? >>>> A simple coil can not achieve the requested phase to align perfectely the two fields. <<<< You have a one-port antenna drive. You have a one-port input to the network. You cannot derive ANY two-port network that separately adjusts the phasing of voltage and current, or can change the relative phase of them. Unless you're changing the laws of physics. >>>>4) equivalent circuit when the conditions to have the two fields aligned are satisfied , suddenly a high RR (radiation resistance) develops . This high RR was NOT there before. without the right phase shift on the network the EH antenna is just a normal short hertz antenna with poor efficiency and low RR. Well, the typical RR of a standard EH antenna is 2360 ohms. The antenna is a sort of a dipole, not need the ground at all. Now you can understand why is so efficient. The equivalent Circuit is a RC series .<<< First, this doesn't explain the efficiency. Second, these values are hard to believe. Please describe the method for measuring the numbers. If you are depending on mathematical de-embedding through the phasing network to calculate the values, present the equations. To date, I have not seen anybody successfully explain how these numbers were arrived at. What test equipment did you use? How did you calibrate it? What was the data reduction method? Please present schematics showing the probe entry points for the various measurement instruments that you used to produce these numbers. >>>there is asmall L too but it is tuned out by the capacitor . Nobody can rephase a cap hence the RR has the V and I in phase and the C has the V and I 90 degrees apart. <<< Likewise, if you have a series RC, there is a fixed, unchangeable phase relationship. Nobody can rephase it. >>>>5) the shape of the two elements (cylinders) and their proportion each other , are important to achieve the best fields integration <<<< Nothing in the propsed theory would result in this conclusion. Please provide the logical connection between theory and this result. >>>>>6) comparing a well built and well tuned EH against a vertical dipole ( or GP) must have NO differences . I read many comments about 1 Point S under...this is valid for the coil+link version . The full network version (tricky? yes a little..) shows no difference. a 14 mhz EH built using a 2" pipe support having the radiators about the 2% wavelenght, shows a bandwidth very large....about 1.5 MHZ at +-3db. (!!!) 97% of eff. almost NO noise on RX. <<<< Again, please describe the measurement equiment and method used to demonstrate 97% efficiency and 1.5 MHz bandwidth, and the 3dB. Also, what is the 3dB in reference to? Return loss? Gain? Efficiency? Something else? A dB is always relative to something else - what are your dB relative to? >>>>7) the building can be tricky. For this we decided to reveal all, no secrets.<<<< You have left a LOT of secrets. Particularly, you present many numerical values, for RR, for efficiency, and so on, but you and K0KPH have, to date, been utterly unwilling to describe how you arrived at those numbers. THAT is the secret and it is a crucial one. Physical details of dimensions and material used are utterly immaterial in comparison to knowing how you actually make your measurements. >>>> hence you can ask any help to me,<<<< I have hereby asked for help in explaining how you arrived at some of your numerical conclusions. >>>>Dear friends I wanted summarize some points...I know there are so many things to say....hi.....I am available to discuss with you about it. <<<< Excellent. I have asked some direct questions, and look forward eagerly to your direct answers. AM Reply to a comment by : IK5IIR on 2002-09-05 Hello dear friends, I am stefano (steve) IK5IIR . Kevin KE0VH told me he decided to post his famous article about the EH antennas on this forum . I carefully read all the comments and I want thank all of you to be so open minded , prepared, interested on this fascinating hobby. I am here just like an ham , loving on a total way the ham radio and the antennas on particular. I spent all my ham life homebrewing. Well this amazing new concept.....wow .... as many of you know, I spent the last 4 years of my life on it. After so many measurements , tests, comments, long meetings at the ham clubs and so on, I would like add my poor contribute to the discussion. I am just speaking as ham , I don't want on any way touch the commercial "reasons". I would like just clarify, chat, help ( if I can) have fun ..on this topic. 1) is this a new concept? We think so. The traditional Hertz antennas use a current flowing on a conductor to produce a H field that in turn produce an E field. these fields are 90 degrees apart in the space and 90 degrees apart timing.Well at 1/3 of a wavelenght (may be more ....) these fields appear to be in time phase a electromagnetic wave is generated and travel in the space. This antenna satisfy the Poynting theorem In the EH antenna is the displacement current responsible of the H generation . This is the main difference...not current in a conductor but still we have a H field and applied to two particular and funny plates of a capacitor . 90 degrees in time apart we have an E field also . These two fields are 90 degrees apart in the space also. Ok we have the same condition as above. The two fields are out of phase ....hence we added a special phasing/matching network (attention matching AND phasing) to allow the two fields alignement. doing this , with the EH antenna , the FAR field is bring close at the antenna , the Poynting theorem is satisfied and the electromagnetic wave travel in the medium.Yes the far field start at some inches from the antenna center. This takes some advantages on RX for instance. The antenna is sensitive at the electromagnetic wave and poor sensitive to the E and H field alone.the S/N ratio on Rx is improved by many dbs.practically on low bands is a pleasure receiving. as you see the two antennas ..hertz and EH work on the same principle but with different application. HENCE....new physic law? NO is wrong. same laws, different application. Of course I used a simplified message but I hope is clear enough. 2)efficiency being the antenna based on the same physic laws and reaching a perfect integration of the two fields shows the same efficiency . We have a very low loss in the matching/phasing network , we can consider typically 3%. this takes to the declared efficiency of 97%. 3) The only version capable of the above efficiency is the full network version. The coil+link version may hve from 4 to 6 db of loss. A simple coil can not achieve the requested phase to align perfectely the two fields. 4) equivalent circuit when the conditions to have the two fields aligned are satisfied , suddenly a high RR (radiation resistance) develops . This high RR was NOT there before. without the right phase shift on the network the EH antenna is just a normal short hertz antenna with poor efficiency and low RR. Well, the typical RR of a standard EH antenna is 2360 ohms. The antenna is a sort of a dipole, not need the ground at all. Now you can understand why is so efficient. The equivalent Circuit is a RC series . there is asmall L too but it is tuned out by the capacitor . Nobody can rephase a cap hence the RR has the V and I in phase and the C has the V and I 90 degrees apart. 5) the shape of the two elements (cylinders) and their proportion each other , are important to achieve the best fields integration 6) comparing a well built and well tuned EH against a vertical dipole ( or GP) must have NO differences . I read many comments about 1 Point S under...this is valid for the coil+link version . The full network version (tricky? yes a little..) shows no difference. a 14 mhz EH built using a 2" pipe support having the radiators about the 2% wavelenght, shows a bandwidth very large....about 1.5 MHZ at +-3db. (!!!) 97% of eff. almost NO noise on RX. 7) the building can be tricky. For this we decided to reveal all, no secrets. hence you can ask any help to me, I will be very happy to help everybody to have a complete success. remember the antennas must be compared at same heights and allowing some disyance each other to skip any reflections, absorbations. couplings. Since the beginning of this adventure , I read of antenna mounting ..everywhere !!! bathroom, kitchen, dining room and so on....you can not compare a dipole installed 20 meters high with an EH in the bsement inside the house. Yes the EH antenna is not sensitive to nearby objects... (remember the far field start at the antenna) BUT the signal can not be the same inside a house. Anyway I got amazing reports hamming inside !!! Be careful for body exposure at the rf. Dear friends I wanted summarize some points...I know there are so many things to say....hi.....I am available to discuss with you about it. It is my pleasure. have fun ! 73's steve IK5IIR | ||
| IK5IIR | 2002-09-08 | |
|---|---|---|
| RE: Small EH Antenna | ||
| Hi Marinos, pay attention on your eh. You must use a coil + LINK a floating link under the main coil. If you not use such device your line will be hot and easily couples with ..all....and your experiments will be bad. use a floating link under the main coil . Normally is formed by 1 or two turns of the same wire . Use the main coil to have the antenna working on the wanted F , then adjust the link to have a perfect 1:1 SWR match. Doing this procedure , please connect the SWR meter directely at the antenna's connector with NO any coax in between. When you have tuned this version , you will have 4 to 6 db of loss respect to a dipole, but your line will be isolated from the antenna. Please let me know 73's steve IK5IIR Reply to a comment by : SV9DRU on 2002-09-07 Hi to all, Since I was curious enough to build one of these antennas myself, just to try it out, I would like to add some comments to the discussion. I built a version on a tube with 6.9cm OD, ODx3.15=21.73cm cylinder length, distance between cylinders = OD, 2 turns of enameled wire (1.5mm) in series with each cylinder and about 14 turns of wire at the bottom of the structure. The antenna was resonant at the lower end of the 40m band and gave me good received signal compared to my 68ft windom mounted on my roof but ONLY when the radio ground was connected to the coax of the windom (had a common ground A-B switch with both antennas on during comparisons). So even though initially I was impressed by the results, seeing 1-2 S points higher in the EH antenna at its resonant frequency compared to the Windom, my enthusiasm faded when I realized that the good reception was totally depended on the common ground between the two antennas and could not be duplicated when connecting the EH antenna alone having the Windom disconnected. Bandwidth wise, my antenna had 1:1 SWR for more or less 200Khz depending on the number of turns in the bottom coil and the spreading of the last few turns. That got me thinking that maybe the EH antenna does work but it DOES require a good resonant counterpoise and maybe that it was using the wire antenna for that purpose. Maybe one of these days I will find some time to add a second coil and the 2 capacitors described in the original construction article by IK5IIR and see if that makes any difference in the ground requirements.... On the other hand, reading through the different comments in this post, I think that too many people are trying to go into exhausting technical details and analyses in order to prove that this antenna is not working and too few people are spending a few hours building their own just for the fun of it ! After all ham radio is about experimentation and we all must be as open minded as possible to new ideas and applications even if they do not fully "comply" to an existing theory....It is true that there is a certain degree of mind "inertia" that has to be overcome when a new idea is introduced, but we, as amateurs have to keep it to a minimum... 73, Marinos, sv9dru Reply to a comment by : N0TONE on 2002-09-07 IK5IIR and my comments: >>>...I spent the last 4 years of my life on it. After so many measurements , tests, comments, long meetings at the ham clubs and so on, I would like add my poor contribute to the discussion.<<<< Excellent. Perhaps you can fill the void. So far, nobody has offered a good way to "measure" whether these antennas are actually EH-mode or not. Only comment I've ever seen is "if they are operating efficiently, then they must be EH mode." I disagree. I have a very conventional short antenna which is efficient - it's not EH at all. There MUST be a measurement technique that proves the EH theory. Without that, the concept is irrelevant. Particularly, we want to know more about your measurements. What have you measured? What test equipment do you use? I assume you measured impedance at many points, with a vector impedance device, and that you measured the E-field and H-field at close distances and at far distances, and measured the relative phases between them so that you could justify the claims about far-field happening very close to the antenna. None of the websites describes any of the test and measurement methods, and many of us really want somebody to fill that big hole. It would be extremely good if you showed photographs of your measurement setups, showing the test equipment with the results displayed on the meters or screens. >>>>1) is this a new concept? We think so.<<<<< But I ask - so what? Why should we care if it is a new concept? >>>>The traditional Hertz antennas use a current flowing on a conductor to produce a H field that in turn produce an E field.<<<< No. Hertz did not say that. Hertz' explanation involved the simultaneous creation of an E and an H field, 90 degrees apart from each other in time, orthogonal to each other in space, and orthogonal to the direction of propagation. It was Green, who later propsed that the numerical analysis of antennas could be completely carried out by ASSUMING that an H field "produced" an E field. His theory has often been debated, but we merrily use antenna software that assumes it's true. >>>In the EH antenna is the displacement current responsible of the H generation.<<<< This statement is in direct contradiction to Ampere's law. >>>>...with the EH antenna , the FAR field is bring close at the antenna , the Poynting theorem is satisfied and the electromagnetic wave travel in the medium.Yes the far field start at some inches from the antenna center.<<<< This claim can be easily validated by separate E and H field measurements using short electric and magnetic probes, which can be simply made from bits of coaxial cable. Why has nobody presented the results of these measurements on any of the web sites? A half day's work, with $10 in "new" equipment and you'd silence all the doubters. >>>>This takes some advantages on RX for instance. The antenna is sensitive at the electromagnetic wave and poor sensitive to the E and H field alone.the S/N ratio on Rx is improved by many dbs.practically on low bands is a pleasure receiving. <<<< Please point us to a website where you have stored .wav files comparing the EH versus something else on receive. >>>2)efficiency being the antenna based on the same physic laws and reaching a perfect integration of the two fields shows the same efficiency . We have a very low loss in the matching/phasing network , we can consider typically 3%. this takes to the declared efficiency of 97%. <<< Please explan the method by which you are able to measure these numbers. Engineers whose Ph.D. is in electromagnetics would never claim these numbers, even on the best aperture antennas ever made, so how can you? These are not numbers that one should be claiming, unless you can describe the method of measurement, well enough that others can duplicate it. >>>>3) The only version capable of the above efficiency is the full network version. The coil+link version may hve from 4 to 6 db of loss.<<<< That means that of 100 watts fed into it, 75 watts heats the coil. That should melt the coil described by KE0VH, made of 22 gauge wire. Does it? >>>> A simple coil can not achieve the requested phase to align perfectely the two fields. <<<< You have a one-port antenna drive. You have a one-port input to the network. You cannot derive ANY two-port network that separately adjusts the phasing of voltage and current, or can change the relative phase of them. Unless you're changing the laws of physics. >>>>4) equivalent circuit when the conditions to have the two fields aligned are satisfied , suddenly a high RR (radiation resistance) develops . This high RR was NOT there before. without the right phase shift on the network the EH antenna is just a normal short hertz antenna with poor efficiency and low RR. Well, the typical RR of a standard EH antenna is 2360 ohms. The antenna is a sort of a dipole, not need the ground at all. Now you can understand why is so efficient. The equivalent Circuit is a RC series .<<< First, this doesn't explain the efficiency. Second, these values are hard to believe. Please describe the method for measuring the numbers. If you are depending on mathematical de-embedding through the phasing network to calculate the values, present the equations. To date, I have not seen anybody successfully explain how these numbers were arrived at. What test equipment did you use? How did you calibrate it? What was the data reduction method? Please present schematics showing the probe entry points for the various measurement instruments that you used to produce these numbers. >>>there is asmall L too but it is tuned out by the capacitor . Nobody can rephase a cap hence the RR has the V and I in phase and the C has the V and I 90 degrees apart. <<< Likewise, if you have a series RC, there is a fixed, unchangeable phase relationship. Nobody can rephase it. >>>>5) the shape of the two elements (cylinders) and their proportion each other , are important to achieve the best fields integration <<<< Nothing in the propsed theory would result in this conclusion. Please provide the logical connection between theory and this result. >>>>>6) comparing a well built and well tuned EH against a vertical dipole ( or GP) must have NO differences . I read many comments about 1 Point S under...this is valid for the coil+link version . The full network version (tricky? yes a little..) shows no difference. a 14 mhz EH built using a 2" pipe support having the radiators about the 2% wavelenght, shows a bandwidth very large....about 1.5 MHZ at +-3db. (!!!) 97% of eff. almost NO noise on RX. <<<< Again, please describe the measurement equiment and method used to demonstrate 97% efficiency and 1.5 MHz bandwidth, and the 3dB. Also, what is the 3dB in reference to? Return loss? Gain? Efficiency? Something else? A dB is always relative to something else - what are your dB relative to? >>>>7) the building can be tricky. For this we decided to reveal all, no secrets.<<<< You have left a LOT of secrets. Particularly, you present many numerical values, for RR, for efficiency, and so on, but you and K0KPH have, to date, been utterly unwilling to describe how you arrived at those numbers. THAT is the secret and it is a crucial one. Physical details of dimensions and material used are utterly immaterial in comparison to knowing how you actually make your measurements. >>>> hence you can ask any help to me,<<<< I have hereby asked for help in explaining how you arrived at some of your numerical conclusions. >>>>Dear friends I wanted summarize some points...I know there are so many things to say....hi.....I am available to discuss with you about it. <<<< Excellent. I have asked some direct questions, and look forward eagerly to your direct answers. AM Reply to a comment by : IK5IIR on 2002-09-05 Hello dear friends, I am stefano (steve) IK5IIR . Kevin KE0VH told me he decided to post his famous article about the EH antennas on this forum . I carefully read all the comments and I want thank all of you to be so open minded , prepared, interested on this fascinating hobby. I am here just like an ham , loving on a total way the ham radio and the antennas on particular. I spent all my ham life homebrewing. Well this amazing new concept.....wow .... as many of you know, I spent the last 4 years of my life on it. After so many measurements , tests, comments, long meetings at the ham clubs and so on, I would like add my poor contribute to the discussion. I am just speaking as ham , I don't want on any way touch the commercial "reasons". I would like just clarify, chat, help ( if I can) have fun ..on this topic. 1) is this a new concept? We think so. The traditional Hertz antennas use a current flowing on a conductor to produce a H field that in turn produce an E field. these fields are 90 degrees apart in the space and 90 degrees apart timing.Well at 1/3 of a wavelenght (may be more ....) these fields appear to be in time phase a electromagnetic wave is generated and travel in the space. This antenna satisfy the Poynting theorem In the EH antenna is the displacement current responsible of the H generation . This is the main difference...not current in a conductor but still we have a H field and applied to two particular and funny plates of a capacitor . 90 degrees in time apart we have an E field also . These two fields are 90 degrees apart in the space also. Ok we have the same condition as above. The two fields are out of phase ....hence we added a special phasing/matching network (attention matching AND phasing) to allow the two fields alignement. doing this , with the EH antenna , the FAR field is bring close at the antenna , the Poynting theorem is satisfied and the electromagnetic wave travel in the medium.Yes the far field start at some inches from the antenna center. This takes some advantages on RX for instance. The antenna is sensitive at the electromagnetic wave and poor sensitive to the E and H field alone.the S/N ratio on Rx is improved by many dbs.practically on low bands is a pleasure receiving. as you see the two antennas ..hertz and EH work on the same principle but with different application. HENCE....new physic law? NO is wrong. same laws, different application. Of course I used a simplified message but I hope is clear enough. 2)efficiency being the antenna based on the same physic laws and reaching a perfect integration of the two fields shows the same efficiency . We have a very low loss in the matching/phasing network , we can consider typically 3%. this takes to the declared efficiency of 97%. 3) The only version capable of the above efficiency is the full network version. The coil+link version may hve from 4 to 6 db of loss. A simple coil can not achieve the requested phase to align perfectely the two fields. 4) equivalent circuit when the conditions to have the two fields aligned are satisfied , suddenly a high RR (radiation resistance) develops . This high RR was NOT there before. without the right phase shift on the network the EH antenna is just a normal short hertz antenna with poor efficiency and low RR. Well, the typical RR of a standard EH antenna is 2360 ohms. The antenna is a sort of a dipole, not need the ground at all. Now you can understand why is so efficient. The equivalent Circuit is a RC series . there is asmall L too but it is tuned out by the capacitor . Nobody can rephase a cap hence the RR has the V and I in phase and the C has the V and I 90 degrees apart. 5) the shape of the two elements (cylinders) and their proportion each other , are important to achieve the best fields integration 6) comparing a well built and well tuned EH against a vertical dipole ( or GP) must have NO differences . I read many comments about 1 Point S under...this is valid for the coil+link version . The full network version (tricky? yes a little..) shows no difference. a 14 mhz EH built using a 2" pipe support having the radiators about the 2% wavelenght, shows a bandwidth very large....about 1.5 MHZ at +-3db. (!!!) 97% of eff. almost NO noise on RX. 7) the building can be tricky. For this we decided to reveal all, no secrets. hence you can ask any help to me, I will be very happy to help everybody to have a complete success. remember the antennas must be compared at same heights and allowing some disyance each other to skip any reflections, absorbations. couplings. Since the beginning of this adventure , I read of antenna mounting ..everywhere !!! bathroom, kitchen, dining room and so on....you can not compare a dipole installed 20 meters high with an EH in the bsement inside the house. Yes the EH antenna is not sensitive to nearby objects... (remember the far field start at the antenna) BUT the signal can not be the same inside a house. Anyway I got amazing reports hamming inside !!! Be careful for body exposure at the rf. Dear friends I wanted summarize some points...I know there are so many things to say....hi.....I am available to discuss with you about it. It is my pleasure. have fun ! 73's steve IK5IIR | ||
| N0TONE | 2002-09-08 | |
|---|---|---|
| RE: Small EH Antenna | ||
| >>>On the other hand, reading through the different comments in this post, I think that too many people are trying to go into exhausting technical details and analyses in order to prove that this antenna is not working and too few people are spending a few hours building their own just for the fun of it ! After all ham radio is about experimentation and we all must be as open minded as possible to new ideas and applications even if they do not fully "comply" to an existing theory....It is true that there is a certain degree of mind "inertia" that has to be overcome when a new idea is introduced, but we, as amateurs have to keep it to a minimum... <<< Marianos, most of us who are going into "exhausting technical details and analyses" are not doing so to prove that the antenna does not work. Instead, we are trying to demonstrate by what method it DOES work. I assume that it works. Why is it important to know HOW it works? You have presented a perfect example. You have built the antenna, and it does not seem to work unless it is somehow associated with your windom. If you really understood how this antenna is supposed to work, then you would very quickly be able to make a few simple measurements to determine where the power is going, and fix the problem. It is precisely because we do not know enough details that things happen such as to you - where you're left grasping for straws as to why it didn't work for you and how to fix the problem. I'll try to separate some things here. The original article had a couple of main points. 1) An antenna has been invented that operates using a "new" mode, which they call EH. In the article here by KE0VH, the article on QRZ.COM by KE0VH and the websites by IK5IIR, W5QJR and W0KPH, they write an exhausting amount about the fact that this antenna operates on a "new" principle. Since this seems to be a very important fact to the article and website writers, it is definitely worth investigating. The fact that it works on this "EH" principal is used as an excuse to claim that those of us who are knowledgeable in electromagnetics will never be able to measure the fields around the antenna accurately. Despite the fact that many of us thing we have done exactly that. Frankly, I don't care if it's a new mode or not, as long as the developers would give us enough details of how they came up with their numerical claims (driving impedance "suddenly" rises when you achieve EH mode, efficiency is 97%, etc - these values come from measurements, and we should know how they made the measurements and with what equiment). 2) A construction method has been presented that allows any amateur to easily construct a small, yet efficient, antenna. This is good news. This claim is being debated by some, but not by me. This is the "easily understood" part of the article. It is the only important part of the article for some, such as yourself. However, if part 1 is not cleared up, there are going to be a lot of hams who duplicate the antenna right down to the millimeter, who cannot get it to work, and are at a complete loss as to why, because the creators have failed to provide us with a useful method for measuring what's really happening with the antenna. So, whether we're going into too many exhausting technical details or not depends on whether you're satisfied with having an antenna that does not work, and utterly no explanation of why. Those of us who experiment with antennas and hone and refine them know that it's not adequate to simply build one and have it work. You must be able to build it, and successfully predict what performance difference you will get if you change some small aspect of it. By the way, did you try transmitting 100 watts CW into it, key-down, and look for things that are getting warm? That would clue you in to where the losses are, although it probably won't help solve the problem. 73, AM Reply to a comment by : SV9DRU on 2002-09-07 Hi to all, Since I was curious enough to build one of these antennas myself, just to try it out, I would like to add some comments to the discussion. I built a version on a tube with 6.9cm OD, ODx3.15=21.73cm cylinder length, distance between cylinders = OD, 2 turns of enameled wire (1.5mm) in series with each cylinder and about 14 turns of wire at the bottom of the structure. The antenna was resonant at the lower end of the 40m band and gave me good received signal compared to my 68ft windom mounted on my roof but ONLY when the radio ground was connected to the coax of the windom (had a common ground A-B switch with both antennas on during comparisons). So even though initially I was impressed by the results, seeing 1-2 S points higher in the EH antenna at its resonant frequency compared to the Windom, my enthusiasm faded when I realized that the good reception was totally depended on the common ground between the two antennas and could not be duplicated when connecting the EH antenna alone having the Windom disconnected. Bandwidth wise, my antenna had 1:1 SWR for more or less 200Khz depending on the number of turns in the bottom coil and the spreading of the last few turns. That got me thinking that maybe the EH antenna does work but it DOES require a good resonant counterpoise and maybe that it was using the wire antenna for that purpose. Maybe one of these days I will find some time to add a second coil and the 2 capacitors described in the original construction article by IK5IIR and see if that makes any difference in the ground requirements.... On the other hand, reading through the different comments in this post, I think that too many people are trying to go into exhausting technical details and analyses in order to prove that this antenna is not working and too few people are spending a few hours building their own just for the fun of it ! After all ham radio is about experimentation and we all must be as open minded as possible to new ideas and applications even if they do not fully "comply" to an existing theory....It is true that there is a certain degree of mind "inertia" that has to be overcome when a new idea is introduced, but we, as amateurs have to keep it to a minimum... 73, Marinos, sv9dru Reply to a comment by : N0TONE on 2002-09-07 IK5IIR and my comments: >>>...I spent the last 4 years of my life on it. After so many measurements , tests, comments, long meetings at the ham clubs and so on, I would like add my poor contribute to the discussion.<<<< Excellent. Perhaps you can fill the void. So far, nobody has offered a good way to "measure" whether these antennas are actually EH-mode or not. Only comment I've ever seen is "if they are operating efficiently, then they must be EH mode." I disagree. I have a very conventional short antenna which is efficient - it's not EH at all. There MUST be a measurement technique that proves the EH theory. Without that, the concept is irrelevant. Particularly, we want to know more about your measurements. What have you measured? What test equipment do you use? I assume you measured impedance at many points, with a vector impedance device, and that you measured the E-field and H-field at close distances and at far distances, and measured the relative phases between them so that you could justify the claims about far-field happening very close to the antenna. None of the websites describes any of the test and measurement methods, and many of us really want somebody to fill that big hole. It would be extremely good if you showed photographs of your measurement setups, showing the test equipment with the results displayed on the meters or screens. >>>>1) is this a new concept? We think so.<<<<< But I ask - so what? Why should we care if it is a new concept? >>>>The traditional Hertz antennas use a current flowing on a conductor to produce a H field that in turn produce an E field.<<<< No. Hertz did not say that. Hertz' explanation involved the simultaneous creation of an E and an H field, 90 degrees apart from each other in time, orthogonal to each other in space, and orthogonal to the direction of propagation. It was Green, who later propsed that the numerical analysis of antennas could be completely carried out by ASSUMING that an H field "produced" an E field. His theory has often been debated, but we merrily use antenna software that assumes it's true. >>>In the EH antenna is the displacement current responsible of the H generation.<<<< This statement is in direct contradiction to Ampere's law. >>>>...with the EH antenna , the FAR field is bring close at the antenna , the Poynting theorem is satisfied and the electromagnetic wave travel in the medium.Yes the far field start at some inches from the antenna center.<<<< This claim can be easily validated by separate E and H field measurements using short electric and magnetic probes, which can be simply made from bits of coaxial cable. Why has nobody presented the results of these measurements on any of the web sites? A half day's work, with $10 in "new" equipment and you'd silence all the doubters. >>>>This takes some advantages on RX for instance. The antenna is sensitive at the electromagnetic wave and poor sensitive to the E and H field alone.the S/N ratio on Rx is improved by many dbs.practically on low bands is a pleasure receiving. <<<< Please point us to a website where you have stored .wav files comparing the EH versus something else on receive. >>>2)efficiency being the antenna based on the same physic laws and reaching a perfect integration of the two fields shows the same efficiency . We have a very low loss in the matching/phasing network , we can consider typically 3%. this takes to the declared efficiency of 97%. <<< Please explan the method by which you are able to measure these numbers. Engineers whose Ph.D. is in electromagnetics would never claim these numbers, even on the best aperture antennas ever made, so how can you? These are not numbers that one should be claiming, unless you can describe the method of measurement, well enough that others can duplicate it. >>>>3) The only version capable of the above efficiency is the full network version. The coil+link version may hve from 4 to 6 db of loss.<<<< That means that of 100 watts fed into it, 75 watts heats the coil. That should melt the coil described by KE0VH, made of 22 gauge wire. Does it? >>>> A simple coil can not achieve the requested phase to align perfectely the two fields. <<<< You have a one-port antenna drive. You have a one-port input to the network. You cannot derive ANY two-port network that separately adjusts the phasing of voltage and current, or can change the relative phase of them. Unless you're changing the laws of physics. >>>>4) equivalent circuit when the conditions to have the two fields aligned are satisfied , suddenly a high RR (radiation resistance) develops . This high RR was NOT there before. without the right phase shift on the network the EH antenna is just a normal short hertz antenna with poor efficiency and low RR. Well, the typical RR of a standard EH antenna is 2360 ohms. The antenna is a sort of a dipole, not need the ground at all. Now you can understand why is so efficient. The equivalent Circuit is a RC series .<<< First, this doesn't explain the efficiency. Second, these values are hard to believe. Please describe the method for measuring the numbers. If you are depending on mathematical de-embedding through the phasing network to calculate the values, present the equations. To date, I have not seen anybody successfully explain how these numbers were arrived at. What test equipment did you use? How did you calibrate it? What was the data reduction method? Please present schematics showing the probe entry points for the various measurement instruments that you used to produce these numbers. >>>there is asmall L too but it is tuned out by the capacitor . Nobody can rephase a cap hence the RR has the V and I in phase and the C has the V and I 90 degrees apart. <<< Likewise, if you have a series RC, there is a fixed, unchangeable phase relationship. Nobody can rephase it. >>>>5) the shape of the two elements (cylinders) and their proportion each other , are important to achieve the best fields integration <<<< Nothing in the propsed theory would result in this conclusion. Please provide the logical connection between theory and this result. >>>>>6) comparing a well built and well tuned EH against a vertical dipole ( or GP) must have NO differences . I read many comments about 1 Point S under...this is valid for the coil+link version . The full network version (tricky? yes a little..) shows no difference. a 14 mhz EH built using a 2" pipe support having the radiators about the 2% wavelenght, shows a bandwidth very large....about 1.5 MHZ at +-3db. (!!!) 97% of eff. almost NO noise on RX. <<<< Again, please describe the measurement equiment and method used to demonstrate 97% efficiency and 1.5 MHz bandwidth, and the 3dB. Also, what is the 3dB in reference to? Return loss? Gain? Efficiency? Something else? A dB is always relative to something else - what are your dB relative to? >>>>7) the building can be tricky. For this we decided to reveal all, no secrets.<<<< You have left a LOT of secrets. Particularly, you present many numerical values, for RR, for efficiency, and so on, but you and K0KPH have, to date, been utterly unwilling to describe how you arrived at those numbers. THAT is the secret and it is a crucial one. Physical details of dimensions and material used are utterly immaterial in comparison to knowing how you actually make your measurements. >>>> hence you can ask any help to me,<<<< I have hereby asked for help in explaining how you arrived at some of your numerical conclusions. >>>>Dear friends I wanted summarize some points...I know there are so many things to say....hi.....I am available to discuss with you about it. <<<< Excellent. I have asked some direct questions, and look forward eagerly to your direct answers. AM Reply to a comment by : IK5IIR on 2002-09-05 Hello dear friends, I am stefano (steve) IK5IIR . Kevin KE0VH told me he decided to post his famous article about the EH antennas on this forum . I carefully read all the comments and I want thank all of you to be so open minded , prepared, interested on this fascinating hobby. I am here just like an ham , loving on a total way the ham radio and the antennas on particular. I spent all my ham life homebrewing. Well this amazing new concept.....wow .... as many of you know, I spent the last 4 years of my life on it. After so many measurements , tests, comments, long meetings at the ham clubs and so on, I would like add my poor contribute to the discussion. I am just speaking as ham , I don't want on any way touch the commercial "reasons". I would like just clarify, chat, help ( if I can) have fun ..on this topic. 1) is this a new concept? We think so. The traditional Hertz antennas use a current flowing on a conductor to produce a H field that in turn produce an E field. these fields are 90 degrees apart in the space and 90 degrees apart timing.Well at 1/3 of a wavelenght (may be more ....) these fields appear to be in time phase a electromagnetic wave is generated and travel in the space. This antenna satisfy the Poynting theorem In the EH antenna is the displacement current responsible of the H generation . This is the main difference...not current in a conductor but still we have a H field and applied to two particular and funny plates of a capacitor . 90 degrees in time apart we have an E field also . These two fields are 90 degrees apart in the space also. Ok we have the same condition as above. The two fields are out of phase ....hence we added a special phasing/matching network (attention matching AND phasing) to allow the two fields alignement. doing this , with the EH antenna , the FAR field is bring close at the antenna , the Poynting theorem is satisfied and the electromagnetic wave travel in the medium.Yes the far field start at some inches from the antenna center. This takes some advantages on RX for instance. The antenna is sensitive at the electromagnetic wave and poor sensitive to the E and H field alone.the S/N ratio on Rx is improved by many dbs.practically on low bands is a pleasure receiving. as you see the two antennas ..hertz and EH work on the same principle but with different application. HENCE....new physic law? NO is wrong. same laws, different application. Of course I used a simplified message but I hope is clear enough. 2)efficiency being the antenna based on the same physic laws and reaching a perfect integration of the two fields shows the same efficiency . We have a very low loss in the matching/phasing network , we can consider typically 3%. this takes to the declared efficiency of 97%. 3) The only version capable of the above efficiency is the full network version. The coil+link version may hve from 4 to 6 db of loss. A simple coil can not achieve the requested phase to align perfectely the two fields. 4) equivalent circuit when the conditions to have the two fields aligned are satisfied , suddenly a high RR (radiation resistance) develops . This high RR was NOT there before. without the right phase shift on the network the EH antenna is just a normal short hertz antenna with poor efficiency and low RR. Well, the typical RR of a standard EH antenna is 2360 ohms. The antenna is a sort of a dipole, not need the ground at all. Now you can understand why is so efficient. The equivalent Circuit is a RC series . there is asmall L too but it is tuned out by the capacitor . Nobody can rephase a cap hence the RR has the V and I in phase and the C has the V and I 90 degrees apart. 5) the shape of the two elements (cylinders) and their proportion each other , are important to achieve the best fields integration 6) comparing a well built and well tuned EH against a vertical dipole ( or GP) must have NO differences . I read many comments about 1 Point S under...this is valid for the coil+link version . The full network version (tricky? yes a little..) shows no difference. a 14 mhz EH built using a 2" pipe support having the radiators about the 2% wavelenght, shows a bandwidth very large....about 1.5 MHZ at +-3db. (!!!) 97% of eff. almost NO noise on RX. 7) the building can be tricky. For this we decided to reveal all, no secrets. hence you can ask any help to me, I will be very happy to help everybody to have a complete success. remember the antennas must be compared at same heights and allowing some disyance each other to skip any reflections, absorbations. couplings. Since the beginning of this adventure , I read of antenna mounting ..everywhere !!! bathroom, kitchen, dining room and so on....you can not compare a dipole installed 20 meters high with an EH in the bsement inside the house. Yes the EH antenna is not sensitive to nearby objects... (remember the far field start at the antenna) BUT the signal can not be the same inside a house. Anyway I got amazing reports hamming inside !!! Be careful for body exposure at the rf. Dear friends I wanted summarize some points...I know there are so many things to say....hi.....I am available to discuss with you about it. It is my pleasure. have fun ! 73's steve IK5IIR | ||
| SV9DRU | 2002-09-07 | |
|---|---|---|
| RE: Small EH Antenna | ||
| Hi to all, Since I was curious enough to build one of these antennas myself, just to try it out, I would like to add some comments to the discussion. I built a version on a tube with 6.9cm OD, ODx3.15=21.73cm cylinder length, distance between cylinders = OD, 2 turns of enameled wire (1.5mm) in series with each cylinder and about 14 turns of wire at the bottom of the structure. The antenna was resonant at the lower end of the 40m band and gave me good received signal compared to my 68ft windom mounted on my roof but ONLY when the radio ground was connected to the coax of the windom (had a common ground A-B switch with both antennas on during comparisons). So even though initially I was impressed by the results, seeing 1-2 S points higher in the EH antenna at its resonant frequency compared to the Windom, my enthusiasm faded when I realized that the good reception was totally depended on the common ground between the two antennas and could not be duplicated when connecting the EH antenna alone having the Windom disconnected. Bandwidth wise, my antenna had 1:1 SWR for more or less 200Khz depending on the number of turns in the bottom coil and the spreading of the last few turns. That got me thinking that maybe the EH antenna does work but it DOES require a good resonant counterpoise and maybe that it was using the wire antenna for that purpose. Maybe one of these days I will find some time to add a second coil and the 2 capacitors described in the original construction article by IK5IIR and see if that makes any difference in the ground requirements.... On the other hand, reading through the different comments in this post, I think that too many people are trying to go into exhausting technical details and analyses in order to prove that this antenna is not working and too few people are spending a few hours building their own just for the fun of it ! After all ham radio is about experimentation and we all must be as open minded as possible to new ideas and applications even if they do not fully "comply" to an existing theory....It is true that there is a certain degree of mind "inertia" that has to be overcome when a new idea is introduced, but we, as amateurs have to keep it to a minimum... 73, Marinos, sv9dru Reply to a comment by : N0TONE on 2002-09-07 IK5IIR and my comments: >>>...I spent the last 4 years of my life on it. After so many measurements , tests, comments, long meetings at the ham clubs and so on, I would like add my poor contribute to the discussion.<<<< Excellent. Perhaps you can fill the void. So far, nobody has offered a good way to "measure" whether these antennas are actually EH-mode or not. Only comment I've ever seen is "if they are operating efficiently, then they must be EH mode." I disagree. I have a very conventional short antenna which is efficient - it's not EH at all. There MUST be a measurement technique that proves the EH theory. Without that, the concept is irrelevant. Particularly, we want to know more about your measurements. What have you measured? What test equipment do you use? I assume you measured impedance at many points, with a vector impedance device, and that you measured the E-field and H-field at close distances and at far distances, and measured the relative phases between them so that you could justify the claims about far-field happening very close to the antenna. None of the websites describes any of the test and measurement methods, and many of us really want somebody to fill that big hole. It would be extremely good if you showed photographs of your measurement setups, showing the test equipment with the results displayed on the meters or screens. >>>>1) is this a new concept? We think so.<<<<< But I ask - so what? Why should we care if it is a new concept? >>>>The traditional Hertz antennas use a current flowing on a conductor to produce a H field that in turn produce an E field.<<<< No. Hertz did not say that. Hertz' explanation involved the simultaneous creation of an E and an H field, 90 degrees apart from each other in time, orthogonal to each other in space, and orthogonal to the direction of propagation. It was Green, who later propsed that the numerical analysis of antennas could be completely carried out by ASSUMING that an H field "produced" an E field. His theory has often been debated, but we merrily use antenna software that assumes it's true. >>>In the EH antenna is the displacement current responsible of the H generation.<<<< This statement is in direct contradiction to Ampere's law. >>>>...with the EH antenna , the FAR field is bring close at the antenna , the Poynting theorem is satisfied and the electromagnetic wave travel in the medium.Yes the far field start at some inches from the antenna center.<<<< This claim can be easily validated by separate E and H field measurements using short electric and magnetic probes, which can be simply made from bits of coaxial cable. Why has nobody presented the results of these measurements on any of the web sites? A half day's work, with $10 in "new" equipment and you'd silence all the doubters. >>>>This takes some advantages on RX for instance. The antenna is sensitive at the electromagnetic wave and poor sensitive to the E and H field alone.the S/N ratio on Rx is improved by many dbs.practically on low bands is a pleasure receiving. <<<< Please point us to a website where you have stored .wav files comparing the EH versus something else on receive. >>>2)efficiency being the antenna based on the same physic laws and reaching a perfect integration of the two fields shows the same efficiency . We have a very low loss in the matching/phasing network , we can consider typically 3%. this takes to the declared efficiency of 97%. <<< Please explan the method by which you are able to measure these numbers. Engineers whose Ph.D. is in electromagnetics would never claim these numbers, even on the best aperture antennas ever made, so how can you? These are not numbers that one should be claiming, unless you can describe the method of measurement, well enough that others can duplicate it. >>>>3) The only version capable of the above efficiency is the full network version. The coil+link version may hve from 4 to 6 db of loss.<<<< That means that of 100 watts fed into it, 75 watts heats the coil. That should melt the coil described by KE0VH, made of 22 gauge wire. Does it? >>>> A simple coil can not achieve the requested phase to align perfectely the two fields. <<<< You have a one-port antenna drive. You have a one-port input to the network. You cannot derive ANY two-port network that separately adjusts the phasing of voltage and current, or can change the relative phase of them. Unless you're changing the laws of physics. >>>>4) equivalent circuit when the conditions to have the two fields aligned are satisfied , suddenly a high RR (radiation resistance) develops . This high RR was NOT there before. without the right phase shift on the network the EH antenna is just a normal short hertz antenna with poor efficiency and low RR. Well, the typical RR of a standard EH antenna is 2360 ohms. The antenna is a sort of a dipole, not need the ground at all. Now you can understand why is so efficient. The equivalent Circuit is a RC series .<<< First, this doesn't explain the efficiency. Second, these values are hard to believe. Please describe the method for measuring the numbers. If you are depending on mathematical de-embedding through the phasing network to calculate the values, present the equations. To date, I have not seen anybody successfully explain how these numbers were arrived at. What test equipment did you use? How did you calibrate it? What was the data reduction method? Please present schematics showing the probe entry points for the various measurement instruments that you used to produce these numbers. >>>there is asmall L too but it is tuned out by the capacitor . Nobody can rephase a cap hence the RR has the V and I in phase and the C has the V and I 90 degrees apart. <<< Likewise, if you have a series RC, there is a fixed, unchangeable phase relationship. Nobody can rephase it. >>>>5) the shape of the two elements (cylinders) and their proportion each other , are important to achieve the best fields integration <<<< Nothing in the propsed theory would result in this conclusion. Please provide the logical connection between theory and this result. >>>>>6) comparing a well built and well tuned EH against a vertical dipole ( or GP) must have NO differences . I read many comments about 1 Point S under...this is valid for the coil+link version . The full network version (tricky? yes a little..) shows no difference. a 14 mhz EH built using a 2" pipe support having the radiators about the 2% wavelenght, shows a bandwidth very large....about 1.5 MHZ at +-3db. (!!!) 97% of eff. almost NO noise on RX. <<<< Again, please describe the measurement equiment and method used to demonstrate 97% efficiency and 1.5 MHz bandwidth, and the 3dB. Also, what is the 3dB in reference to? Return loss? Gain? Efficiency? Something else? A dB is always relative to something else - what are your dB relative to? >>>>7) the building can be tricky. For this we decided to reveal all, no secrets.<<<< You have left a LOT of secrets. Particularly, you present many numerical values, for RR, for efficiency, and so on, but you and K0KPH have, to date, been utterly unwilling to describe how you arrived at those numbers. THAT is the secret and it is a crucial one. Physical details of dimensions and material used are utterly immaterial in comparison to knowing how you actually make your measurements. >>>> hence you can ask any help to me,<<<< I have hereby asked for help in explaining how you arrived at some of your numerical conclusions. >>>>Dear friends I wanted summarize some points...I know there are so many things to say....hi.....I am available to discuss with you about it. <<<< Excellent. I have asked some direct questions, and look forward eagerly to your direct answers. AM Reply to a comment by : IK5IIR on 2002-09-05 Hello dear friends, I am stefano (steve) IK5IIR . Kevin KE0VH told me he decided to post his famous article about the EH antennas on this forum . I carefully read all the comments and I want thank all of you to be so open minded , prepared, interested on this fascinating hobby. I am here just like an ham , loving on a total way the ham radio and the antennas on particular. I spent all my ham life homebrewing. Well this amazing new concept.....wow .... as many of you know, I spent the last 4 years of my life on it. After so many measurements , tests, comments, long meetings at the ham clubs and so on, I would like add my poor contribute to the discussion. I am just speaking as ham , I don't want on any way touch the commercial "reasons". I would like just clarify, chat, help ( if I can) have fun ..on this topic. 1) is this a new concept? We think so. The traditional Hertz antennas use a current flowing on a conductor to produce a H field that in turn produce an E field. these fields are 90 degrees apart in the space and 90 degrees apart timing.Well at 1/3 of a wavelenght (may be more ....) these fields appear to be in time phase a electromagnetic wave is generated and travel in the space. This antenna satisfy the Poynting theorem In the EH antenna is the displacement current responsible of the H generation . This is the main difference...not current in a conductor but still we have a H field and applied to two particular and funny plates of a capacitor . 90 degrees in time apart we have an E field also . These two fields are 90 degrees apart in the space also. Ok we have the same condition as above. The two fields are out of phase ....hence we added a special phasing/matching network (attention matching AND phasing) to allow the two fields alignement. doing this , with the EH antenna , the FAR field is bring close at the antenna , the Poynting theorem is satisfied and the electromagnetic wave travel in the medium.Yes the far field start at some inches from the antenna center. This takes some advantages on RX for instance. The antenna is sensitive at the electromagnetic wave and poor sensitive to the E and H field alone.the S/N ratio on Rx is improved by many dbs.practically on low bands is a pleasure receiving. as you see the two antennas ..hertz and EH work on the same principle but with different application. HENCE....new physic law? NO is wrong. same laws, different application. Of course I used a simplified message but I hope is clear enough. 2)efficiency being the antenna based on the same physic laws and reaching a perfect integration of the two fields shows the same efficiency . We have a very low loss in the matching/phasing network , we can consider typically 3%. this takes to the declared efficiency of 97%. 3) The only version capable of the above efficiency is the full network version. The coil+link version may hve from 4 to 6 db of loss. A simple coil can not achieve the requested phase to align perfectely the two fields. 4) equivalent circuit when the conditions to have the two fields aligned are satisfied , suddenly a high RR (radiation resistance) develops . This high RR was NOT there before. without the right phase shift on the network the EH antenna is just a normal short hertz antenna with poor efficiency and low RR. Well, the typical RR of a standard EH antenna is 2360 ohms. The antenna is a sort of a dipole, not need the ground at all. Now you can understand why is so efficient. The equivalent Circuit is a RC series . there is asmall L too but it is tuned out by the capacitor . Nobody can rephase a cap hence the RR has the V and I in phase and the C has the V and I 90 degrees apart. 5) the shape of the two elements (cylinders) and their proportion each other , are important to achieve the best fields integration 6) comparing a well built and well tuned EH against a vertical dipole ( or GP) must have NO differences . I read many comments about 1 Point S under...this is valid for the coil+link version . The full network version (tricky? yes a little..) shows no difference. a 14 mhz EH built using a 2" pipe support having the radiators about the 2% wavelenght, shows a bandwidth very large....about 1.5 MHZ at +-3db. (!!!) 97% of eff. almost NO noise on RX. 7) the building can be tricky. For this we decided to reveal all, no secrets. hence you can ask any help to me, I will be very happy to help everybody to have a complete success. remember the antennas must be compared at same heights and allowing some disyance each other to skip any reflections, absorbations. couplings. Since the beginning of this adventure , I read of antenna mounting ..everywhere !!! bathroom, kitchen, dining room and so on....you can not compare a dipole installed 20 meters high with an EH in the bsement inside the house. Yes the EH antenna is not sensitive to nearby objects... (remember the far field start at the antenna) BUT the signal can not be the same inside a house. Anyway I got amazing reports hamming inside !!! Be careful for body exposure at the rf. Dear friends I wanted summarize some points...I know there are so many things to say....hi.....I am available to discuss with you about it. It is my pleasure. have fun ! 73's steve IK5IIR | ||
| N0TONE | 2002-09-07 | |
|---|---|---|
| RE: Small EH Antenna | ||
| IK5IIR and my comments: >>>...I spent the last 4 years of my life on it. After so many measurements , tests, comments, long meetings at the ham clubs and so on, I would like add my poor contribute to the discussion.<<<< Excellent. Perhaps you can fill the void. So far, nobody has offered a good way to "measure" whether these antennas are actually EH-mode or not. Only comment I've ever seen is "if they are operating efficiently, then they must be EH mode." I disagree. I have a very conventional short antenna which is efficient - it's not EH at all. There MUST be a measurement technique that proves the EH theory. Without that, the concept is irrelevant. Particularly, we want to know more about your measurements. What have you measured? What test equipment do you use? I assume you measured impedance at many points, with a vector impedance device, and that you measured the E-field and H-field at close distances and at far distances, and measured the relative phases between them so that you could justify the claims about far-field happening very close to the antenna. None of the websites describes any of the test and measurement methods, and many of us really want somebody to fill that big hole. It would be extremely good if you showed photographs of your measurement setups, showing the test equipment with the results displayed on the meters or screens. >>>>1) is this a new concept? We think so.<<<<< But I ask - so what? Why should we care if it is a new concept? >>>>The traditional Hertz antennas use a current flowing on a conductor to produce a H field that in turn produce an E field.<<<< No. Hertz did not say that. Hertz' explanation involved the simultaneous creation of an E and an H field, 90 degrees apart from each other in time, orthogonal to each other in space, and orthogonal to the direction of propagation. It was Green, who later propsed that the numerical analysis of antennas could be completely carried out by ASSUMING that an H field "produced" an E field. His theory has often been debated, but we merrily use antenna software that assumes it's true. >>>In the EH antenna is the displacement current responsible of the H generation.<<<< This statement is in direct contradiction to Ampere's law. >>>>...with the EH antenna , the FAR field is bring close at the antenna , the Poynting theorem is satisfied and the electromagnetic wave travel in the medium.Yes the far field start at some inches from the antenna center.<<<< This claim can be easily validated by separate E and H field measurements using short electric and magnetic probes, which can be simply made from bits of coaxial cable. Why has nobody presented the results of these measurements on any of the web sites? A half day's work, with $10 in "new" equipment and you'd silence all the doubters. >>>>This takes some advantages on RX for instance. The antenna is sensitive at the electromagnetic wave and poor sensitive to the E and H field alone.the S/N ratio on Rx is improved by many dbs.practically on low bands is a pleasure receiving. <<<< Please point us to a website where you have stored .wav files comparing the EH versus something else on receive. >>>2)efficiency being the antenna based on the same physic laws and reaching a perfect integration of the two fields shows the same efficiency . We have a very low loss in the matching/phasing network , we can consider typically 3%. this takes to the declared efficiency of 97%. <<< Please explan the method by which you are able to measure these numbers. Engineers whose Ph.D. is in electromagnetics would never claim these numbers, even on the best aperture antennas ever made, so how can you? These are not numbers that one should be claiming, unless you can describe the method of measurement, well enough that others can duplicate it. >>>>3) The only version capable of the above efficiency is the full network version. The coil+link version may hve from 4 to 6 db of loss.<<<< That means that of 100 watts fed into it, 75 watts heats the coil. That should melt the coil described by KE0VH, made of 22 gauge wire. Does it? >>>> A simple coil can not achieve the requested phase to align perfectely the two fields. <<<< You have a one-port antenna drive. You have a one-port input to the network. You cannot derive ANY two-port network that separately adjusts the phasing of voltage and current, or can change the relative phase of them. Unless you're changing the laws of physics. >>>>4) equivalent circuit when the conditions to have the two fields aligned are satisfied , suddenly a high RR (radiation resistance) develops . This high RR was NOT there before. without the right phase shift on the network the EH antenna is just a normal short hertz antenna with poor efficiency and low RR. Well, the typical RR of a standard EH antenna is 2360 ohms. The antenna is a sort of a dipole, not need the ground at all. Now you can understand why is so efficient. The equivalent Circuit is a RC series .<<< First, this doesn't explain the efficiency. Second, these values are hard to believe. Please describe the method for measuring the numbers. If you are depending on mathematical de-embedding through the phasing network to calculate the values, present the equations. To date, I have not seen anybody successfully explain how these numbers were arrived at. What test equipment did you use? How did you calibrate it? What was the data reduction method? Please present schematics showing the probe entry points for the various measurement instruments that you used to produce these numbers. >>>there is asmall L too but it is tuned out by the capacitor . Nobody can rephase a cap hence the RR has the V and I in phase and the C has the V and I 90 degrees apart. <<< Likewise, if you have a series RC, there is a fixed, unchangeable phase relationship. Nobody can rephase it. >>>>5) the shape of the two elements (cylinders) and their proportion each other , are important to achieve the best fields integration <<<< Nothing in the propsed theory would result in this conclusion. Please provide the logical connection between theory and this result. >>>>>6) comparing a well built and well tuned EH against a vertical dipole ( or GP) must have NO differences . I read many comments about 1 Point S under...this is valid for the coil+link version . The full network version (tricky? yes a little..) shows no difference. a 14 mhz EH built using a 2" pipe support having the radiators about the 2% wavelenght, shows a bandwidth very large....about 1.5 MHZ at +-3db. (!!!) 97% of eff. almost NO noise on RX. <<<< Again, please describe the measurement equiment and method used to demonstrate 97% efficiency and 1.5 MHz bandwidth, and the 3dB. Also, what is the 3dB in reference to? Return loss? Gain? Efficiency? Something else? A dB is always relative to something else - what are your dB relative to? >>>>7) the building can be tricky. For this we decided to reveal all, no secrets.<<<< You have left a LOT of secrets. Particularly, you present many numerical values, for RR, for efficiency, and so on, but you and K0KPH have, to date, been utterly unwilling to describe how you arrived at those numbers. THAT is the secret and it is a crucial one. Physical details of dimensions and material used are utterly immaterial in comparison to knowing how you actually make your measurements. >>>> hence you can ask any help to me,<<<< I have hereby asked for help in explaining how you arrived at some of your numerical conclusions. >>>>Dear friends I wanted summarize some points...I know there are so many things to say....hi.....I am available to discuss with you about it. <<<< Excellent. I have asked some direct questions, and look forward eagerly to your direct answers. AM Reply to a comment by : IK5IIR on 2002-09-05 Hello dear friends, I am stefano (steve) IK5IIR . Kevin KE0VH told me he decided to post his famous article about the EH antennas on this forum . I carefully read all the comments and I want thank all of you to be so open minded , prepared, interested on this fascinating hobby. I am here just like an ham , loving on a total way the ham radio and the antennas on particular. I spent all my ham life homebrewing. Well this amazing new concept.....wow .... as many of you know, I spent the last 4 years of my life on it. After so many measurements , tests, comments, long meetings at the ham clubs and so on, I would like add my poor contribute to the discussion. I am just speaking as ham , I don't want on any way touch the commercial "reasons". I would like just clarify, chat, help ( if I can) have fun ..on this topic. 1) is this a new concept? We think so. The traditional Hertz antennas use a current flowing on a conductor to produce a H field that in turn produce an E field. these fields are 90 degrees apart in the space and 90 degrees apart timing.Well at 1/3 of a wavelenght (may be more ....) these fields appear to be in time phase a electromagnetic wave is generated and travel in the space. This antenna satisfy the Poynting theorem In the EH antenna is the displacement current responsible of the H generation . This is the main difference...not current in a conductor but still we have a H field and applied to two particular and funny plates of a capacitor . 90 degrees in time apart we have an E field also . These two fields are 90 degrees apart in the space also. Ok we have the same condition as above. The two fields are out of phase ....hence we added a special phasing/matching network (attention matching AND phasing) to allow the two fields alignement. doing this , with the EH antenna , the FAR field is bring close at the antenna , the Poynting theorem is satisfied and the electromagnetic wave travel in the medium.Yes the far field start at some inches from the antenna center. This takes some advantages on RX for instance. The antenna is sensitive at the electromagnetic wave and poor sensitive to the E and H field alone.the S/N ratio on Rx is improved by many dbs.practically on low bands is a pleasure receiving. as you see the two antennas ..hertz and EH work on the same principle but with different application. HENCE....new physic law? NO is wrong. same laws, different application. Of course I used a simplified message but I hope is clear enough. 2)efficiency being the antenna based on the same physic laws and reaching a perfect integration of the two fields shows the same efficiency . We have a very low loss in the matching/phasing network , we can consider typically 3%. this takes to the declared efficiency of 97%. 3) The only version capable of the above efficiency is the full network version. The coil+link version may hve from 4 to 6 db of loss. A simple coil can not achieve the requested phase to align perfectely the two fields. 4) equivalent circuit when the conditions to have the two fields aligned are satisfied , suddenly a high RR (radiation resistance) develops . This high RR was NOT there before. without the right phase shift on the network the EH antenna is just a normal short hertz antenna with poor efficiency and low RR. Well, the typical RR of a standard EH antenna is 2360 ohms. The antenna is a sort of a dipole, not need the ground at all. Now you can understand why is so efficient. The equivalent Circuit is a RC series . there is asmall L too but it is tuned out by the capacitor . Nobody can rephase a cap hence the RR has the V and I in phase and the C has the V and I 90 degrees apart. 5) the shape of the two elements (cylinders) and their proportion each other , are important to achieve the best fields integration 6) comparing a well built and well tuned EH against a vertical dipole ( or GP) must have NO differences . I read many comments about 1 Point S under...this is valid for the coil+link version . The full network version (tricky? yes a little..) shows no difference. a 14 mhz EH built using a 2" pipe support having the radiators about the 2% wavelenght, shows a bandwidth very large....about 1.5 MHZ at +-3db. (!!!) 97% of eff. almost NO noise on RX. 7) the building can be tricky. For this we decided to reveal all, no secrets. hence you can ask any help to me, I will be very happy to help everybody to have a complete success. remember the antennas must be compared at same heights and allowing some disyance each other to skip any reflections, absorbations. couplings. Since the beginning of this adventure , I read of antenna mounting ..everywhere !!! bathroom, kitchen, dining room and so on....you can not compare a dipole installed 20 meters high with an EH in the bsement inside the house. Yes the EH antenna is not sensitive to nearby objects... (remember the far field start at the antenna) BUT the signal can not be the same inside a house. Anyway I got amazing reports hamming inside !!! Be careful for body exposure at the rf. Dear friends I wanted summarize some points...I know there are so many things to say....hi.....I am available to discuss with you about it. It is my pleasure. have fun ! 73's steve IK5IIR | ||
| N0TONE | 2002-09-07 | |
|---|---|---|
| RE: Small EH Antenna | ||
| Grover, you're sharp. You've corrected a few of my errors, but there are a few places we still don't see eye to eye. Call it differing viewpoints; I believe we are both attempting to achieve the same thing - an accurate understanding. To wit: > >>I am aware that physically small antennas can be made with very decent radiation efficiency but that they almost invariably wind up as point-source radiators<< >>"Except that they all have nulls off the end." >Actually the null can be vanishingly small and neglected if the radiator is short enough. These are. Even a "vanishingly small" null has finite "beamwidth". Look at the gain of a very short vertical, say, 20 degrees from vertical, and then a high dipole at the same angle. The dipole is still delivering a LOT of energy straight up. However, the original point is still valid. Anybody who has room for a full-length dipole isn't paying any attention to this discussion anyway, so the comparison is irrelevant. >> >>A low (below lambda over 4) dipole can have a gain in excess of 5 dBi in its major lobe quite easily. << >>"At only lambda/4 off the ground, though, that main lobe is uselessly straight up. Ten minutes with NEC will show you that in the useful radiation angles from 5 to about 20 degrees, a dipole at only 1/4 wave off the lossy ground has negative gain compared with a point source." >>Not true, at an angle of 70 degrees from the vertical (20 degrees from the horizontal the gain is 3.11 dBi for a horizontal dipole. The 0 dBi angle is 13 Degrees above the horizon. For a vertical dipole (what we are sort of discussing with the EH design) the max gain is 0.41 dBi at 19 degrees above the horizon over reasonable ground (Eps = 13, sigma = 0.005). Grover, please check your simulator. Many of the NEC variants do a very bad job of performance predictions over REAL ground. I have done ground measurements in several places across the US, and every sample I've taken has worse conductivity than the "poor" selection in every NEC I've tried. My favourite prediction tool is a massive 3D electromagnetic simulator engine that runs on a massed PC array at UCal. Every time I build an antenna that I've modelled using that code, the measurements meet the predictions. This is not the case with NEC, which is admittedly not good with grounds. You should check your numbers, too. A dipole in free space does not have 3.15dBi at ANY angle. The same dipole can only achieve that number if it's placed over a ground model which is far better than anything that's practical. A sanity check on your simulator would be to make sure you achieve 2.15 dBi on the horizon for a free-space dipole, and that as you bring that antenna closer to your modelled ground, that number just goes down, and down, and down. There should be no angle at which the performance over ground is better than in free space, because with REAL ground, there is no such angle. 20 degrees, by the way, is only barely useful. >>Agreed. Still all in all, less gain available than a high horiz. dipole. Trade-off point is lambda over four in height for the dipole. Higer makes the dipole noticibly better than a vertical. Disagree. You seem to think that 20 degrees is a useful angle. Your target should be below 10 degrees, which requires the dipole to be at least halfwave high. There's a reason why 40 meter dipoles "come to life" at 70 feet in height, and 20 meter dipoles do the same at 35 feet. >>>>"If the antenna gets warm in operation, then it's lossy. The effort spent to reduce loss in the goal of improved "gain" will also yield an antenna that will not zorch itself. They go together." >>True indeed but a couple of hundred amperes of rf through a 8" wide piece of aluminum foil wound on a cardboard tube is a zorch recipe if ever there was one! I suspect you haven't tried it. Taking skin effect into account, what is the RF resistance of a 2" diameter aluminum tube? A very small fraction of an ohm. The actual heating loss of that tube can easily be below 10 watts, even with hundreds of amps flowing through it. We should be thankful for this, otherwise solid state RF power amplifiers wouldn't work, because that's the sort of current density we create in the bond wires inside the RF output transistors in our rigs. If 2 amps of RF is safe in a bond wire that's only 0.0007 inches in diameter, then I'm quite comfortable with 200 amps in a 2" diamter tube. Besides, the reports on heating in the so-called EH antennas have never mentioned the tubes heating - it's always been the resonating inductors. >>>>"Uh, maybe. The "typical" auto antenna intentionally uses conductor loss to match to 50 ohms. If the antenna were built with a low-loss loading coil, the base impedance would be low, about 8 ohms in the example you give. To "fix" this, antennas such as the Hamstik intentionally use small- gauge wire for the loading coil, to add loss resistance. That means the base drive point resistance is 50 ohms, making the transceiver happy. The more expensive screwdriver-type mobile antennas do use a low-loss coil, and deal with the low drive-point impedance with a matching transformer. That's why they work better, particularly on the lower frequencies." >>Actually the Hustler brand short verticals will do 1kW - these are what I was mostly referring to not the Hamsticks, my error. I've melted Hustler 40 meter resonators with 500 watts. The point is this: IF an 8 foot 40 meter antenna is 50 ohms resistive at the feedpoint, THEN the matching is being created by loss. Hustler's design does not reduce the loss, it only makes the surfaces larger so that they do not rise as much in temperature at the same dissipated power. An 8 foot long 40 meter whip SHOULD measure about 8-12 ohms at the base, and require a matching network at that point. >>>>Static capacitance is not a good indicator of rf capacitance -- on the other hand the numbers seem low even for static capacitance ie. 25 cm separation on a 10 sq meter parallel plate capacitor = 350 pF and fringing fields on a car body should at least triple that value. <<< Who said anything about static capacitance? I made my measurements at RF using a network analyzer. And, my vehicle is a truck. There is very little metal that's only 25 cm (10 inches) off the ground. Most of the vehicle is higher than that. Fringing fields on a large surface are completely ignorable - they're only significant on small surfaces. Even on the little 2.4mm RF connectors that I routinely analyze, they only account for a 10% error in capacitance, nowhere near 3X. Let's see, the truck is about 5ft wide and 11 ft long, that's 55 sq feet, so your 10 sq meter estimate is about 2X too high. >>>Actually they [evansecent modes] are parasitic loss modes and do take significant power from the source. Propogation with exponentially decaying amplitude is the proper definition. I'm curious - where does the power go? If it's lossy, that means something gets warm. Is it the air itself that gets warm? >>>"I'd never considered an evanescent mode in propagation in semi-free space before. I'll have to look this one up or model it, but I sense that this is a misconception altogether." >Tis slippery as the dickens as most waveguide texts try really hard to ignore it as a near field, non propagating mode... Wrong. I used to teach electromagnetics, and non-propagating evanescent modes INSIDE WAVEGUIDE were one of the first topics they introduced with waveguides. I've never seen a text that did not explicitly discuss them. Speaking of which, I did some analysis using a 3D simulator of waveguide modes. What turns out, is that in waveguide, the evanescent modes do not take any power at all. If the waveguide is long enough, they're simply a reflection back to the source. If the waveguide is short enough, some of the energy makes it to the other end, and can be coupled out, and that will change the apparent (frequency dependent) impedance at the input side of the waveguide. Still, that does not mean the same thing will happen in "ether". In a waveguide, evansecent modes are those where the waveguide dimensions are too small to allow propagation for that mode. I just can't imagine such a mode in free space. >>>>>>In truth, a relatively simple, stealth vertical will work better than the E- H.<< >>>>"No. The EH IS a relatively simply vertical stealth antenna. It is only the explanation of it that's attempting to make it complicated." >>Simple and inefficient.... As yet, this is the fact we're trying to understand. If they get hot, they're inefficient. If not, they're efficient, although probably not optimal in terms of radiation pattern. >>>>"If your house is new enough to have PVC downspouts, then it also has a nice, solidly conductive, aluminum sheath just underneath the siding. How effective will your 1/4 wave 20 meter vertical be when mounted 6" away from a solid sheet of aluminum? You need to get the antenna (whether "EH", vertical, etc) away from large solid conductors like that." >>>>Aluminum -- they still use aluminum? ;-) Figured wood siding or plastic -- correct, aluminum is no good! I'm not talking about the siding. UNDERNEATH the siding, there is an insulating layer, made of closed-cell foam, which is laminated with aluminum on both sides. This is an energy-efficiency requirement in most states (California being one exception - environmental consciousness here is in name only - if you can't see it, they don't do it). If you remove your wood siding, you will have exposed the aluminum underlayer, sometimes called the sheath. This aluminized layer was a building requirement in 1988 in Georgia, 1982 in Colorado, and 1978 in Michigan. I only know those data points because in those years, I was involved to one extent or another, in buildling a house in those states. You can buy this material from your local Home Depot as "rigid insulation". You can get it without the aluminum skins, but for new home construction, you're required to use it with the skins, because they form a radiant barrier. This stuff is just under your wood siding. >>>>"Watering won't help. The earth is too poor a conductor, and watering may improve it, but it's still too poor. In models and experiments, the amount of salt and other minerals required to make moist soil (or even a body of water) usefully conductive would kill any plant life." >>>>Sure it does -- rain water becomes far more conductive once it hits the pavement or lawn -- sigmas of 0.12 -0.2 are attainable -- not salt but CO2 and other stuff dissolved minerals, organic acid salts etc. will make it conductive. A sigma of 0.12 - 0.2 is worthless as a ground for a vertical. If your simulator allows you to directly enter the conductivity, you'll see that there is a dramatic difference merely going from a copper sheet to stainless steel under a vertical. To a vertical, a sigma of 0.12 - 0.2 may as well be a layer of carbon. You'd actually be better off with a sigma of 0.000, as it would simulate free space. Again, I've made these measurements in an antenna field. Even over Georgia's high-mineral soil, which was the most conductive I've worked, the measurable differences between soil which was parched, and soil after weeks of non-stop rain, was zilch. Sure, I could measure a dramatic difference in DC resistance, and even RF resistance, between two rods driven into the ground. But the difference in radiated field strength was completely un-measurable. >>>"A well-designed antenna with conductors that are the proper size will break down from voltage arcover first - not conductor meltdown." >>True -- my point is that the E-H is not well designed due to excessive currents in Al foil! But as I, and others have noted, it's not the Al foil that gets hot - it's the matching inductors. Clearly, the loss, therefore, is not in the Al. >>>Hope this helped, >>Grover It did. Grover, why don't you try it, and report back to us at what power the cardboard/foil zorches? I have not tried cardboard and foil. My own short fat verticals are made of 20 mil copper wrapped around delrin forms, and I used integrated broadband transformers, and inductors made from soft-drawn copper tubing. Mine are not "EH", they're just short fat verticals. Not mounted 0.5 meters off the ground - that's silly - but mounted, say, on a roof vent. Try that in EZNEC and you'll see it's pretty good. In fact, while you're doing that, EZNEC will allow you to model it with 2" diameter aluminum tube - see how much (if any) efficiency reduction that causes. This is what it's all about. Discussing right down to the nitty gritty what works and what doesn't. John Krauss once told me that a physically short antenna CAN be made to work effectively as well as a full sized antenna. You just don't have as much room for errors - like using 22 gauge wire for inductors in high current areas, like the original poster said he did. Oh, yes, I did come up with a zorch mode for mine. The sharp edges of the tops of the copper conductors arced. Not a loss mechanism, just corona discharge. So I ended up copper-welding copper balls to the tops to stop that little problem! AM Reply to a comment by : N0GV on 2002-09-05 "More significantly, comparisons with low dipoles are irrelevant comparisons. One must compare the proposed EH with vertical radiators, to avoid what you then pointed out - the low dipole, because it's a horizontal radiator, has lobes and nulls in vastly different directions than a vertical radiator." Precisely. >>I am aware that physically small antennas can be made with very decent radiation efficiency but that they almost invariably wind up as point-source radiators<< "Except that they all have nulls off the end." Actually the null can be vanishingly small and neglected if the radiator is short enough. These are. >>A low (below lambda over 4) dipole can have a gain in excess of 5 dBi in its major lobe quite easily. << "At only lambda/4 off the ground, though, that main lobe is uselessly straight up. Ten minutes with NEC will show you that in the useful radiation angles from 5 to about 20 degrees, a dipole at only 1/4 wave off the lossy ground has negative gain compared with a point source." Not true, at an angle of 70 degrees from the vertical (20 degrees from the horizontal the gain is 3.11 dBi for a horizontal dipole. The 0 dBi angle is 13 Degrees above the horizon. For a vertical dipole (what we are sort of discussing with the EH design) the max gain is 0.41 dBi at 19 degrees above the horizon over reasonable ground (Eps = 13, sigma = 0.005). "A vertical radiator, even if it's quite short, has a null in the straight-up direction, and a greater percentage of its radiation is in useful directions." Not really -- the size of the null varies with the length of the conductors -- a 0.2m long by 1m long vertical dipole 0.5m above ground at 14 MHz (perfect matching presumed) has a maximum of -2.11 dBi of gain at 29 degrees over the horizon. "Most vertical installations, however, are compromised by ineffective ground systems, or lossy traps or other loading systems." Agreed. Still all in all, less gain available than a high horiz. dipole. Trade-off point is lambda over four in height for the dipole. Higer makes the dipole noticibly better than a vertical. >>As has been mentioned, current handling is a large part of the problem in these antennas and great care should be used when playing with them to keep them from zorching themselves<< "If the antenna gets warm in operation, then it's lossy. The effort spent to reduce loss in the goal of improved "gain" will also yield an antenna that will not zorch itself. They go together." True indeed but a couple of hundred amperes of rf through a 8" wide piece of aluminum foil wound on a cardboard tube is a zorch recipe if ever there was one! >>>In addition to this there is the problem of ground losses as the high currents in the antenna set up correspondingly large currents in the ground surrounding the antenna leading to losses and local heating.<<< "This problem is fixed by having an elevated feedpoint. You are correct, if you are restricting your considerations to ground-mounted verticals with the feedpoint at ground level. There are many highly successful 160 meter DX hounds who are using extremely short verticals with almost no ground system - by using elevated feed antennas." Correct -- more specifically the key is in insuring that the current distribution is such that the high current regions of the antenna are as far removed from ground as possible. A 1m long tube sitting at 0.5m above ground cannot remove the high current region far enough to alleviate this problem. >>>All of these problems are seen in the typical auto antenna which at 8' or so in length is about 45% of a full-size 1/4 wavelength vertical on 20m BUT a typical car body is VERY conductive and couples fairly well to ground (about 1000-2000pF or better static coupling depending on vehicle size etc.). This reduces ground losses considerably.<<< "Uh, maybe. The "typical" auto antenna intentionally uses conductor loss to match to 50 ohms. If the antenna were built with a low-loss loading coil, the base impedance would be low, about 8 ohms in the example you give. To "fix" this, antennas such as the Hamstik intentionally use small- gauge wire for the loading coil, to add loss resistance. That means the base drive point resistance is 50 ohms, making the transceiver happy. The more expensive screwdriver-type mobile antennas do use a low-loss coil, and deal with the low drive-point impedance with a matching transformer. That's why they work better, particularly on the lower frequencies." Actually the Hustler brand short verticals will do 1kW - these are what I was mostly referring to not the Hamsticks, my error. "Also note that the car antennas work as well as they do not because they couple to the ground but exactly the opposite - they do NOT couple to the ground. They are, in effect, an elevated-feed antenna. I drove my truck onto an aluminum sheet and measured the capacitance from truck to sheet as about 70pF, not thousands. And, when I drive over a ravine, increasing the distance from ground (and lowering the capacitance), my signal strength improves. Take a car style Hamstik, and mount it in your backyard on the ground, and feed it against, for instance a ground rod (a much better contact with ground than a vehicle body), and the results are awful. It works much better mounted on a vehicle." Static capacitance is not a good indicator of rf capacitance -- on the other hand the numbers seem low even for static capacitance ie. 25 cm separation on a 10 sq meter parallel plate capacitor = 350 pF and fringing fields on a car body should at least triple that value. >>>Also notice that radiation efficiency as defined in this thread also includes non-propogating evanescent modes which, as far as the transmission of information over long distances is concerned are a loss yet which the calculations consider a part of the propagating wave. <<< "Evanescent modes, however, are displacement fields, and consume no power from the source. At least, if the modes you're discussing are the same as an evanescent mode in a waveguide." Actually they are parasitic loss modes and do take significant power from the source. Propogation with exponentially decaying amplitude is the proper definition. "I'd never considered an evanescent mode in propagation in semi-free space before. I'll have to look this one up or model it, but I sense that this is a misconception altogether." Tis slippery as the dickens as most waveguide texts try really hard to ignore it as a near field, non propagating mode... >>In truth, a relatively simple, stealth vertical will work better than the E- H.<< "No. The EH IS a relatively simply vertical stealth antenna. It is only the explanation of it that's attempting to make it complicated." Simple and inefficient.... >>>Heck -- hiding a 1/2" copper pipe in a 1" PVC pipe or PVC downspout from a 2 story house will get you a full-size 1/4 wave vertical on 20m<<< "If your house is new enough to have PVC downspouts, then it also has a nice, solidly conductive, aluminum sheath just underneath the siding. How effective will your 1/4 wave 20 meter vertical be when mounted 6" away from a solid sheet of aluminum? You need to get the antenna (whether "EH", vertical, etc) away from large solid conductors like that." Aluminum -- they still use aluminum? ;-) Figured wood siding or plastic -- correct, aluminum is no good! >>>Gain is ~3 dBi at 12 degrees above the horizon if you manage to sneak out a few radials in the grass (watering your lawn also helps ;-) )!<<< "Watering won't help. The earth is too poor a conductor, and watering may improve it, but it's still too poor. In models and experiments, the amount of salt and other minerals required to make moist soil (or even a body of water) usefully conductive would kill any plant life." Sure it does -- rain water becomes far more conductive once it hits the pavement or lawn -- sigmas of 0.12 -0.2 are attainable -- not salt but CO2 and other stuff dissolved minerals, organic acid salts etc. will make it conductive. >>This you can load up with several kW without any fear of meltdown..... << A"s I said before, if your antenna is in any risk of meltdown, then you have not correctly determined the major sources of loss and corrected them. An efficient radiator will not melt down. It is true that the vast majority of size-reduced commercial antennas are not efficient - that's why we should be building our own." True "A well-designed antenna with conductors that are the proper size will break down from voltage arcover first - not conductor meltdown." True -- my point is that the E-H is not well designed due to excessive currents in Al foil! "I agree with Grover's implied message. Build antennas. Experiment. If you MUST hide an antenna in a PVC downspout next to your thermal sheeth, it's still better than no antenna. There is NO situation where you cannot be on HF. I have had effective antennas made with 22 gauge wire snuck underneath shingles and routed as a loop. There's always a way." >>Oh well, enjoy and happy antenna making! << "I couldn't have said it better!" >>Grover Larkins << "AM" Hope this helped, Grover Reply to a comment by : N0TONE on 2002-09-04 N0GV, good to see someone is really putting some thought into the replies. Yours get me thinking, too. >>I've seen claims which say that the E-H design out-performs low dipoles, patently incorrect and not made here. << More significantly, comparisons with low dipoles are irrelevant comparisons. One must compare the proposed EH with vertical radiators, to avoid what you then pointed out - the low dipole, because it's a horizontal radiator, has lobes and nulls in vastly different directions than a vertical radiator. >>I am aware that physically small antennas can be made with very decent radiation efficiency but that they almost invariably wind up as point-source radiators<< Except that they all have nulls off the end. >>A low (below lambda over 4) dipole can have a gain in excess of 5 dBi in its major lobe quite easily. << At only lambda/4 off the ground, though, that main lobe is uselessly straight up. Ten minutes with NEC will show you that in the useful radiation angles from 5 to about 20 degrees, a dipole at only 1/4 wave off the lossy ground has negative gain compared with a point source. A vertical radiator, even if it's quite short, has a null in the straight-up direction, and a greater percentage of its radiation is in useful directions. Most vertical installations, however, are compromised by ineffective ground systems, or lossy traps or other loading systems. >>As has been mentioned, current handling is a large part of the problem in these antennas and great care should be used when playing with them to keep them from zorching themselves<< If the antenna gets warm in operation, then it's lossy. The effort spent to reduce loss in the goal of improved "gain" will also yield an antenna that will not zorch itself. They go together. >>>In addition to this there is the problem of ground losses as the high currents in the antenna set up correspondingly large currents in the ground surrounding the antenna leading to losses and local heating.<<< This problem is fixed by having an elevated feedpoint. You are correct, if you are restricting your considerations to ground-mounted verticals with the feedpoint at ground level. There are many highly successful 160 meter DX hounds who are using extremely short verticals with almost no ground system - by using elevated feed antennas. >>>All of these problems are seen in the typical auto antenna which at 8' or so in length is about 45% of a full-size 1/4 wavelength vertical on 20m BUT a typical car body is VERY conductive and couples fairly well to ground (about 1000-2000pF or better static coupling depending on vehicle size etc.). This reduces ground losses considerably.<<< Uh, maybe. The "typical" auto antenna intentionally uses conductor loss to match to 50 ohms. If the antenna were built with a low-loss loading coil, the base impedance would be low, about 8 ohms in the example you give. To "fix" this, antennas such as the Hamstik intentionally use small-gauge wire for the loading coil, to add loss resistance. That means the base drive point resistance is 50 ohms, making the transceiver happy. The more expensive screwdriver-type mobile antennas do use a low-loss coil, and deal with the low drive-point impedance with a matching transformer. That's why they work better, particularly on the lower frequencies. Also note that the car antennas work as well as they do not because they couple to the ground but exactly the opposite - they do NOT couple to the ground. They are, in effect, an elevated-feed antenna. I drove my truck onto an aluminum sheet and measured the capacitance from truck to sheet as about 70pF, not thousands. And, when I drive over a ravine, increasing the distance from ground (and lowering the capacitance), my signal strength improves. Take a car style Hamstik, and mount it in your backyard on the ground, and feed it against, for instance a ground rod (a much better contact with ground than a vehicle body), and the results are awful. It works much better mounted on a vehicle. >>>Also notice that radiation efficiency as defined in this thread also includes non-propogating evanescent modes which, as far as the transmission of information over long distances is concerned are a loss yet which the calculations consider a part of the propagating wave. <<< Evanescent modes, however, are displacement fields, and consume no power from the source. At least, if the modes you're discussing are the same as an evanescent mode in a waveguide. I'd never considered an evanescent mode in propagation in semi-free space before. I'll have to look this one up or model it, but I sense that this is a misconception altogether. >>In truth, a relatively simple, stealth vertical will work better than the E-H.<< No. The EH IS a relatively simply vertical stealth antenna. It is only the explanation of it that's attempting to make it complicated. >>>Heck -- hiding a 1/2" copper pipe in a 1" PVC pipe or PVC downspout from a 2 story house will get you a full-size 1/4 wave vertical on 20m<<< If your house is new enough to have PVC downspouts, then it also has a nice, solidly conductive, aluminum sheath just underneath the siding. How effective will your 1/4 wave 20 meter vertical be when mounted 6" away from a solid sheet of aluminum? You need to get the antenna (whether "EH", vertical, etc) away from large solid conductors like that. >>>Gain is ~3 dBi at 12 degrees above the horizon if you manage to sneak out a few radials in the grass (watering your lawn also helps ;-) )!<<< Watering won't help. The earth is too poor a conductor, and watering may improve it, but it's still too poor. In models and experiments, the amount of salt and other minerals required to make moist soil (or even a body of water) usefully conductive would kill any plant life. >>This you can load up with several kW without any fear of meltdown..... << As I said before, if your antenna is in any risk of meltdown, then you have not correctly determined the major sources of loss and corrected them. An efficient radiator will not melt down. It is true that the vast majority of size-reduced commercial antennas are not efficient - that's why we should be building our own. A well-designed antenna with conductors that are the proper size will break down from voltage arcover first - not conductor meltdown. I agree with Grover's implied message. Build antennas. Experiment. If you MUST hide an antenna in a PVC downspout next to your thermal sheeth, it's still better than no antenna. There is NO situation where you cannot be on HF. I have had effective antennas made with 22 gauge wire snuck underneath shingles and routed as a loop. There's always a way. Want to have success with this "EH"? Build it, dump power into it and see what gets warm. Whatever gets warm, improve it. Make it larger diameter, until it no longer gets warm. If 100 watts for 5 minutes doesn't get it warm, increase the power level. If 500 watts for 5 minutes doesn't get it warm, then you've succeeded in making the efficiency good. For comparisons, by the way, a Hamstick 20 meter car antenna, after 5 minutes of 100W key-down CW, was too warm to comfortably hold my hand on. And I've worked plenty of DX on 20 CW mobile. My model shows this 20 meter Hamstick to be about 10dB down from a full sized vertical, so I think 9dB down from a full-sized, well-installed antenna is still acceptable. 100W into such an antenna would be as effective as QRP into a full sized antenna, and the QRP folks do quite well. >>Oh well, enjoy and happy antenna making! << I couldn't have said it better! >>Grover Larkins << AM Reply to a comment by : N0GV on 2002-09-03 A few comments on the topic are again in order -- I've seen claims which say that the E-H design out-performs low dipoles, patently incorrect and not made here. I am aware that physically small antennas can be made with very decent radiation efficiency but that they almost invariably wind up as point-source radiators is always overlooked as is the fact that they radiate with a spherical pattern (one and the same actually). Only 9 dB down from a dipole is almost a meaningless figure if the station happens to be ~ 500 miles (800 km) away and the high angle reflection of the E-H "outperforms" the dipole by having stations in the null of the dipole compared with the E-H. My experience with short antennas would lead me to believe that a short, low, E-H antenna would be doing quite well to have a theoretical gain of a dB or so over isotropic. A low (below lambda over 4) dipole can have a gain in excess of 5 dBi in its major lobe quite easily. As has been mentioned, current handling is a large part of the problem in these antennas and great care should be used when playing with them to keep them from zorching themselves (cardboard tubes can ignite etc....) with moderate (400+ watt power levels). In addition to this there is the problem of ground losses as the high currents in the antenna set up correspondingly large currents in the ground surrounding the antenna leading to losses and local heating. All of these problems are seen in the typical auto antenna which at 8' or so in length is about 45% of a full-size 1/4 wavelength vertical on 20m BUT a typical car body is VERY conductive and couples fairly well to ground (about 1000-2000pF or better static coupling depending on vehicle size etc.). This reduces ground losses considerably. Also notice that radiation efficiency as defined in this thread also includes non-propogating evanescent modes which, as far as the transmission of information over long distances is concerned are a loss yet which the calculations consider a part of the propagating wave. In truth, a relatively simple, stealth vertical will work better than the E-H. It will have a wider bandwidth, a lower chance of ignition and less EMI potential and you can drive it with higher power levels..... If you need gain you can even phase a couple of them together to get a couple of dB of gain!!! Heck -- hiding a 1/2" copper pipe in a 1" PVC pipe or PVC downspout from a 2 story house will get you a full-size 1/4 wave vertical on 20m and I sincerely doubt that the neighborhood covenant Nazis will even see it or object to it! Gain is ~3 dBi at 12 degrees above the horizon if you manage to sneak out a few radials in the grass (watering your lawn also helps ;-) )! This you can load up with several kW without any fear of meltdown..... Oh well, enjoy and happy antenna making! Grover Larkins Reply to a comment by : N0TONE on 2002-09-03 N0GV, I am inclined to agree re: the patent claims. However, the patent claims are written with such double-talk (among other consulting activites which I perform, are patent investigations, and the language of this one is terribly difficult to wade through -worse than most). However, I am willing to set that aside for a different discussion, to address the issue of whether this antenna can, in fact, be a viable candidate as a small-profile radiator. In your posting, you acknowledged that the antenna's radiation is 9dB down from a low dipole - and mind, you, the antenna in question was mounted below that low dipole, so the antenna in question, mounted at the same height as the low dipole may have done better. Of course, a dipole is not the best antenna to compare with, given the orthoganal radiation patterrns one expects between a horizontal dipole and this so-called EH, which is principally a vertical dipole. However, it is notable that an antenna which is only 5% of the size it "should" be (14 inches versus 33 feet, for a 1/2 wave vertical dipole on 20 meters) and yet its radiation is ONLY 9dB down. That is nothing short of remarkable. I have performed measurements on many of the commercially available mobile whips, and at 8 feet long, very few of them are "only" 9dB down. 12dB is more the order of the day. I won't go into the detailed explanation, but for comparison purposes, you can expect the run-of-the-mill, center-loaded whip or trapped dipole to have reduced efficiency, to the tune of 10 log ( (length actual / length full-size)^2). The math is easy to work out - start by predicting the real part of the drive impedance (versus length), then resonate with inductance and add series loss resistance until you're back to 50 ohms. That's how the major manufacturers do it with their various loaded whips. I always look for good ideas. In this case, the idea of using large-diameter conductors in a shortened antenna to overcome the expected extremely high currents is a wonderful idea. The patent itself is irrelevant, so it matters not whether it's valid or not. By the way, in my homebrew foreshortened "fat" dipoles, I have measured efficiencies of about 25% for an antenna which is 10% of "full size", through similar techniques of using fat conductors, but paying more attention to low-loss tuning networks than have been shown so far. N0GV, try building one. Tune it so that the SWR is low, then shove 100W into it. Find out what gets warm, then alter the design (make something fatter) and test again. You will be surprised. Here is the true test of whether you have it tuned "right". You must have all of these conditions satisfied simulataneously: a) SWR is close to 1:1. Don't be happy with 2:1 b) You're measuring at your intended operating frequency c) The antenna is mounted where it's going to be used d) After driving the antenna with a 100W carrier for a full 15 minute, and then touching the antenna within 20 seconds after removing power, NOTHING is warm. If you can satisfy all four criteria at once, then you're turning all your RF into radiation (point source style). This does not prove the EH concept at all, but rather is a validation experiment for any small antenna. If you send RF power to an antenna, it can only go three place - into radiation, heat or reflected back to the transmitter. So, get the latter two items down to zero, and you've got a radiator. But it's a small one, and like any other small one, it's going to be near-isotropic in performance. Best case should be 2.15dB below a free-space dipole. And a free-space dipole is about 6dB BETTER than the average back-yard dipole at 50 feet. AM Reply to a comment by : N0GV on 2002-08-30 Gee --- And I guess that you guys are all impressed with an antenna which admittedly has more than 9 dB of loss as compared with a LOW dipole. (1 1/2 S units is 9 dB). Sure it radiates less but it makes a great space heater! About the lack of EMI -- the earlier poster had it right -- no signal = no EMI. I've read the patent and the theory behind it and it presumes that the E X H = S relationship does not apply for the Poynting vector! Sorry but it just ain't so -- the direction of propagation is normal to both the E and H fields and if either one of them drops to zero then it flat does not radiate! Likewise the Z0 of free space is proportional to the ratio of E(theta) to H(Phi) and we don't even want to begin thinking of rewriting the impedance of free space by increasing the relative permeability or permittivity of free space. Hence the result is pure bunk. On the other hand it is a really interesting way to take a several thousand dollar transciever capable of 100-200 Watts and turn it into a QRP rig! Seems there was an anecdotal story of a South Dakota contact using a dummy load as a radiator in a recent QST..... Please don't believe this garbage about the EH antenna as it is really, really, specious! Grover Larkins and, yes I have a EE degree (three in fact) and, yes I did indeed learn fields and waves from Bob Collin. Reply to a comment by : KD3V on 2002-08-20 !!! LISTEN UP SKEPTICS !!! Please stop making fools of yourselves! If you haven't tried it you have NO BASIS for saying anything! We made one! I used it! it works! I am an electrical engineer. I have been one since 1982. These EH antennas in fact: 1. ... are not "getting something for nothing", 2. they are not "changing the laws of physics in order to make something better than it is", 3. they agree completely with the law of physics that tells us how to get radiation, and for those that have taken the time to read the relevant website, this is called the "Poynting Theorem". This antenna is simple a DIFFERENT method to work this "law of physics". 4. They WORK! I know because I used one! I sent the article to a friend who wanted to make one, he had a friend of his duplicate the 20 meter version that was detailed on the web site. He used it and then I put it up in place on the roof. Simply put, I worked the world on it! I live in Hollywood Calif. From John in South Africa, a 5-7 ... on the LONG path... a FM5 in Martinique, VK's ZL's ZK1, you name it and I only had it for 3 days! So! Read the web sites! These antennas are not using feedline rariation, they are genuine rariators using a different method to create the crossed EM field and as a result they do not need the "linear" distance used by a diplole! These antennas just do it DIFFERENTLY! Yea, i get upset by the "ignorant" who speak up with no basis from which to do so. In the place of facts you put baseless opinion, and in the place of knowledge you put "authority". You are all only making fools of yourselves and those of us who take the time to "find out for ourselves" are the ones who gain real knowledge! We were curious so we built one and we found that it works! Simple. We didn't know until we tried... but we also didn't try to slam it until we KNEW something about which we wanted to speak! I would have posted a few photos but you can already see them when you go read the web site referenced! Ours looked just like theirs do. We used copper plate wrapped around PVC cylinder. Total length.. just like on the website! http://www.qsl.net/w0kph/ This is the link that describes the "full network" verion that our friend built. http://www.qsl.net/w0kph/fullnet.html | ||
| IK5IIR | 2002-09-05 | |
|---|---|---|
| Small EH Antenna | ||
| Hello dear friends, I am stefano (steve) IK5IIR . Kevin KE0VH told me he decided to post his famous article about the EH antennas on this forum . I carefully read all the comments and I want thank all of you to be so open minded , prepared, interested on this fascinating hobby. I am here just like an ham , loving on a total way the ham radio and the antennas on particular. I spent all my ham life homebrewing. Well this amazing new concept.....wow .... as many of you know, I spent the last 4 years of my life on it. After so many measurements , tests, comments, long meetings at the ham clubs and so on, I would like add my poor contribute to the discussion. I am just speaking as ham , I don't want on any way touch the commercial "reasons". I would like just clarify, chat, help ( if I can) have fun ..on this topic. 1) is this a new concept? We think so. The traditional Hertz antennas use a current flowing on a conductor to produce a H field that in turn produce an E field. these fields are 90 degrees apart in the space and 90 degrees apart timing.Well at 1/3 of a wavelenght (may be more ....) these fields appear to be in time phase a electromagnetic wave is generated and travel in the space. This antenna satisfy the Poynting theorem In the EH antenna is the displacement current responsible of the H generation . This is the main difference...not current in a conductor but still we have a H field and applied to two particular and funny plates of a capacitor . 90 degrees in time apart we have an E field also . These two fields are 90 degrees apart in the space also. Ok we have the same condition as above. The two fields are out of phase ....hence we added a special phasing/matching network (attention matching AND phasing) to allow the two fields alignement. doing this , with the EH antenna , the FAR field is bring close at the antenna , the Poynting theorem is satisfied and the electromagnetic wave travel in the medium.Yes the far field start at some inches from the antenna center. This takes some advantages on RX for instance. The antenna is sensitive at the electromagnetic wave and poor sensitive to the E and H field alone.the S/N ratio on Rx is improved by many dbs.practically on low bands is a pleasure receiving. as you see the two antennas ..hertz and EH work on the same principle but with different application. HENCE....new physic law? NO is wrong. same laws, different application. Of course I used a simplified message but I hope is clear enough. 2)efficiency being the antenna based on the same physic laws and reaching a perfect integration of the two fields shows the same efficiency . We have a very low loss in the matching/phasing network , we can consider typically 3%. this takes to the declared efficiency of 97%. 3) The only version capable of the above efficiency is the full network version. The coil+link version may hve from 4 to 6 db of loss. A simple coil can not achieve the requested phase to align perfectely the two fields. 4) equivalent circuit when the conditions to have the two fields aligned are satisfied , suddenly a high RR (radiation resistance) develops . This high RR was NOT there before. without the right phase shift on the network the EH antenna is just a normal short hertz antenna with poor efficiency and low RR. Well, the typical RR of a standard EH antenna is 2360 ohms. The antenna is a sort of a dipole, not need the ground at all. Now you can understand why is so efficient. The equivalent Circuit is a RC series . there is asmall L too but it is tuned out by the capacitor . Nobody can rephase a cap hence the RR has the V and I in phase and the C has the V and I 90 degrees apart. 5) the shape of the two elements (cylinders) and their proportion each other , are important to achieve the best fields integration 6) comparing a well built and well tuned EH against a vertical dipole ( or GP) must have NO differences . I read many comments about 1 Point S under...this is valid for the coil+link version . The full network version (tricky? yes a little..) shows no difference. a 14 mhz EH built using a 2" pipe support having the radiators about the 2% wavelenght, shows a bandwidth very large....about 1.5 MHZ at +-3db. (!!!) 97% of eff. almost NO noise on RX. 7) the building can be tricky. For this we decided to reveal all, no secrets. hence you can ask any help to me, I will be very happy to help everybody to have a complete success. remember the antennas must be compared at same heights and allowing some disyance each other to skip any reflections, absorbations. couplings. Since the beginning of this adventure , I read of antenna mounting ..everywhere !!! bathroom, kitchen, dining room and so on....you can not compare a dipole installed 20 meters high with an EH in the bsement inside the house. Yes the EH antenna is not sensitive to nearby objects... (remember the far field start at the antenna) BUT the signal can not be the same inside a house. Anyway I got amazing reports hamming inside !!! Be careful for body exposure at the rf. Dear friends I wanted summarize some points...I know there are so many things to say....hi.....I am available to discuss with you about it. It is my pleasure. have fun ! 73's steve IK5IIR | ||
| N0GV | 2002-09-05 | |
|---|---|---|
| RE: Small EH Antenna | ||
| "More significantly, comparisons with low dipoles are irrelevant comparisons. One must compare the proposed EH with vertical radiators, to avoid what you then pointed out - the low dipole, because it's a horizontal radiator, has lobes and nulls in vastly different directions than a vertical radiator." Precisely. >>I am aware that physically small antennas can be made with very decent radiation efficiency but that they almost invariably wind up as point-source radiators<< "Except that they all have nulls off the end." Actually the null can be vanishingly small and neglected if the radiator is short enough. These are. >>A low (below lambda over 4) dipole can have a gain in excess of 5 dBi in its major lobe quite easily. << "At only lambda/4 off the ground, though, that main lobe is uselessly straight up. Ten minutes with NEC will show you that in the useful radiation angles from 5 to about 20 degrees, a dipole at only 1/4 wave off the lossy ground has negative gain compared with a point source." Not true, at an angle of 70 degrees from the vertical (20 degrees from the horizontal the gain is 3.11 dBi for a horizontal dipole. The 0 dBi angle is 13 Degrees above the horizon. For a vertical dipole (what we are sort of discussing with the EH design) the max gain is 0.41 dBi at 19 degrees above the horizon over reasonable ground (Eps = 13, sigma = 0.005). "A vertical radiator, even if it's quite short, has a null in the straight-up direction, and a greater percentage of its radiation is in useful directions." Not really -- the size of the null varies with the length of the conductors -- a 0.2m long by 1m long vertical dipole 0.5m above ground at 14 MHz (perfect matching presumed) has a maximum of -2.11 dBi of gain at 29 degrees over the horizon. "Most vertical installations, however, are compromised by ineffective ground systems, or lossy traps or other loading systems." Agreed. Still all in all, less gain available than a high horiz. dipole. Trade-off point is lambda over four in height for the dipole. Higer makes the dipole noticibly better than a vertical. >>As has been mentioned, current handling is a large part of the problem in these antennas and great care should be used when playing with them to keep them from zorching themselves<< "If the antenna gets warm in operation, then it's lossy. The effort spent to reduce loss in the goal of improved "gain" will also yield an antenna that will not zorch itself. They go together." True indeed but a couple of hundred amperes of rf through a 8" wide piece of aluminum foil wound on a cardboard tube is a zorch recipe if ever there was one! >>>In addition to this there is the problem of ground losses as the high currents in the antenna set up correspondingly large currents in the ground surrounding the antenna leading to losses and local heating.<<< "This problem is fixed by having an elevated feedpoint. You are correct, if you are restricting your considerations to ground-mounted verticals with the feedpoint at ground level. There are many highly successful 160 meter DX hounds who are using extremely short verticals with almost no ground system - by using elevated feed antennas." Correct -- more specifically the key is in insuring that the current distribution is such that the high current regions of the antenna are as far removed from ground as possible. A 1m long tube sitting at 0.5m above ground cannot remove the high current region far enough to alleviate this problem. >>>All of these problems are seen in the typical auto antenna which at 8' or so in length is about 45% of a full-size 1/4 wavelength vertical on 20m BUT a typical car body is VERY conductive and couples fairly well to ground (about 1000-2000pF or better static coupling depending on vehicle size etc.). This reduces ground losses considerably.<<< "Uh, maybe. The "typical" auto antenna intentionally uses conductor loss to match to 50 ohms. If the antenna were built with a low-loss loading coil, the base impedance would be low, about 8 ohms in the example you give. To "fix" this, antennas such as the Hamstik intentionally use small- gauge wire for the loading coil, to add loss resistance. That means the base drive point resistance is 50 ohms, making the transceiver happy. The more expensive screwdriver-type mobile antennas do use a low-loss coil, and deal with the low drive-point impedance with a matching transformer. That's why they work better, particularly on the lower frequencies." Actually the Hustler brand short verticals will do 1kW - these are what I was mostly referring to not the Hamsticks, my error. "Also note that the car antennas work as well as they do not because they couple to the ground but exactly the opposite - they do NOT couple to the ground. They are, in effect, an elevated-feed antenna. I drove my truck onto an aluminum sheet and measured the capacitance from truck to sheet as about 70pF, not thousands. And, when I drive over a ravine, increasing the distance from ground (and lowering the capacitance), my signal strength improves. Take a car style Hamstik, and mount it in your backyard on the ground, and feed it against, for instance a ground rod (a much better contact with ground than a vehicle body), and the results are awful. It works much better mounted on a vehicle." Static capacitance is not a good indicator of rf capacitance -- on the other hand the numbers seem low even for static capacitance ie. 25 cm separation on a 10 sq meter parallel plate capacitor = 350 pF and fringing fields on a car body should at least triple that value. >>>Also notice that radiation efficiency as defined in this thread also includes non-propogating evanescent modes which, as far as the transmission of information over long distances is concerned are a loss yet which the calculations consider a part of the propagating wave. <<< "Evanescent modes, however, are displacement fields, and consume no power from the source. At least, if the modes you're discussing are the same as an evanescent mode in a waveguide." Actually they are parasitic loss modes and do take significant power from the source. Propogation with exponentially decaying amplitude is the proper definition. "I'd never considered an evanescent mode in propagation in semi-free space before. I'll have to look this one up or model it, but I sense that this is a misconception altogether." Tis slippery as the dickens as most waveguide texts try really hard to ignore it as a near field, non propagating mode... >>In truth, a relatively simple, stealth vertical will work better than the E- H.<< "No. The EH IS a relatively simply vertical stealth antenna. It is only the explanation of it that's attempting to make it complicated." Simple and inefficient.... >>>Heck -- hiding a 1/2" copper pipe in a 1" PVC pipe or PVC downspout from a 2 story house will get you a full-size 1/4 wave vertical on 20m<<< "If your house is new enough to have PVC downspouts, then it also has a nice, solidly conductive, aluminum sheath just underneath the siding. How effective will your 1/4 wave 20 meter vertical be when mounted 6" away from a solid sheet of aluminum? You need to get the antenna (whether "EH", vertical, etc) away from large solid conductors like that." Aluminum -- they still use aluminum? ;-) Figured wood siding or plastic -- correct, aluminum is no good! >>>Gain is ~3 dBi at 12 degrees above the horizon if you manage to sneak out a few radials in the grass (watering your lawn also helps ;-) )!<<< "Watering won't help. The earth is too poor a conductor, and watering may improve it, but it's still too poor. In models and experiments, the amount of salt and other minerals required to make moist soil (or even a body of water) usefully conductive would kill any plant life." Sure it does -- rain water becomes far more conductive once it hits the pavement or lawn -- sigmas of 0.12 -0.2 are attainable -- not salt but CO2 and other stuff dissolved minerals, organic acid salts etc. will make it conductive. >>This you can load up with several kW without any fear of meltdown..... << A"s I said before, if your antenna is in any risk of meltdown, then you have not correctly determined the major sources of loss and corrected them. An efficient radiator will not melt down. It is true that the vast majority of size-reduced commercial antennas are not efficient - that's why we should be building our own." True "A well-designed antenna with conductors that are the proper size will break down from voltage arcover first - not conductor meltdown." True -- my point is that the E-H is not well designed due to excessive currents in Al foil! "I agree with Grover's implied message. Build antennas. Experiment. If you MUST hide an antenna in a PVC downspout next to your thermal sheeth, it's still better than no antenna. There is NO situation where you cannot be on HF. I have had effective antennas made with 22 gauge wire snuck underneath shingles and routed as a loop. There's always a way." >>Oh well, enjoy and happy antenna making! << "I couldn't have said it better!" >>Grover Larkins << "AM" Hope this helped, Grover Reply to a comment by : N0TONE on 2002-09-04 N0GV, good to see someone is really putting some thought into the replies. Yours get me thinking, too. >>I've seen claims which say that the E-H design out-performs low dipoles, patently incorrect and not made here. << More significantly, comparisons with low dipoles are irrelevant comparisons. One must compare the proposed EH with vertical radiators, to avoid what you then pointed out - the low dipole, because it's a horizontal radiator, has lobes and nulls in vastly different directions than a vertical radiator. >>I am aware that physically small antennas can be made with very decent radiation efficiency but that they almost invariably wind up as point-source radiators<< Except that they all have nulls off the end. >>A low (below lambda over 4) dipole can have a gain in excess of 5 dBi in its major lobe quite easily. << At only lambda/4 off the ground, though, that main lobe is uselessly straight up. Ten minutes with NEC will show you that in the useful radiation angles from 5 to about 20 degrees, a dipole at only 1/4 wave off the lossy ground has negative gain compared with a point source. A vertical radiator, even if it's quite short, has a null in the straight-up direction, and a greater percentage of its radiation is in useful directions. Most vertical installations, however, are compromised by ineffective ground systems, or lossy traps or other loading systems. >>As has been mentioned, current handling is a large part of the problem in these antennas and great care should be used when playing with them to keep them from zorching themselves<< If the antenna gets warm in operation, then it's lossy. The effort spent to reduce loss in the goal of improved "gain" will also yield an antenna that will not zorch itself. They go together. >>>In addition to this there is the problem of ground losses as the high currents in the antenna set up correspondingly large currents in the ground surrounding the antenna leading to losses and local heating.<<< This problem is fixed by having an elevated feedpoint. You are correct, if you are restricting your considerations to ground-mounted verticals with the feedpoint at ground level. There are many highly successful 160 meter DX hounds who are using extremely short verticals with almost no ground system - by using elevated feed antennas. >>>All of these problems are seen in the typical auto antenna which at 8' or so in length is about 45% of a full-size 1/4 wavelength vertical on 20m BUT a typical car body is VERY conductive and couples fairly well to ground (about 1000-2000pF or better static coupling depending on vehicle size etc.). This reduces ground losses considerably.<<< Uh, maybe. The "typical" auto antenna intentionally uses conductor loss to match to 50 ohms. If the antenna were built with a low-loss loading coil, the base impedance would be low, about 8 ohms in the example you give. To "fix" this, antennas such as the Hamstik intentionally use small-gauge wire for the loading coil, to add loss resistance. That means the base drive point resistance is 50 ohms, making the transceiver happy. The more expensive screwdriver-type mobile antennas do use a low-loss coil, and deal with the low drive-point impedance with a matching transformer. That's why they work better, particularly on the lower frequencies. Also note that the car antennas work as well as they do not because they couple to the ground but exactly the opposite - they do NOT couple to the ground. They are, in effect, an elevated-feed antenna. I drove my truck onto an aluminum sheet and measured the capacitance from truck to sheet as about 70pF, not thousands. And, when I drive over a ravine, increasing the distance from ground (and lowering the capacitance), my signal strength improves. Take a car style Hamstik, and mount it in your backyard on the ground, and feed it against, for instance a ground rod (a much better contact with ground than a vehicle body), and the results are awful. It works much better mounted on a vehicle. >>>Also notice that radiation efficiency as defined in this thread also includes non-propogating evanescent modes which, as far as the transmission of information over long distances is concerned are a loss yet which the calculations consider a part of the propagating wave. <<< Evanescent modes, however, are displacement fields, and consume no power from the source. At least, if the modes you're discussing are the same as an evanescent mode in a waveguide. I'd never considered an evanescent mode in propagation in semi-free space before. I'll have to look this one up or model it, but I sense that this is a misconception altogether. >>In truth, a relatively simple, stealth vertical will work better than the E-H.<< No. The EH IS a relatively simply vertical stealth antenna. It is only the explanation of it that's attempting to make it complicated. >>>Heck -- hiding a 1/2" copper pipe in a 1" PVC pipe or PVC downspout from a 2 story house will get you a full-size 1/4 wave vertical on 20m<<< If your house is new enough to have PVC downspouts, then it also has a nice, solidly conductive, aluminum sheath just underneath the siding. How effective will your 1/4 wave 20 meter vertical be when mounted 6" away from a solid sheet of aluminum? You need to get the antenna (whether "EH", vertical, etc) away from large solid conductors like that. >>>Gain is ~3 dBi at 12 degrees above the horizon if you manage to sneak out a few radials in the grass (watering your lawn also helps ;-) )!<<< Watering won't help. The earth is too poor a conductor, and watering may improve it, but it's still too poor. In models and experiments, the amount of salt and other minerals required to make moist soil (or even a body of water) usefully conductive would kill any plant life. >>This you can load up with several kW without any fear of meltdown..... << As I said before, if your antenna is in any risk of meltdown, then you have not correctly determined the major sources of loss and corrected them. An efficient radiator will not melt down. It is true that the vast majority of size-reduced commercial antennas are not efficient - that's why we should be building our own. A well-designed antenna with conductors that are the proper size will break down from voltage arcover first - not conductor meltdown. I agree with Grover's implied message. Build antennas. Experiment. If you MUST hide an antenna in a PVC downspout next to your thermal sheeth, it's still better than no antenna. There is NO situation where you cannot be on HF. I have had effective antennas made with 22 gauge wire snuck underneath shingles and routed as a loop. There's always a way. Want to have success with this "EH"? Build it, dump power into it and see what gets warm. Whatever gets warm, improve it. Make it larger diameter, until it no longer gets warm. If 100 watts for 5 minutes doesn't get it warm, increase the power level. If 500 watts for 5 minutes doesn't get it warm, then you've succeeded in making the efficiency good. For comparisons, by the way, a Hamstick 20 meter car antenna, after 5 minutes of 100W key-down CW, was too warm to comfortably hold my hand on. And I've worked plenty of DX on 20 CW mobile. My model shows this 20 meter Hamstick to be about 10dB down from a full sized vertical, so I think 9dB down from a full-sized, well-installed antenna is still acceptable. 100W into such an antenna would be as effective as QRP into a full sized antenna, and the QRP folks do quite well. >>Oh well, enjoy and happy antenna making! << I couldn't have said it better! >>Grover Larkins << AM Reply to a comment by : N0GV on 2002-09-03 A few comments on the topic are again in order -- I've seen claims which say that the E-H design out-performs low dipoles, patently incorrect and not made here. I am aware that physically small antennas can be made with very decent radiation efficiency but that they almost invariably wind up as point-source radiators is always overlooked as is the fact that they radiate with a spherical pattern (one and the same actually). Only 9 dB down from a dipole is almost a meaningless figure if the station happens to be ~ 500 miles (800 km) away and the high angle reflection of the E-H "outperforms" the dipole by having stations in the null of the dipole compared with the E-H. My experience with short antennas would lead me to believe that a short, low, E-H antenna would be doing quite well to have a theoretical gain of a dB or so over isotropic. A low (below lambda over 4) dipole can have a gain in excess of 5 dBi in its major lobe quite easily. As has been mentioned, current handling is a large part of the problem in these antennas and great care should be used when playing with them to keep them from zorching themselves (cardboard tubes can ignite etc....) with moderate (400+ watt power levels). In addition to this there is the problem of ground losses as the high currents in the antenna set up correspondingly large currents in the ground surrounding the antenna leading to losses and local heating. All of these problems are seen in the typical auto antenna which at 8' or so in length is about 45% of a full-size 1/4 wavelength vertical on 20m BUT a typical car body is VERY conductive and couples fairly well to ground (about 1000-2000pF or better static coupling depending on vehicle size etc.). This reduces ground losses considerably. Also notice that radiation efficiency as defined in this thread also includes non-propogating evanescent modes which, as far as the transmission of information over long distances is concerned are a loss yet which the calculations consider a part of the propagating wave. In truth, a relatively simple, stealth vertical will work better than the E-H. It will have a wider bandwidth, a lower chance of ignition and less EMI potential and you can drive it with higher power levels..... If you need gain you can even phase a couple of them together to get a couple of dB of gain!!! Heck -- hiding a 1/2" copper pipe in a 1" PVC pipe or PVC downspout from a 2 story house will get you a full-size 1/4 wave vertical on 20m and I sincerely doubt that the neighborhood covenant Nazis will even see it or object to it! Gain is ~3 dBi at 12 degrees above the horizon if you manage to sneak out a few radials in the grass (watering your lawn also helps ;-) )! This you can load up with several kW without any fear of meltdown..... Oh well, enjoy and happy antenna making! Grover Larkins Reply to a comment by : N0TONE on 2002-09-03 N0GV, I am inclined to agree re: the patent claims. However, the patent claims are written with such double-talk (among other consulting activites which I perform, are patent investigations, and the language of this one is terribly difficult to wade through -worse than most). However, I am willing to set that aside for a different discussion, to address the issue of whether this antenna can, in fact, be a viable candidate as a small-profile radiator. In your posting, you acknowledged that the antenna's radiation is 9dB down from a low dipole - and mind, you, the antenna in question was mounted below that low dipole, so the antenna in question, mounted at the same height as the low dipole may have done better. Of course, a dipole is not the best antenna to compare with, given the orthoganal radiation patterrns one expects between a horizontal dipole and this so-called EH, which is principally a vertical dipole. However, it is notable that an antenna which is only 5% of the size it "should" be (14 inches versus 33 feet, for a 1/2 wave vertical dipole on 20 meters) and yet its radiation is ONLY 9dB down. That is nothing short of remarkable. I have performed measurements on many of the commercially available mobile whips, and at 8 feet long, very few of them are "only" 9dB down. 12dB is more the order of the day. I won't go into the detailed explanation, but for comparison purposes, you can expect the run-of-the-mill, center-loaded whip or trapped dipole to have reduced efficiency, to the tune of 10 log ( (length actual / length full-size)^2). The math is easy to work out - start by predicting the real part of the drive impedance (versus length), then resonate with inductance and add series loss resistance until you're back to 50 ohms. That's how the major manufacturers do it with their various loaded whips. I always look for good ideas. In this case, the idea of using large-diameter conductors in a shortened antenna to overcome the expected extremely high currents is a wonderful idea. The patent itself is irrelevant, so it matters not whether it's valid or not. By the way, in my homebrew foreshortened "fat" dipoles, I have measured efficiencies of about 25% for an antenna which is 10% of "full size", through similar techniques of using fat conductors, but paying more attention to low-loss tuning networks than have been shown so far. N0GV, try building one. Tune it so that the SWR is low, then shove 100W into it. Find out what gets warm, then alter the design (make something fatter) and test again. You will be surprised. Here is the true test of whether you have it tuned "right". You must have all of these conditions satisfied simulataneously: a) SWR is close to 1:1. Don't be happy with 2:1 b) You're measuring at your intended operating frequency c) The antenna is mounted where it's going to be used d) After driving the antenna with a 100W carrier for a full 15 minute, and then touching the antenna within 20 seconds after removing power, NOTHING is warm. If you can satisfy all four criteria at once, then you're turning all your RF into radiation (point source style). This does not prove the EH concept at all, but rather is a validation experiment for any small antenna. If you send RF power to an antenna, it can only go three place - into radiation, heat or reflected back to the transmitter. So, get the latter two items down to zero, and you've got a radiator. But it's a small one, and like any other small one, it's going to be near-isotropic in performance. Best case should be 2.15dB below a free-space dipole. And a free-space dipole is about 6dB BETTER than the average back-yard dipole at 50 feet. AM Reply to a comment by : N0GV on 2002-08-30 Gee --- And I guess that you guys are all impressed with an antenna which admittedly has more than 9 dB of loss as compared with a LOW dipole. (1 1/2 S units is 9 dB). Sure it radiates less but it makes a great space heater! About the lack of EMI -- the earlier poster had it right -- no signal = no EMI. I've read the patent and the theory behind it and it presumes that the E X H = S relationship does not apply for the Poynting vector! Sorry but it just ain't so -- the direction of propagation is normal to both the E and H fields and if either one of them drops to zero then it flat does not radiate! Likewise the Z0 of free space is proportional to the ratio of E(theta) to H(Phi) and we don't even want to begin thinking of rewriting the impedance of free space by increasing the relative permeability or permittivity of free space. Hence the result is pure bunk. On the other hand it is a really interesting way to take a several thousand dollar transciever capable of 100-200 Watts and turn it into a QRP rig! Seems there was an anecdotal story of a South Dakota contact using a dummy load as a radiator in a recent QST..... Please don't believe this garbage about the EH antenna as it is really, really, specious! Grover Larkins and, yes I have a EE degree (three in fact) and, yes I did indeed learn fields and waves from Bob Collin. Reply to a comment by : KD3V on 2002-08-20 !!! LISTEN UP SKEPTICS !!! Please stop making fools of yourselves! If you haven't tried it you have NO BASIS for saying anything! We made one! I used it! it works! I am an electrical engineer. I have been one since 1982. These EH antennas in fact: 1. ... are not "getting something for nothing", 2. they are not "changing the laws of physics in order to make something better than it is", 3. they agree completely with the law of physics that tells us how to get radiation, and for those that have taken the time to read the relevant website, this is called the "Poynting Theorem". This antenna is simple a DIFFERENT method to work this "law of physics". 4. They WORK! I know because I used one! I sent the article to a friend who wanted to make one, he had a friend of his duplicate the 20 meter version that was detailed on the web site. He used it and then I put it up in place on the roof. Simply put, I worked the world on it! I live in Hollywood Calif. From John in South Africa, a 5-7 ... on the LONG path... a FM5 in Martinique, VK's ZL's ZK1, you name it and I only had it for 3 days! So! Read the web sites! These antennas are not using feedline rariation, they are genuine rariators using a different method to create the crossed EM field and as a result they do not need the "linear" distance used by a diplole! These antennas just do it DIFFERENTLY! Yea, i get upset by the "ignorant" who speak up with no basis from which to do so. In the place of facts you put baseless opinion, and in the place of knowledge you put "authority". You are all only making fools of yourselves and those of us who take the time to "find out for ourselves" are the ones who gain real knowledge! We were curious so we built one and we found that it works! Simple. We didn't know until we tried... but we also didn't try to slam it until we KNEW something about which we wanted to speak! I would have posted a few photos but you can already see them when you go read the web site referenced! Ours looked just like theirs do. We used copper plate wrapped around PVC cylinder. Total length.. just like on the website! http://www.qsl.net/w0kph/ This is the link that describes the "full network" verion that our friend built. http://www.qsl.net/w0kph/fullnet.html | ||
| N0TONE | 2002-09-04 | |
|---|---|---|
| RE: Small EH Antenna | ||
| N0GV, good to see someone is really putting some thought into the replies. Yours get me thinking, too. >>I've seen claims which say that the E-H design out-performs low dipoles, patently incorrect and not made here. << More significantly, comparisons with low dipoles are irrelevant comparisons. One must compare the proposed EH with vertical radiators, to avoid what you then pointed out - the low dipole, because it's a horizontal radiator, has lobes and nulls in vastly different directions than a vertical radiator. >>I am aware that physically small antennas can be made with very decent radiation efficiency but that they almost invariably wind up as point-source radiators<< Except that they all have nulls off the end. >>A low (below lambda over 4) dipole can have a gain in excess of 5 dBi in its major lobe quite easily. << At only lambda/4 off the ground, though, that main lobe is uselessly straight up. Ten minutes with NEC will show you that in the useful radiation angles from 5 to about 20 degrees, a dipole at only 1/4 wave off the lossy ground has negative gain compared with a point source. A vertical radiator, even if it's quite short, has a null in the straight-up direction, and a greater percentage of its radiation is in useful directions. Most vertical installations, however, are compromised by ineffective ground systems, or lossy traps or other loading systems. >>As has been mentioned, current handling is a large part of the problem in these antennas and great care should be used when playing with them to keep them from zorching themselves<< If the antenna gets warm in operation, then it's lossy. The effort spent to reduce loss in the goal of improved "gain" will also yield an antenna that will not zorch itself. They go together. >>>In addition to this there is the problem of ground losses as the high currents in the antenna set up correspondingly large currents in the ground surrounding the antenna leading to losses and local heating.<<< This problem is fixed by having an elevated feedpoint. You are correct, if you are restricting your considerations to ground-mounted verticals with the feedpoint at ground level. There are many highly successful 160 meter DX hounds who are using extremely short verticals with almost no ground system - by using elevated feed antennas. >>>All of these problems are seen in the typical auto antenna which at 8' or so in length is about 45% of a full-size 1/4 wavelength vertical on 20m BUT a typical car body is VERY conductive and couples fairly well to ground (about 1000-2000pF or better static coupling depending on vehicle size etc.). This reduces ground losses considerably.<<< Uh, maybe. The "typical" auto antenna intentionally uses conductor loss to match to 50 ohms. If the antenna were built with a low-loss loading coil, the base impedance would be low, about 8 ohms in the example you give. To "fix" this, antennas such as the Hamstik intentionally use small-gauge wire for the loading coil, to add loss resistance. That means the base drive point resistance is 50 ohms, making the transceiver happy. The more expensive screwdriver-type mobile antennas do use a low-loss coil, and deal with the low drive-point impedance with a matching transformer. That's why they work better, particularly on the lower frequencies. Also note that the car antennas work as well as they do not because they couple to the ground but exactly the opposite - they do NOT couple to the ground. They are, in effect, an elevated-feed antenna. I drove my truck onto an aluminum sheet and measured the capacitance from truck to sheet as about 70pF, not thousands. And, when I drive over a ravine, increasing the distance from ground (and lowering the capacitance), my signal strength improves. Take a car style Hamstik, and mount it in your backyard on the ground, and feed it against, for instance a ground rod (a much better contact with ground than a vehicle body), and the results are awful. It works much better mounted on a vehicle. >>>Also notice that radiation efficiency as defined in this thread also includes non-propogating evanescent modes which, as far as the transmission of information over long distances is concerned are a loss yet which the calculations consider a part of the propagating wave. <<< Evanescent modes, however, are displacement fields, and consume no power from the source. At least, if the modes you're discussing are the same as an evanescent mode in a waveguide. I'd never considered an evanescent mode in propagation in semi-free space before. I'll have to look this one up or model it, but I sense that this is a misconception altogether. >>In truth, a relatively simple, stealth vertical will work better than the E-H.<< No. The EH IS a relatively simply vertical stealth antenna. It is only the explanation of it that's attempting to make it complicated. >>>Heck -- hiding a 1/2" copper pipe in a 1" PVC pipe or PVC downspout from a 2 story house will get you a full-size 1/4 wave vertical on 20m<<< If your house is new enough to have PVC downspouts, then it also has a nice, solidly conductive, aluminum sheath just underneath the siding. How effective will your 1/4 wave 20 meter vertical be when mounted 6" away from a solid sheet of aluminum? You need to get the antenna (whether "EH", vertical, etc) away from large solid conductors like that. >>>Gain is ~3 dBi at 12 degrees above the horizon if you manage to sneak out a few radials in the grass (watering your lawn also helps ;-) )!<<< Watering won't help. The earth is too poor a conductor, and watering may improve it, but it's still too poor. In models and experiments, the amount of salt and other minerals required to make moist soil (or even a body of water) usefully conductive would kill any plant life. >>This you can load up with several kW without any fear of meltdown..... << As I said before, if your antenna is in any risk of meltdown, then you have not correctly determined the major sources of loss and corrected them. An efficient radiator will not melt down. It is true that the vast majority of size-reduced commercial antennas are not efficient - that's why we should be building our own. A well-designed antenna with conductors that are the proper size will break down from voltage arcover first - not conductor meltdown. I agree with Grover's implied message. Build antennas. Experiment. If you MUST hide an antenna in a PVC downspout next to your thermal sheeth, it's still better than no antenna. There is NO situation where you cannot be on HF. I have had effective antennas made with 22 gauge wire snuck underneath shingles and routed as a loop. There's always a way. Want to have success with this "EH"? Build it, dump power into it and see what gets warm. Whatever gets warm, improve it. Make it larger diameter, until it no longer gets warm. If 100 watts for 5 minutes doesn't get it warm, increase the power level. If 500 watts for 5 minutes doesn't get it warm, then you've succeeded in making the efficiency good. For comparisons, by the way, a Hamstick 20 meter car antenna, after 5 minutes of 100W key-down CW, was too warm to comfortably hold my hand on. And I've worked plenty of DX on 20 CW mobile. My model shows this 20 meter Hamstick to be about 10dB down from a full sized vertical, so I think 9dB down from a full-sized, well-installed antenna is still acceptable. 100W into such an antenna would be as effective as QRP into a full sized antenna, and the QRP folks do quite well. >>Oh well, enjoy and happy antenna making! << I couldn't have said it better! >>Grover Larkins << AM Reply to a comment by : N0GV on 2002-09-03 A few comments on the topic are again in order -- I've seen claims which say that the E-H design out-performs low dipoles, patently incorrect and not made here. I am aware that physically small antennas can be made with very decent radiation efficiency but that they almost invariably wind up as point-source radiators is always overlooked as is the fact that they radiate with a spherical pattern (one and the same actually). Only 9 dB down from a dipole is almost a meaningless figure if the station happens to be ~ 500 miles (800 km) away and the high angle reflection of the E-H "outperforms" the dipole by having stations in the null of the dipole compared with the E-H. My experience with short antennas would lead me to believe that a short, low, E-H antenna would be doing quite well to have a theoretical gain of a dB or so over isotropic. A low (below lambda over 4) dipole can have a gain in excess of 5 dBi in its major lobe quite easily. As has been mentioned, current handling is a large part of the problem in these antennas and great care should be used when playing with them to keep them from zorching themselves (cardboard tubes can ignite etc....) with moderate (400+ watt power levels). In addition to this there is the problem of ground losses as the high currents in the antenna set up correspondingly large currents in the ground surrounding the antenna leading to losses and local heating. All of these problems are seen in the typical auto antenna which at 8' or so in length is about 45% of a full-size 1/4 wavelength vertical on 20m BUT a typical car body is VERY conductive and couples fairly well to ground (about 1000-2000pF or better static coupling depending on vehicle size etc.). This reduces ground losses considerably. Also notice that radiation efficiency as defined in this thread also includes non-propogating evanescent modes which, as far as the transmission of information over long distances is concerned are a loss yet which the calculations consider a part of the propagating wave. In truth, a relatively simple, stealth vertical will work better than the E-H. It will have a wider bandwidth, a lower chance of ignition and less EMI potential and you can drive it with higher power levels..... If you need gain you can even phase a couple of them together to get a couple of dB of gain!!! Heck -- hiding a 1/2" copper pipe in a 1" PVC pipe or PVC downspout from a 2 story house will get you a full-size 1/4 wave vertical on 20m and I sincerely doubt that the neighborhood covenant Nazis will even see it or object to it! Gain is ~3 dBi at 12 degrees above the horizon if you manage to sneak out a few radials in the grass (watering your lawn also helps ;-) )! This you can load up with several kW without any fear of meltdown..... Oh well, enjoy and happy antenna making! Grover Larkins Reply to a comment by : N0TONE on 2002-09-03 N0GV, I am inclined to agree re: the patent claims. However, the patent claims are written with such double-talk (among other consulting activites which I perform, are patent investigations, and the language of this one is terribly difficult to wade through -worse than most). However, I am willing to set that aside for a different discussion, to address the issue of whether this antenna can, in fact, be a viable candidate as a small-profile radiator. In your posting, you acknowledged that the antenna's radiation is 9dB down from a low dipole - and mind, you, the antenna in question was mounted below that low dipole, so the antenna in question, mounted at the same height as the low dipole may have done better. Of course, a dipole is not the best antenna to compare with, given the orthoganal radiation patterrns one expects between a horizontal dipole and this so-called EH, which is principally a vertical dipole. However, it is notable that an antenna which is only 5% of the size it "should" be (14 inches versus 33 feet, for a 1/2 wave vertical dipole on 20 meters) and yet its radiation is ONLY 9dB down. That is nothing short of remarkable. I have performed measurements on many of the commercially available mobile whips, and at 8 feet long, very few of them are "only" 9dB down. 12dB is more the order of the day. I won't go into the detailed explanation, but for comparison purposes, you can expect the run-of-the-mill, center-loaded whip or trapped dipole to have reduced efficiency, to the tune of 10 log ( (length actual / length full-size)^2). The math is easy to work out - start by predicting the real part of the drive impedance (versus length), then resonate with inductance and add series loss resistance until you're back to 50 ohms. That's how the major manufacturers do it with their various loaded whips. I always look for good ideas. In this case, the idea of using large-diameter conductors in a shortened antenna to overcome the expected extremely high currents is a wonderful idea. The patent itself is irrelevant, so it matters not whether it's valid or not. By the way, in my homebrew foreshortened "fat" dipoles, I have measured efficiencies of about 25% for an antenna which is 10% of "full size", through similar techniques of using fat conductors, but paying more attention to low-loss tuning networks than have been shown so far. N0GV, try building one. Tune it so that the SWR is low, then shove 100W into it. Find out what gets warm, then alter the design (make something fatter) and test again. You will be surprised. Here is the true test of whether you have it tuned "right". You must have all of these conditions satisfied simulataneously: a) SWR is close to 1:1. Don't be happy with 2:1 b) You're measuring at your intended operating frequency c) The antenna is mounted where it's going to be used d) After driving the antenna with a 100W carrier for a full 15 minute, and then touching the antenna within 20 seconds after removing power, NOTHING is warm. If you can satisfy all four criteria at once, then you're turning all your RF into radiation (point source style). This does not prove the EH concept at all, but rather is a validation experiment for any small antenna. If you send RF power to an antenna, it can only go three place - into radiation, heat or reflected back to the transmitter. So, get the latter two items down to zero, and you've got a radiator. But it's a small one, and like any other small one, it's going to be near-isotropic in performance. Best case should be 2.15dB below a free-space dipole. And a free-space dipole is about 6dB BETTER than the average back-yard dipole at 50 feet. AM Reply to a comment by : N0GV on 2002-08-30 Gee --- And I guess that you guys are all impressed with an antenna which admittedly has more than 9 dB of loss as compared with a LOW dipole. (1 1/2 S units is 9 dB). Sure it radiates less but it makes a great space heater! About the lack of EMI -- the earlier poster had it right -- no signal = no EMI. I've read the patent and the theory behind it and it presumes that the E X H = S relationship does not apply for the Poynting vector! Sorry but it just ain't so -- the direction of propagation is normal to both the E and H fields and if either one of them drops to zero then it flat does not radiate! Likewise the Z0 of free space is proportional to the ratio of E(theta) to H(Phi) and we don't even want to begin thinking of rewriting the impedance of free space by increasing the relative permeability or permittivity of free space. Hence the result is pure bunk. On the other hand it is a really interesting way to take a several thousand dollar transciever capable of 100-200 Watts and turn it into a QRP rig! Seems there was an anecdotal story of a South Dakota contact using a dummy load as a radiator in a recent QST..... Please don't believe this garbage about the EH antenna as it is really, really, specious! Grover Larkins and, yes I have a EE degree (three in fact) and, yes I did indeed learn fields and waves from Bob Collin. Reply to a comment by : KD3V on 2002-08-20 !!! LISTEN UP SKEPTICS !!! Please stop making fools of yourselves! If you haven't tried it you have NO BASIS for saying anything! We made one! I used it! it works! I am an electrical engineer. I have been one since 1982. These EH antennas in fact: 1. ... are not "getting something for nothing", 2. they are not "changing the laws of physics in order to make something better than it is", 3. they agree completely with the law of physics that tells us how to get radiation, and for those that have taken the time to read the relevant website, this is called the "Poynting Theorem". This antenna is simple a DIFFERENT method to work this "law of physics". 4. They WORK! I know because I used one! I sent the article to a friend who wanted to make one, he had a friend of his duplicate the 20 meter version that was detailed on the web site. He used it and then I put it up in place on the roof. Simply put, I worked the world on it! I live in Hollywood Calif. From John in South Africa, a 5-7 ... on the LONG path... a FM5 in Martinique, VK's ZL's ZK1, you name it and I only had it for 3 days! So! Read the web sites! These antennas are not using feedline rariation, they are genuine rariators using a different method to create the crossed EM field and as a result they do not need the "linear" distance used by a diplole! These antennas just do it DIFFERENTLY! Yea, i get upset by the "ignorant" who speak up with no basis from which to do so. In the place of facts you put baseless opinion, and in the place of knowledge you put "authority". You are all only making fools of yourselves and those of us who take the time to "find out for ourselves" are the ones who gain real knowledge! We were curious so we built one and we found that it works! Simple. We didn't know until we tried... but we also didn't try to slam it until we KNEW something about which we wanted to speak! I would have posted a few photos but you can already see them when you go read the web site referenced! Ours looked just like theirs do. We used copper plate wrapped around PVC cylinder. Total length.. just like on the website! http://www.qsl.net/w0kph/ This is the link that describes the "full network" verion that our friend built. http://www.qsl.net/w0kph/fullnet.html | ||
| AC6IJ | 2002-09-04 | |
|---|---|---|
| RE: Small EH Antenna | ||
| Hi, I stated earlier in this article that my attempt to make an EH antenna for 20 meters turned out to be a dissaster however after getting straightened out by Jeff, KA1OGM, I discovered that I had the wiring wrong. It now works just great and I have made 3 contacts today on PSK-31. I will be happy to send anyone who wants the final plans to an EH 20 antenna via email. Bill normally@softcom.net Reply to a comment by : OK1FOU on 2002-09-02 Dear DONTHAVEONEYET, the best place for transmitter schematics is ... the internet. Try a search with "transmitter schematic" (or add "ham radio" to make sure it will be for amateur radio). Try to http://come.to/sm0vpo. Or try another one: Just yesterday I built a small CW transmitter for 80 meters with a ceramic resonator. It can be tuned from 3503.6 to 3591.5 with a 15-500 pF variable capacitor. I use it as a test generator only, but according to OK1ACP, the original author, it delivers as much as 100 mW output with only two transistors... If you send me your email address, I'll try to make up some drawing of the schema. Regards, Jindra OK1FOU@centrum.cz Reply to a comment by : DONTHAVEONEYET on 2002-08-30 I'm still debating about it. This doesn't seem like critisism, more like a flame war from the days when I used to frequent slashdot. I stopped going there for this very reason: tired of people trying to shout loud enough to make others think they are right, the other guy is wrong, and that's that. All I'm saying is try it, post your results, then shut up and let someone else talk instead of just flaming from the get-go. Thought most hams were at least mature enough to do that. Side note: anyone know a good place to go for radio schematics? I'm thinking of building my transmitter instead of buying (financial concerns) but I can't seem to find anything online without having to buy a membership somewhere. Reply to a comment by : N0TONE on 2002-08-29 W5LF, yours was a good post, marred by some slight technical errors. First, a dipole antenna is neither electrical nor magnetic in its normal operation. For analysis purposes, programs like NEC focus exclusively on the currents and ignore the voltages. This is only for analytical convenience. NEC makes assumptions about the electric fields generated as a result of the existence of the currents and the associated magnetic fields. It would be just as easy to create software that focused exclusively on the electric voltages appearing on the antenna, and then surmised magnetic properties from them. It would be more correct to say that a dipole antenna creates both electric and magnetic fields, in a ratio appropriate to create a dipole's characteristic far field patterns. Your small loops are known as "magnetic" antennas not becaus they create ONLY a magnetic field, but because the ratio of magnetic to electric field in the near field is predominantly magnetic. As you move away from the small antenna, the fields take on the characteristic ratio of 377 (voltage field / magnetic field) which is true for a plane wave in free space, no matter what kind of radiator produced it. You said, "With a radiation resistance of .01 ohm or less, you get very high voltages (my magnetic loop gives me about 4.7kv on the capacitor at 7 mhz)..." There's a step missing in there. If you feed an antenna with a low radiation resistance at a current node, you get a high current, low voltage situation. If you feed it at a voltage node, you get high voltage and low current. Your capacitor, which you say is experiencing 4.7kV (you did not mention the power at which this occurs) is also experiencing huge currents. For instance, if it's tuned to 200 pF on 20 meters, and really experiencing 4.7kV, then it's also enduring nearly 120 amps. Fact is, super-short antennas have some points that are extremely high current, and some that are extemely high voltage, and some points where there's a bit of both. You're probably coupling into that antenna with a smaller, inner loop. That's because it is so difficult to physically break that loop without incurring resistive loss. The "EH" (I put in quotes because I do not believe there's a new principle involved) antenna, if viewed as a short dipole, is not a magnetic antenna like your loop, but is more appropriately an electric antenna. In the near field, the electric field is large compared to the magnetic field - the ratio is not 377, but much higher. This antenna will also require very low loss matching components. Because it's fed by breaking in the middle, the matching topology is different from your mag loop. I would expect, since it develops a strong electric field and weak magnetic field (in the near field), and most RFI is caused by magnetic coupling, this antenna could very well cause less RFI than a full sized antenna. Again, once you're some distance from the antenna, the radiation becomes planar and the 377 ratio must hold. I have to keep saying it - there's no reason why this antenna cannot work. But we must keep the claims reasonable. The theoretical limit is that it can work as well as a well-built 1/4 wave vertical and no better. A well-built 1/4 wave vertical will have better DX performance than a dipole, unless the dipole is mounted very high. I have read reports from many who've built this antenna, and it seems that nobody with a well-built vertical has built one of these. When they describe their comparison antennas, it seems that there's always a problem in the "reference" antenna. So what they're really finding out is that if they build a small antenna correctly, it can outperform a full-sized antenna built improperly. So - capable of decent performance? Yes. New technology? No. Can it beat a well-built full-sized vertical? No. But few full-sized verticals are built right. AM Reply to a comment by : W5LF on 2002-08-27 Anyone hear of a magnetic loop? 1/4th wavelength or smaller in total diameter, usually they are 1/10th or so. AEA made one, MFJ makes two, German and other companies make them commercially into the thousands of dollars, etc. they work on the same magnetic principle that the CCA, DDA etc magnetic antennas do, the magnetic field of the radio wave and not the electrical. A diapole has both but it was made for the electrical field (but still has its magnetic field). My lawn sprinklers never were bothered with my dipole but came on every time I transmitted with my CFA! (until I put some toroids on its cables). No one is re-writing theory here, no new laws written or old ones discarded. I personally haven't made a network (tuner section) that made me happy with my DDA antenna which stood about 14" high and 4" diameter. However, my 10' circumference loop made from 2" copper pipe (about 3' diameter) using a 15-500pf vacuum variable works wonderfully from 6.5 to 26.5 mhz (too much capacitance for 10 meters). its top performer for 20-15 meters and ok on 40 where its efficiency is down. Don't write anything off until you spend alot of time with it. There are VERY qualified authors and engineers studying and making these. One thing you can't absolutely ever forget, component quality is a absolute requirement with any magnetic antenna. With a radiation resistance of .01 ohm or less, you get very high voltages (my magnetic loop gives me about 4.7kv on the capacitor at 7 mhz) and current. Standard capacitors are out as wiper connections to the rotor (and resistance between plate connections, etc) all have resistive losses, vacuum variables or items such as butterfly capacitors are in, but only if the butterfly caps plates are welded together! See what I mean? Different requirements for this stuff but it can be very fun to mess with. My loop antenna at 10 feet operates as well as my dipole at 30 and the loop has almost no noise. I compare it to a beverage for a low noise floor. Experiment! Ham radio can be fun again if you do. | ||
| CENTIGRADE | 2002-09-04 | |
|---|---|---|
| Small EH Antenna | ||
| Extremly interesting article. Although i share neither the degree of optimism of its author nor (even less) the unimaginative block-headed criticisms of a couple of the comments posted here, i am sufficiently impressed with the concept to give it a try and investigate its practicality in urban locales where antennae are extremely difficult to "blend into the background" (so to speak). I will certainly check this out further and would like to build a 40m and an 80m version. I do not see any reason to debunk this very thoughtful article and do wish to commend its author for writing it. It is one of the most interesting and thought provoking articles i have seen published here because it is one of VERY FEW that have motivated THOUGHT on anything. K4XX and i have been involved with some experimentation with J-Poles and have discovered that the old well-known formula to compute resonant length, viz: 300/MHz may no longer prove accurate as either (a) the physical mass or (b) the surface area of the antenna increases. We have noted that as the physical mass / surface area increase, the resonant length has actually been observed to decrease by over 30%. What this means is that an antenna designed as a 5/8 wave vertical will be resonant at LESS THAN 1/2 of a physical wave length!! So why would one need rocket science credentials to understand that electrical wavelength and physical wavelength may be quite different from one another at a given resonant frequency? K5ET once made a QSO from NH to Chicago using a light bulb. Was the light bulb working as a sort of isotropic radiator? Or was the feedline radiating? It has already been proven that as either the mass or the surface area of an antenna increases, its physical length to achieve resonance decreases. So let us consider the isotropic case as one commenter has proposed: If the efficiency of the isotropic radiator is only 2.15 db below that of a dipole, what is so bad about that? Would it not be worth our while to investigate further the characteristics, vicissitudes, and practicability of this antenna concept? It is certainly ripe for investigation and is begging for experimentation. I think we should give it a try first, then opine to our heart's content AFTER we have some hard data upon which to opine in the first place. 73 de -Centigrade- | ||
| N0GV | 2002-09-03 | |
|---|---|---|
| RE: Small EH Antenna | ||
| A few comments on the topic are again in order -- I've seen claims which say that the E-H design out-performs low dipoles, patently incorrect and not made here. I am aware that physically small antennas can be made with very decent radiation efficiency but that they almost invariably wind up as point-source radiators is always overlooked as is the fact that they radiate with a spherical pattern (one and the same actually). Only 9 dB down from a dipole is almost a meaningless figure if the station happens to be ~ 500 miles (800 km) away and the high angle reflection of the E-H "outperforms" the dipole by having stations in the null of the dipole compared with the E-H. My experience with short antennas would lead me to believe that a short, low, E-H antenna would be doing quite well to have a theoretical gain of a dB or so over isotropic. A low (below lambda over 4) dipole can have a gain in excess of 5 dBi in its major lobe quite easily. As has been mentioned, current handling is a large part of the problem in these antennas and great care should be used when playing with them to keep them from zorching themselves (cardboard tubes can ignite etc....) with moderate (400+ watt power levels). In addition to this there is the problem of ground losses as the high currents in the antenna set up correspondingly large currents in the ground surrounding the antenna leading to losses and local heating. All of these problems are seen in the typical auto antenna which at 8' or so in length is about 45% of a full-size 1/4 wavelength vertical on 20m BUT a typical car body is VERY conductive and couples fairly well to ground (about 1000-2000pF or better static coupling depending on vehicle size etc.). This reduces ground losses considerably. Also notice that radiation efficiency as defined in this thread also includes non-propogating evanescent modes which, as far as the transmission of information over long distances is concerned are a loss yet which the calculations consider a part of the propagating wave. In truth, a relatively simple, stealth vertical will work better than the E-H. It will have a wider bandwidth, a lower chance of ignition and less EMI potential and you can drive it with higher power levels..... If you need gain you can even phase a couple of them together to get a couple of dB of gain!!! Heck -- hiding a 1/2" copper pipe in a 1" PVC pipe or PVC downspout from a 2 story house will get you a full-size 1/4 wave vertical on 20m and I sincerely doubt that the neighborhood covenant Nazis will even see it or object to it! Gain is ~3 dBi at 12 degrees above the horizon if you manage to sneak out a few radials in the grass (watering your lawn also helps ;-) )! This you can load up with several kW without any fear of meltdown..... Oh well, enjoy and happy antenna making! Grover Larkins Reply to a comment by : N0TONE on 2002-09-03 N0GV, I am inclined to agree re: the patent claims. However, the patent claims are written with such double-talk (among other consulting activites which I perform, are patent investigations, and the language of this one is terribly difficult to wade through -worse than most). However, I am willing to set that aside for a different discussion, to address the issue of whether this antenna can, in fact, be a viable candidate as a small-profile radiator. In your posting, you acknowledged that the antenna's radiation is 9dB down from a low dipole - and mind, you, the antenna in question was mounted below that low dipole, so the antenna in question, mounted at the same height as the low dipole may have done better. Of course, a dipole is not the best antenna to compare with, given the orthoganal radiation patterrns one expects between a horizontal dipole and this so-called EH, which is principally a vertical dipole. However, it is notable that an antenna which is only 5% of the size it "should" be (14 inches versus 33 feet, for a 1/2 wave vertical dipole on 20 meters) and yet its radiation is ONLY 9dB down. That is nothing short of remarkable. I have performed measurements on many of the commercially available mobile whips, and at 8 feet long, very few of them are "only" 9dB down. 12dB is more the order of the day. I won't go into the detailed explanation, but for comparison purposes, you can expect the run-of-the-mill, center-loaded whip or trapped dipole to have reduced efficiency, to the tune of 10 log ( (length actual / length full-size)^2). The math is easy to work out - start by predicting the real part of the drive impedance (versus length), then resonate with inductance and add series loss resistance until you're back to 50 ohms. That's how the major manufacturers do it with their various loaded whips. I always look for good ideas. In this case, the idea of using large-diameter conductors in a shortened antenna to overcome the expected extremely high currents is a wonderful idea. The patent itself is irrelevant, so it matters not whether it's valid or not. By the way, in my homebrew foreshortened "fat" dipoles, I have measured efficiencies of about 25% for an antenna which is 10% of "full size", through similar techniques of using fat conductors, but paying more attention to low-loss tuning networks than have been shown so far. N0GV, try building one. Tune it so that the SWR is low, then shove 100W into it. Find out what gets warm, then alter the design (make something fatter) and test again. You will be surprised. Here is the true test of whether you have it tuned "right". You must have all of these conditions satisfied simulataneously: a) SWR is close to 1:1. Don't be happy with 2:1 b) You're measuring at your intended operating frequency c) The antenna is mounted where it's going to be used d) After driving the antenna with a 100W carrier for a full 15 minute, and then touching the antenna within 20 seconds after removing power, NOTHING is warm. If you can satisfy all four criteria at once, then you're turning all your RF into radiation (point source style). This does not prove the EH concept at all, but rather is a validation experiment for any small antenna. If you send RF power to an antenna, it can only go three place - into radiation, heat or reflected back to the transmitter. So, get the latter two items down to zero, and you've got a radiator. But it's a small one, and like any other small one, it's going to be near-isotropic in performance. Best case should be 2.15dB below a free-space dipole. And a free-space dipole is about 6dB BETTER than the average back-yard dipole at 50 feet. AM Reply to a comment by : N0GV on 2002-08-30 Gee --- And I guess that you guys are all impressed with an antenna which admittedly has more than 9 dB of loss as compared with a LOW dipole. (1 1/2 S units is 9 dB). Sure it radiates less but it makes a great space heater! About the lack of EMI -- the earlier poster had it right -- no signal = no EMI. I've read the patent and the theory behind it and it presumes that the E X H = S relationship does not apply for the Poynting vector! Sorry but it just ain't so -- the direction of propagation is normal to both the E and H fields and if either one of them drops to zero then it flat does not radiate! Likewise the Z0 of free space is proportional to the ratio of E(theta) to H(Phi) and we don't even want to begin thinking of rewriting the impedance of free space by increasing the relative permeability or permittivity of free space. Hence the result is pure bunk. On the other hand it is a really interesting way to take a several thousand dollar transciever capable of 100-200 Watts and turn it into a QRP rig! Seems there was an anecdotal story of a South Dakota contact using a dummy load as a radiator in a recent QST..... Please don't believe this garbage about the EH antenna as it is really, really, specious! Grover Larkins and, yes I have a EE degree (three in fact) and, yes I did indeed learn fields and waves from Bob Collin. Reply to a comment by : KD3V on 2002-08-20 !!! LISTEN UP SKEPTICS !!! Please stop making fools of yourselves! If you haven't tried it you have NO BASIS for saying anything! We made one! I used it! it works! I am an electrical engineer. I have been one since 1982. These EH antennas in fact: 1. ... are not "getting something for nothing", 2. they are not "changing the laws of physics in order to make something better than it is", 3. they agree completely with the law of physics that tells us how to get radiation, and for those that have taken the time to read the relevant website, this is called the "Poynting Theorem". This antenna is simple a DIFFERENT method to work this "law of physics". 4. They WORK! I know because I used one! I sent the article to a friend who wanted to make one, he had a friend of his duplicate the 20 meter version that was detailed on the web site. He used it and then I put it up in place on the roof. Simply put, I worked the world on it! I live in Hollywood Calif. From John in South Africa, a 5-7 ... on the LONG path... a FM5 in Martinique, VK's ZL's ZK1, you name it and I only had it for 3 days! So! Read the web sites! These antennas are not using feedline rariation, they are genuine rariators using a different method to create the crossed EM field and as a result they do not need the "linear" distance used by a diplole! These antennas just do it DIFFERENTLY! Yea, i get upset by the "ignorant" who speak up with no basis from which to do so. In the place of facts you put baseless opinion, and in the place of knowledge you put "authority". You are all only making fools of yourselves and those of us who take the time to "find out for ourselves" are the ones who gain real knowledge! We were curious so we built one and we found that it works! Simple. We didn't know until we tried... but we also didn't try to slam it until we KNEW something about which we wanted to speak! I would have posted a few photos but you can already see them when you go read the web site referenced! Ours looked just like theirs do. We used copper plate wrapped around PVC cylinder. Total length.. just like on the website! http://www.qsl.net/w0kph/ This is the link that describes the "full network" verion that our friend built. http://www.qsl.net/w0kph/fullnet.html | ||
| LY3DA | 2002-09-03 | |
|---|---|---|
| Small EH Antenna | ||
| EH antenna is like a ghost. One can believe in it if one want to believe in it. :-) | ||
| N0TONE | 2002-09-03 | |
|---|---|---|
| RE: Small EH Antenna | ||
| N0GV, I am inclined to agree re: the patent claims. However, the patent claims are written with such double-talk (among other consulting activites which I perform, are patent investigations, and the language of this one is terribly difficult to wade through -worse than most). However, I am willing to set that aside for a different discussion, to address the issue of whether this antenna can, in fact, be a viable candidate as a small-profile radiator. In your posting, you acknowledged that the antenna's radiation is 9dB down from a low dipole - and mind, you, the antenna in question was mounted below that low dipole, so the antenna in question, mounted at the same height as the low dipole may have done better. Of course, a dipole is not the best antenna to compare with, given the orthoganal radiation patterrns one expects between a horizontal dipole and this so-called EH, which is principally a vertical dipole. However, it is notable that an antenna which is only 5% of the size it "should" be (14 inches versus 33 feet, for a 1/2 wave vertical dipole on 20 meters) and yet its radiation is ONLY 9dB down. That is nothing short of remarkable. I have performed measurements on many of the commercially available mobile whips, and at 8 feet long, very few of them are "only" 9dB down. 12dB is more the order of the day. I won't go into the detailed explanation, but for comparison purposes, you can expect the run-of-the-mill, center-loaded whip or trapped dipole to have reduced efficiency, to the tune of 10 log ( (length actual / length full-size)^2). The math is easy to work out - start by predicting the real part of the drive impedance (versus length), then resonate with inductance and add series loss resistance until you're back to 50 ohms. That's how the major manufacturers do it with their various loaded whips. I always look for good ideas. In this case, the idea of using large-diameter conductors in a shortened antenna to overcome the expected extremely high currents is a wonderful idea. The patent itself is irrelevant, so it matters not whether it's valid or not. By the way, in my homebrew foreshortened "fat" dipoles, I have measured efficiencies of about 25% for an antenna which is 10% of "full size", through similar techniques of using fat conductors, but paying more attention to low-loss tuning networks than have been shown so far. N0GV, try building one. Tune it so that the SWR is low, then shove 100W into it. Find out what gets warm, then alter the design (make something fatter) and test again. You will be surprised. Here is the true test of whether you have it tuned "right". You must have all of these conditions satisfied simulataneously: a) SWR is close to 1:1. Don't be happy with 2:1 b) You're measuring at your intended operating frequency c) The antenna is mounted where it's going to be used d) After driving the antenna with a 100W carrier for a full 15 minute, and then touching the antenna within 20 seconds after removing power, NOTHING is warm. If you can satisfy all four criteria at once, then you're turning all your RF into radiation (point source style). This does not prove the EH concept at all, but rather is a validation experiment for any small antenna. If you send RF power to an antenna, it can only go three place - into radiation, heat or reflected back to the transmitter. So, get the latter two items down to zero, and you've got a radiator. But it's a small one, and like any other small one, it's going to be near-isotropic in performance. Best case should be 2.15dB below a free-space dipole. And a free-space dipole is about 6dB BETTER than the average back-yard dipole at 50 feet. AM Reply to a comment by : N0GV on 2002-08-30 Gee --- And I guess that you guys are all impressed with an antenna which admittedly has more than 9 dB of loss as compared with a LOW dipole. (1 1/2 S units is 9 dB). Sure it radiates less but it makes a great space heater! About the lack of EMI -- the earlier poster had it right -- no signal = no EMI. I've read the patent and the theory behind it and it presumes that the E X H = S relationship does not apply for the Poynting vector! Sorry but it just ain't so -- the direction of propagation is normal to both the E and H fields and if either one of them drops to zero then it flat does not radiate! Likewise the Z0 of free space is proportional to the ratio of E(theta) to H(Phi) and we don't even want to begin thinking of rewriting the impedance of free space by increasing the relative permeability or permittivity of free space. Hence the result is pure bunk. On the other hand it is a really interesting way to take a several thousand dollar transciever capable of 100-200 Watts and turn it into a QRP rig! Seems there was an anecdotal story of a South Dakota contact using a dummy load as a radiator in a recent QST..... Please don't believe this garbage about the EH antenna as it is really, really, specious! Grover Larkins and, yes I have a EE degree (three in fact) and, yes I did indeed learn fields and waves from Bob Collin. Reply to a comment by : KD3V on 2002-08-20 !!! LISTEN UP SKEPTICS !!! Please stop making fools of yourselves! If you haven't tried it you have NO BASIS for saying anything! We made one! I used it! it works! I am an electrical engineer. I have been one since 1982. These EH antennas in fact: 1. ... are not "getting something for nothing", 2. they are not "changing the laws of physics in order to make something better than it is", 3. they agree completely with the law of physics that tells us how to get radiation, and for those that have taken the time to read the relevant website, this is called the "Poynting Theorem". This antenna is simple a DIFFERENT method to work this "law of physics". 4. They WORK! I know because I used one! I sent the article to a friend who wanted to make one, he had a friend of his duplicate the 20 meter version that was detailed on the web site. He used it and then I put it up in place on the roof. Simply put, I worked the world on it! I live in Hollywood Calif. From John in South Africa, a 5-7 ... on the LONG path... a FM5 in Martinique, VK's ZL's ZK1, you name it and I only had it for 3 days! So! Read the web sites! These antennas are not using feedline rariation, they are genuine rariators using a different method to create the crossed EM field and as a result they do not need the "linear" distance used by a diplole! These antennas just do it DIFFERENTLY! Yea, i get upset by the "ignorant" who speak up with no basis from which to do so. In the place of facts you put baseless opinion, and in the place of knowledge you put "authority". You are all only making fools of yourselves and those of us who take the time to "find out for ourselves" are the ones who gain real knowledge! We were curious so we built one and we found that it works! Simple. We didn't know until we tried... but we also didn't try to slam it until we KNEW something about which we wanted to speak! I would have posted a few photos but you can already see them when you go read the web site referenced! Ours looked just like theirs do. We used copper plate wrapped around PVC cylinder. Total length.. just like on the website! http://www.qsl.net/w0kph/ This is the link that describes the "full network" verion that our friend built. http://www.qsl.net/w0kph/fullnet.html | ||
| W4MQC | 2002-09-02 | |
|---|---|---|
| Small EH Antenna | ||
| The EH antenna does work. Not as good as a resonant antenna, but it does work. I built one for 20 meters in about an hour. Nice little project. Bought everything I needed for the job at Ace Hardware. It is only 18 inches long and so far have worked a ton of stations including PY, EI and UA3 as well as lots of W6's...all with respectable reports. It hangs from a tree limb about 18 feet up and looks like a bird feeder. You can talk all day long about laws of physics and why it doesn't work, but talk is pretty cheap. Build one then talk about it. Until you do that, your position on the matter is a bit weak. I am not going to replace any dipoles with my EH antenna, but it does have merit for either stealth situations or for emergency purposes. Keep the beam, leave the dipoles up...but build an EH antenna and astound your friends...and yourself. de W4MQC | ||
| OK1FOU | 2002-09-02 | |
|---|---|---|
| RE: Small EH Antenna | ||
| Dear DONTHAVEONEYET, the best place for transmitter schematics is ... the internet. Try a search with "transmitter schematic" (or add "ham radio" to make sure it will be for amateur radio). Try to http://come.to/sm0vpo. Or try another one: Just yesterday I built a small CW transmitter for 80 meters with a ceramic resonator. It can be tuned from 3503.6 to 3591.5 with a 15-500 pF variable capacitor. I use it as a test generator only, but according to OK1ACP, the original author, it delivers as much as 100 mW output with only two transistors... If you send me your email address, I'll try to make up some drawing of the schema. Regards, Jindra OK1FOU@centrum.cz Reply to a comment by : DONTHAVEONEYET on 2002-08-30 I'm still debating about it. This doesn't seem like critisism, more like a flame war from the days when I used to frequent slashdot. I stopped going there for this very reason: tired of people trying to shout loud enough to make others think they are right, the other guy is wrong, and that's that. All I'm saying is try it, post your results, then shut up and let someone else talk instead of just flaming from the get-go. Thought most hams were at least mature enough to do that. Side note: anyone know a good place to go for radio schematics? I'm thinking of building my transmitter instead of buying (financial concerns) but I can't seem to find anything online without having to buy a membership somewhere. Reply to a comment by : N0TONE on 2002-08-29 W5LF, yours was a good post, marred by some slight technical errors. First, a dipole antenna is neither electrical nor magnetic in its normal operation. For analysis purposes, programs like NEC focus exclusively on the currents and ignore the voltages. This is only for analytical convenience. NEC makes assumptions about the electric fields generated as a result of the existence of the currents and the associated magnetic fields. It would be just as easy to create software that focused exclusively on the electric voltages appearing on the antenna, and then surmised magnetic properties from them. It would be more correct to say that a dipole antenna creates both electric and magnetic fields, in a ratio appropriate to create a dipole's characteristic far field patterns. Your small loops are known as "magnetic" antennas not becaus they create ONLY a magnetic field, but because the ratio of magnetic to electric field in the near field is predominantly magnetic. As you move away from the small antenna, the fields take on the characteristic ratio of 377 (voltage field / magnetic field) which is true for a plane wave in free space, no matter what kind of radiator produced it. You said, "With a radiation resistance of .01 ohm or less, you get very high voltages (my magnetic loop gives me about 4.7kv on the capacitor at 7 mhz)..." There's a step missing in there. If you feed an antenna with a low radiation resistance at a current node, you get a high current, low voltage situation. If you feed it at a voltage node, you get high voltage and low current. Your capacitor, which you say is experiencing 4.7kV (you did not mention the power at which this occurs) is also experiencing huge currents. For instance, if it's tuned to 200 pF on 20 meters, and really experiencing 4.7kV, then it's also enduring nearly 120 amps. Fact is, super-short antennas have some points that are extremely high current, and some that are extemely high voltage, and some points where there's a bit of both. You're probably coupling into that antenna with a smaller, inner loop. That's because it is so difficult to physically break that loop without incurring resistive loss. The "EH" (I put in quotes because I do not believe there's a new principle involved) antenna, if viewed as a short dipole, is not a magnetic antenna like your loop, but is more appropriately an electric antenna. In the near field, the electric field is large compared to the magnetic field - the ratio is not 377, but much higher. This antenna will also require very low loss matching components. Because it's fed by breaking in the middle, the matching topology is different from your mag loop. I would expect, since it develops a strong electric field and weak magnetic field (in the near field), and most RFI is caused by magnetic coupling, this antenna could very well cause less RFI than a full sized antenna. Again, once you're some distance from the antenna, the radiation becomes planar and the 377 ratio must hold. I have to keep saying it - there's no reason why this antenna cannot work. But we must keep the claims reasonable. The theoretical limit is that it can work as well as a well-built 1/4 wave vertical and no better. A well-built 1/4 wave vertical will have better DX performance than a dipole, unless the dipole is mounted very high. I have read reports from many who've built this antenna, and it seems that nobody with a well-built vertical has built one of these. When they describe their comparison antennas, it seems that there's always a problem in the "reference" antenna. So what they're really finding out is that if they build a small antenna correctly, it can outperform a full-sized antenna built improperly. So - capable of decent performance? Yes. New technology? No. Can it beat a well-built full-sized vertical? No. But few full-sized verticals are built right. AM Reply to a comment by : W5LF on 2002-08-27 Anyone hear of a magnetic loop? 1/4th wavelength or smaller in total diameter, usually they are 1/10th or so. AEA made one, MFJ makes two, German and other companies make them commercially into the thousands of dollars, etc. they work on the same magnetic principle that the CCA, DDA etc magnetic antennas do, the magnetic field of the radio wave and not the electrical. A diapole has both but it was made for the electrical field (but still has its magnetic field). My lawn sprinklers never were bothered with my dipole but came on every time I transmitted with my CFA! (until I put some toroids on its cables). No one is re-writing theory here, no new laws written or old ones discarded. I personally haven't made a network (tuner section) that made me happy with my DDA antenna which stood about 14" high and 4" diameter. However, my 10' circumference loop made from 2" copper pipe (about 3' diameter) using a 15-500pf vacuum variable works wonderfully from 6.5 to 26.5 mhz (too much capacitance for 10 meters). its top performer for 20-15 meters and ok on 40 where its efficiency is down. Don't write anything off until you spend alot of time with it. There are VERY qualified authors and engineers studying and making these. One thing you can't absolutely ever forget, component quality is a absolute requirement with any magnetic antenna. With a radiation resistance of .01 ohm or less, you get very high voltages (my magnetic loop gives me about 4.7kv on the capacitor at 7 mhz) and current. Standard capacitors are out as wiper connections to the rotor (and resistance between plate connections, etc) all have resistive losses, vacuum variables or items such as butterfly capacitors are in, but only if the butterfly caps plates are welded together! See what I mean? Different requirements for this stuff but it can be very fun to mess with. My loop antenna at 10 feet operates as well as my dipole at 30 and the loop has almost no noise. I compare it to a beverage for a low noise floor. Experiment! Ham radio can be fun again if you do. | ||
| KA1OGM | 2002-09-01 | |
|---|---|---|
| RE: Small EH Antenna | ||
| Bill, If the resonant freq is 13.83, it won't work too well on 20m. The best way to tune the coil is to sweep for the highest field strength, and increase turns spacing to go up in frequency. Once the coil is tuned, then the link coupling coil can be adjusted for the impedance match. Jeff KA1OGM Reply to a comment by : AC6IJ on 2002-08-31 After reading all the comments on the EH antenna I deciced to make one see how it performs. The one I made was for 20 meters and I used the 2" PVC pipe with 3" upper and lower cylinders. My coil was made of 15T of #14 house wire and the link was the 2T variety. The antenna was very easy to make and it took about 2 hours to round up the parts and make the antenna. On the initial test the SWR was flat on 13.83 but the RFI was terrible coming back into the radio. I tried ferrite cores on the coax and they helped a little but not much. I tried it along with my cushcraft R-5 and the R-5 made the EH antenna look like a dummy load. No recieve to speak of on the EH and on PSK-31 I could hardly pick up anyone. I guess we have to judge this by our own uses of it and I will continue to try to make the thing hear a little better. I have to admit it is lots of fun working with it. Bill | ||
| AC6IJ | 2002-08-31 | |
|---|---|---|
| Small EH Antenna | ||
| After reading all the comments on the EH antenna I deciced to make one see how it performs. The one I made was for 20 meters and I used the 2" PVC pipe with 3" upper and lower cylinders. My coil was made of 15T of #14 house wire and the link was the 2T variety. The antenna was very easy to make and it took about 2 hours to round up the parts and make the antenna. On the initial test the SWR was flat on 13.83 but the RFI was terrible coming back into the radio. I tried ferrite cores on the coax and they helped a little but not much. I tried it along with my cushcraft R-5 and the R-5 made the EH antenna look like a dummy load. No recieve to speak of on the EH and on PSK-31 I could hardly pick up anyone. I guess we have to judge this by our own uses of it and I will continue to try to make the thing hear a little better. I have to admit it is lots of fun working with it. Bill | ||
| N0GV | 2002-08-30 | |
|---|---|---|
| RE: Small EH Antenna | ||
| Gee --- And I guess that you guys are all impressed with an antenna which admittedly has more than 9 dB of loss as compared with a LOW dipole. (1 1/2 S units is 9 dB). Sure it radiates less but it makes a great space heater! About the lack of EMI -- the earlier poster had it right -- no signal = no EMI. I've read the patent and the theory behind it and it presumes that the E X H = S relationship does not apply for the Poynting vector! Sorry but it just ain't so -- the direction of propagation is normal to both the E and H fields and if either one of them drops to zero then it flat does not radiate! Likewise the Z0 of free space is proportional to the ratio of E(theta) to H(Phi) and we don't even want to begin thinking of rewriting the impedance of free space by increasing the relative permeability or permittivity of free space. Hence the result is pure bunk. On the other hand it is a really interesting way to take a several thousand dollar transciever capable of 100-200 Watts and turn it into a QRP rig! Seems there was an anecdotal story of a South Dakota contact using a dummy load as a radiator in a recent QST..... Please don't believe this garbage about the EH antenna as it is really, really, specious! Grover Larkins and, yes I have a EE degree (three in fact) and, yes I did indeed learn fields and waves from Bob Collin. Reply to a comment by : KD3V on 2002-08-20 !!! LISTEN UP SKEPTICS !!! Please stop making fools of yourselves! If you haven't tried it you have NO BASIS for saying anything! We made one! I used it! it works! I am an electrical engineer. I have been one since 1982. These EH antennas in fact: 1. ... are not "getting something for nothing", 2. they are not "changing the laws of physics in order to make something better than it is", 3. they agree completely with the law of physics that tells us how to get radiation, and for those that have taken the time to read the relevant website, this is called the "Poynting Theorem". This antenna is simple a DIFFERENT method to work this "law of physics". 4. They WORK! I know because I used one! I sent the article to a friend who wanted to make one, he had a friend of his duplicate the 20 meter version that was detailed on the web site. He used it and then I put it up in place on the roof. Simply put, I worked the world on it! I live in Hollywood Calif. From John in South Africa, a 5-7 ... on the LONG path... a FM5 in Martinique, VK's ZL's ZK1, you name it and I only had it for 3 days! So! Read the web sites! These antennas are not using feedline rariation, they are genuine rariators using a different method to create the crossed EM field and as a result they do not need the "linear" distance used by a diplole! These antennas just do it DIFFERENTLY! Yea, i get upset by the "ignorant" who speak up with no basis from which to do so. In the place of facts you put baseless opinion, and in the place of knowledge you put "authority". You are all only making fools of yourselves and those of us who take the time to "find out for ourselves" are the ones who gain real knowledge! We were curious so we built one and we found that it works! Simple. We didn't know until we tried... but we also didn't try to slam it until we KNEW something about which we wanted to speak! I would have posted a few photos but you can already see them when you go read the web site referenced! Ours looked just like theirs do. We used copper plate wrapped around PVC cylinder. Total length.. just like on the website! http://www.qsl.net/w0kph/ This is the link that describes the "full network" verion that our friend built. http://www.qsl.net/w0kph/fullnet.html | ||
| DONTHAVEONEYET | 2002-08-30 | |
|---|---|---|
| RE: Small EH Antenna | ||
| I'm still debating about it. This doesn't seem like critisism, more like a flame war from the days when I used to frequent slashdot. I stopped going there for this very reason: tired of people trying to shout loud enough to make others think they are right, the other guy is wrong, and that's that. All I'm saying is try it, post your results, then shut up and let someone else talk instead of just flaming from the get-go. Thought most hams were at least mature enough to do that. Side note: anyone know a good place to go for radio schematics? I'm thinking of building my transmitter instead of buying (financial concerns) but I can't seem to find anything online without having to buy a membership somewhere. Reply to a comment by : N0TONE on 2002-08-29 W5LF, yours was a good post, marred by some slight technical errors. First, a dipole antenna is neither electrical nor magnetic in its normal operation. For analysis purposes, programs like NEC focus exclusively on the currents and ignore the voltages. This is only for analytical convenience. NEC makes assumptions about the electric fields generated as a result of the existence of the currents and the associated magnetic fields. It would be just as easy to create software that focused exclusively on the electric voltages appearing on the antenna, and then surmised magnetic properties from them. It would be more correct to say that a dipole antenna creates both electric and magnetic fields, in a ratio appropriate to create a dipole's characteristic far field patterns. Your small loops are known as "magnetic" antennas not becaus they create ONLY a magnetic field, but because the ratio of magnetic to electric field in the near field is predominantly magnetic. As you move away from the small antenna, the fields take on the characteristic ratio of 377 (voltage field / magnetic field) which is true for a plane wave in free space, no matter what kind of radiator produced it. You said, "With a radiation resistance of .01 ohm or less, you get very high voltages (my magnetic loop gives me about 4.7kv on the capacitor at 7 mhz)..." There's a step missing in there. If you feed an antenna with a low radiation resistance at a current node, you get a high current, low voltage situation. If you feed it at a voltage node, you get high voltage and low current. Your capacitor, which you say is experiencing 4.7kV (you did not mention the power at which this occurs) is also experiencing huge currents. For instance, if it's tuned to 200 pF on 20 meters, and really experiencing 4.7kV, then it's also enduring nearly 120 amps. Fact is, super-short antennas have some points that are extremely high current, and some that are extemely high voltage, and some points where there's a bit of both. You're probably coupling into that antenna with a smaller, inner loop. That's because it is so difficult to physically break that loop without incurring resistive loss. The "EH" (I put in quotes because I do not believe there's a new principle involved) antenna, if viewed as a short dipole, is not a magnetic antenna like your loop, but is more appropriately an electric antenna. In the near field, the electric field is large compared to the magnetic field - the ratio is not 377, but much higher. This antenna will also require very low loss matching components. Because it's fed by breaking in the middle, the matching topology is different from your mag loop. I would expect, since it develops a strong electric field and weak magnetic field (in the near field), and most RFI is caused by magnetic coupling, this antenna could very well cause less RFI than a full sized antenna. Again, once you're some distance from the antenna, the radiation becomes planar and the 377 ratio must hold. I have to keep saying it - there's no reason why this antenna cannot work. But we must keep the claims reasonable. The theoretical limit is that it can work as well as a well-built 1/4 wave vertical and no better. A well-built 1/4 wave vertical will have better DX performance than a dipole, unless the dipole is mounted very high. I have read reports from many who've built this antenna, and it seems that nobody with a well-built vertical has built one of these. When they describe their comparison antennas, it seems that there's always a problem in the "reference" antenna. So what they're really finding out is that if they build a small antenna correctly, it can outperform a full-sized antenna built improperly. So - capable of decent performance? Yes. New technology? No. Can it beat a well-built full-sized vertical? No. But few full-sized verticals are built right. AM Reply to a comment by : W5LF on 2002-08-27 Anyone hear of a magnetic loop? 1/4th wavelength or smaller in total diameter, usually they are 1/10th or so. AEA made one, MFJ makes two, German and other companies make them commercially into the thousands of dollars, etc. they work on the same magnetic principle that the CCA, DDA etc magnetic antennas do, the magnetic field of the radio wave and not the electrical. A diapole has both but it was made for the electrical field (but still has its magnetic field). My lawn sprinklers never were bothered with my dipole but came on every time I transmitted with my CFA! (until I put some toroids on its cables). No one is re-writing theory here, no new laws written or old ones discarded. I personally haven't made a network (tuner section) that made me happy with my DDA antenna which stood about 14" high and 4" diameter. However, my 10' circumference loop made from 2" copper pipe (about 3' diameter) using a 15-500pf vacuum variable works wonderfully from 6.5 to 26.5 mhz (too much capacitance for 10 meters). its top performer for 20-15 meters and ok on 40 where its efficiency is down. Don't write anything off until you spend alot of time with it. There are VERY qualified authors and engineers studying and making these. One thing you can't absolutely ever forget, component quality is a absolute requirement with any magnetic antenna. With a radiation resistance of .01 ohm or less, you get very high voltages (my magnetic loop gives me about 4.7kv on the capacitor at 7 mhz) and current. Standard capacitors are out as wiper connections to the rotor (and resistance between plate connections, etc) all have resistive losses, vacuum variables or items such as butterfly capacitors are in, but only if the butterfly caps plates are welded together! See what I mean? Different requirements for this stuff but it can be very fun to mess with. My loop antenna at 10 feet operates as well as my dipole at 30 and the loop has almost no noise. I compare it to a beverage for a low noise floor. Experiment! Ham radio can be fun again if you do. | ||
| N0TONE | 2002-08-29 | |
|---|---|---|
| RE: Small EH Antenna | ||
| W5LF, yours was a good post, marred by some slight technical errors. First, a dipole antenna is neither electrical nor magnetic in its normal operation. For analysis purposes, programs like NEC focus exclusively on the currents and ignore the voltages. This is only for analytical convenience. NEC makes assumptions about the electric fields generated as a result of the existence of the currents and the associated magnetic fields. It would be just as easy to create software that focused exclusively on the electric voltages appearing on the antenna, and then surmised magnetic properties from them. It would be more correct to say that a dipole antenna creates both electric and magnetic fields, in a ratio appropriate to create a dipole's characteristic far field patterns. Your small loops are known as "magnetic" antennas not becaus they create ONLY a magnetic field, but because the ratio of magnetic to electric field in the near field is predominantly magnetic. As you move away from the small antenna, the fields take on the characteristic ratio of 377 (voltage field / magnetic field) which is true for a plane wave in free space, no matter what kind of radiator produced it. You said, "With a radiation resistance of .01 ohm or less, you get very high voltages (my magnetic loop gives me about 4.7kv on the capacitor at 7 mhz)..." There's a step missing in there. If you feed an antenna with a low radiation resistance at a current node, you get a high current, low voltage situation. If you feed it at a voltage node, you get high voltage and low current. Your capacitor, which you say is experiencing 4.7kV (you did not mention the power at which this occurs) is also experiencing huge currents. For instance, if it's tuned to 200 pF on 20 meters, and really experiencing 4.7kV, then it's also enduring nearly 120 amps. Fact is, super-short antennas have some points that are extremely high current, and some that are extemely high voltage, and some points where there's a bit of both. You're probably coupling into that antenna with a smaller, inner loop. That's because it is so difficult to physically break that loop without incurring resistive loss. The "EH" (I put in quotes because I do not believe there's a new principle involved) antenna, if viewed as a short dipole, is not a magnetic antenna like your loop, but is more appropriately an electric antenna. In the near field, the electric field is large compared to the magnetic field - the ratio is not 377, but much higher. This antenna will also require very low loss matching components. Because it's fed by breaking in the middle, the matching topology is different from your mag loop. I would expect, since it develops a strong electric field and weak magnetic field (in the near field), and most RFI is caused by magnetic coupling, this antenna could very well cause less RFI than a full sized antenna. Again, once you're some distance from the antenna, the radiation becomes planar and the 377 ratio must hold. I have to keep saying it - there's no reason why this antenna cannot work. But we must keep the claims reasonable. The theoretical limit is that it can work as well as a well-built 1/4 wave vertical and no better. A well-built 1/4 wave vertical will have better DX performance than a dipole, unless the dipole is mounted very high. I have read reports from many who've built this antenna, and it seems that nobody with a well-built vertical has built one of these. When they describe their comparison antennas, it seems that there's always a problem in the "reference" antenna. So what they're really finding out is that if they build a small antenna correctly, it can outperform a full-sized antenna built improperly. So - capable of decent performance? Yes. New technology? No. Can it beat a well-built full-sized vertical? No. But few full-sized verticals are built right. AM Reply to a comment by : W5LF on 2002-08-27 Anyone hear of a magnetic loop? 1/4th wavelength or smaller in total diameter, usually they are 1/10th or so. AEA made one, MFJ makes two, German and other companies make them commercially into the thousands of dollars, etc. they work on the same magnetic principle that the CCA, DDA etc magnetic antennas do, the magnetic field of the radio wave and not the electrical. A diapole has both but it was made for the electrical field (but still has its magnetic field). My lawn sprinklers never were bothered with my dipole but came on every time I transmitted with my CFA! (until I put some toroids on its cables). No one is re-writing theory here, no new laws written or old ones discarded. I personally haven't made a network (tuner section) that made me happy with my DDA antenna which stood about 14" high and 4" diameter. However, my 10' circumference loop made from 2" copper pipe (about 3' diameter) using a 15-500pf vacuum variable works wonderfully from 6.5 to 26.5 mhz (too much capacitance for 10 meters). its top performer for 20-15 meters and ok on 40 where its efficiency is down. Don't write anything off until you spend alot of time with it. There are VERY qualified authors and engineers studying and making these. One thing you can't absolutely ever forget, component quality is a absolute requirement with any magnetic antenna. With a radiation resistance of .01 ohm or less, you get very high voltages (my magnetic loop gives me about 4.7kv on the capacitor at 7 mhz) and current. Standard capacitors are out as wiper connections to the rotor (and resistance between plate connections, etc) all have resistive losses, vacuum variables or items such as butterfly capacitors are in, but only if the butterfly caps plates are welded together! See what I mean? Different requirements for this stuff but it can be very fun to mess with. My loop antenna at 10 feet operates as well as my dipole at 30 and the loop has almost no noise. I compare it to a beverage for a low noise floor. Experiment! Ham radio can be fun again if you do. | ||
| N0TONE | 2002-08-29 | |
|---|---|---|
| RE: Small EH Antenna | ||
| DONTHAVEONEYET, don't give up. If this antenna is genuinely new theory, then it is attracting the proper amount of criticism. The inventors have failed to provide enough data to validate their claims. If they get enough well-written criticisms (you always have to separate that genuinely good questions from the sarcasm in any pursuit), then they will ultimately have to produce proper evidence. At this time, they've not produced a procedure by which one can verify if an antenna is operating in "EH" mode. For instance, one of the inventors posted this: "If the antenna is small, and you are getting good signal reports, then it must be operating as an EH." Clearly, that claim is invalid. I have a few small antennas that work well, but they use traditional dipole or magnetic loop theories. The claim that all small efficient antennas must be working on their new principle is obviously incorrect and will not stand up in a patent claims filing. So, hang in there. Antennas in ham radio have always been the one technical field where black magic appears to reign supreme. The two reasons for that are: 1) The only thing that we're all capable of measuring - SWR - is a useless quantity for predicting antenna performance. However, since we CAN measure it, we do so, and proceed to make claims about antennas based upon it. 2) At HF frequencies, it is literally impossible to properly measure the fields surrounding an antenna unless you're the military and can fly small drone aircraft around in a 5 to 10 miles radius of the antenna, equipped with field measuring devices. Ultimately, in antennas, each ham must determine what his/her goals are, and work to achieve antennas that meet those goals. AM Reply to a comment by : WN3VAW on 2002-08-29 W9WHE, Interesting marketing strategy. Could we refer to this as "The Corbamite Manuever?" Reply to a comment by : W9WHE on 2002-08-27 I have a Corbamite rubber duckie on my HT. The Corbamite coil multiplies whatever power is fed to it by a factor of Ten. Thus, my 5 watt HT has, in effect, a 10 db amplifier, so I can consistently work repeaters 100 miles away (and more) full quieting, with just my 5 watt HT and rubber duckie. Now, I'm making and selling "Small EH antennas" made from Corbamite. With a Corbamite "EH antenna" you will be able to work ZL, VK and RARE DX with only a few milliwatts. Any takers? | ||
| WN3VAW | 2002-08-29 | |
|---|---|---|
| RE: Small EH Antenna | ||
| W9WHE, Interesting marketing strategy. Could we refer to this as "The Corbamite Manuever?" Reply to a comment by : W9WHE on 2002-08-27 I have a Corbamite rubber duckie on my HT. The Corbamite coil multiplies whatever power is fed to it by a factor of Ten. Thus, my 5 watt HT has, in effect, a 10 db amplifier, so I can consistently work repeaters 100 miles away (and more) full quieting, with just my 5 watt HT and rubber duckie. Now, I'm making and selling "Small EH antennas" made from Corbamite. With a Corbamite "EH antenna" you will be able to work ZL, VK and RARE DX with only a few milliwatts. Any takers? | ||
| DONTHAVEONEYET | 2002-08-28 | |
|---|---|---|
| RE: Small EH Antenna -- bogus? | ||
| Take a very good look at my callsign. I don't have one yet, and was seriously considering testing next week to get my license and such. I kept hearing and reading about how hams work with each other, experiment, build and trade ideas and designs. After reading this thread, I'm beginning to reconsider paying my $10 to test if the whole community is like this. Makes me angry to a point seeing people agrue about a friggin antenna design. Instead of complaining about it, design your own instead. If you do, you'll probably get the same response to your idea that this one is getting now. "Thoughts form the universe, not your pen or my sword." - Unknown Reply to a comment by : K1LI on 2002-08-28 It's my recollection from what I learned of Maxwell's equations in college that an electromagnetic field arises when a charge accelerates, the way electrons sinusoidally accelerate on a "Hertzian" antenna. Thus, an electromagnetic field is MORE than the sum of an electric field and a magnetic field, separately generated. It is for this reason that I don't believe the CFA hype. Any physicists out there who can comment? | ||
| K1LI | 2002-08-28 | |
|---|---|---|
| Small EH Antenna -- bogus? | ||
| It's my recollection from what I learned of Maxwell's equations in college that an electromagnetic field arises when a charge accelerates, the way electrons sinusoidally accelerate on a "Hertzian" antenna. Thus, an electromagnetic field is MORE than the sum of an electric field and a magnetic field, separately generated. It is for this reason that I don't believe the CFA hype. Any physicists out there who can comment? | ||
| WB2WIK | 2002-08-28 | |
|---|---|---|
| RE: Small EH Antenna | ||
| W9WHE: The Corbamite antennas sound great. Please send me one dozen of them, I'll pay you via Waitpal. "We the unwilling, led by the unknowing, are doing the impossible for the ungrateful. We've been doing so much with so little for so long, that we're now qualified to do anything with nothing." WB2WIK/6 Reply to a comment by : VK4JAM on 2002-08-28 Hi Bob, I have run simulation for several of the designs presented on the referenced web pages, and have also sent / received an e-mail from Jack W0KPH. Jack has suggested that I “think about the relationship of the fields.... and how a conventional antenna actually radiates.”. Well I have tried this … but I guess I just cannot leave behind all my training / experience in "normal" antenna theory. Please don’t get me wrong – I believe the antenna presented here is great – it’s just that I can not make the leap to a “new” theory at this time. Anyway... I still see the antenna as a fat dipole. The simulations show that making the dipole short does not seem to change the radiation pattern significantly, however there is a need for a good matching network such as that described. I have run simulations using both the public domain NEC software (refer the NEC Archive at http://www.qsl.net/wb6tpu/swindex.html - NEC.XLS by Peter Ward, VK2VCI recommended) and YagiMax (developed by By Lew Gordon, K4VX). The results from both give similar results even though the ways the calculations are performed are a little different. My suggestion is to get the copy of the software and try several simulations. YagiMax is by far the easiest to use. If you send me an e-mail directly I will send you the YagiMax files that Lew sent me. The use of several of the “short fat” dipoles in a Broadside array may prove very interesting. Low cost, simple with a little “punch”. Try the modelling the antenna and you will see what I mean. 73's Andrew Reply to a comment by : W7KWS on 2002-08-24 Andrew, Is there any chance you would be able to share further results from your computer analysis? If so, it would sure be nice to study some field strength numbers at various elevation angles as compared to a reference antenna such as a vertical over good or perfect ground. I presume this antenna is omni directional and, therefore, azimuth readings are all the same. Thanks for sharing your data with us. This is the kind of input we need. 73, Bob, W7KWS Reply to a comment by : VK4JAM on 2002-08-24 The antenna design presented here and on referenced web pages is an interesting design. I do not doubt that it works well. I plan to build one (perhaps with some modification to the matching network). I believe this antenna design is a good compromise for mobile / portable / restricted space applications. Not so sure that I see this as a new design. I see it as a “short fat” dipole, with an interesting matching network. Taking this approach and using NEC or similar computer analysis tools it can be seen that the antenna would produce a gain of around 1.76 dBi. A little down on a normal dipole but not too bad for it’s size. This calculated result does agree with the observations reported by various people who have built the antenna. The theory for the short dipole antenna is presented in many text books. One which I recommend is: Kraus, John D.: “Electromagnetics, Third Edition,” McGraw-Hill Book Company, New York, 1984. Pages 620-633 give a good explanation of the Short Dipole. An interesting design … Yes A new discovery … I don’t think so. 73’s Andrew VK4JAM | ||
| VK4JAM | 2002-08-28 | |
|---|---|---|
| RE: Small EH Antenna | ||
| Hi Bob, I have run simulation for several of the designs presented on the referenced web pages, and have also sent / received an e-mail from Jack W0KPH. Jack has suggested that I “think about the relationship of the fields.... and how a conventional antenna actually radiates.”. Well I have tried this … but I guess I just cannot leave behind all my training / experience in "normal" antenna theory. Please don’t get me wrong – I believe the antenna presented here is great – it’s just that I can not make the leap to a “new” theory at this time. Anyway... I still see the antenna as a fat dipole. The simulations show that making the dipole short does not seem to change the radiation pattern significantly, however there is a need for a good matching network such as that described. I have run simulations using both the public domain NEC software (refer the NEC Archive at http://www.qsl.net/wb6tpu/swindex.html - NEC.XLS by Peter Ward, VK2VCI recommended) and YagiMax (developed by By Lew Gordon, K4VX). The results from both give similar results even though the ways the calculations are performed are a little different. My suggestion is to get the copy of the software and try several simulations. YagiMax is by far the easiest to use. If you send me an e-mail directly I will send you the YagiMax files that Lew sent me. The use of several of the “short fat” dipoles in a Broadside array may prove very interesting. Low cost, simple with a little “punch”. Try the modelling the antenna and you will see what I mean. 73's Andrew Reply to a comment by : W7KWS on 2002-08-24 Andrew, Is there any chance you would be able to share further results from your computer analysis? If so, it would sure be nice to study some field strength numbers at various elevation angles as compared to a reference antenna such as a vertical over good or perfect ground. I presume this antenna is omni directional and, therefore, azimuth readings are all the same. Thanks for sharing your data with us. This is the kind of input we need. 73, Bob, W7KWS Reply to a comment by : VK4JAM on 2002-08-24 The antenna design presented here and on referenced web pages is an interesting design. I do not doubt that it works well. I plan to build one (perhaps with some modification to the matching network). I believe this antenna design is a good compromise for mobile / portable / restricted space applications. Not so sure that I see this as a new design. I see it as a “short fat” dipole, with an interesting matching network. Taking this approach and using NEC or similar computer analysis tools it can be seen that the antenna would produce a gain of around 1.76 dBi. A little down on a normal dipole but not too bad for it’s size. This calculated result does agree with the observations reported by various people who have built the antenna. The theory for the short dipole antenna is presented in many text books. One which I recommend is: Kraus, John D.: “Electromagnetics, Third Edition,” McGraw-Hill Book Company, New York, 1984. Pages 620-633 give a good explanation of the Short Dipole. An interesting design … Yes A new discovery … I don’t think so. 73’s Andrew VK4JAM | ||
| W9WHE | 2002-08-27 | |
|---|---|---|
| Small EH Antenna | ||
| I have a Corbamite rubber duckie on my HT. The Corbamite coil multiplies whatever power is fed to it by a factor of Ten. Thus, my 5 watt HT has, in effect, a 10 db amplifier, so I can consistently work repeaters 100 miles away (and more) full quieting, with just my 5 watt HT and rubber duckie. Now, I'm making and selling "Small EH antennas" made from Corbamite. With a Corbamite "EH antenna" you will be able to work ZL, VK and RARE DX with only a few milliwatts. Any takers? | ||
| W5LF | 2002-08-27 | |
|---|---|---|
| Small EH Antenna | ||
| Anyone hear of a magnetic loop? 1/4th wavelength or smaller in total diameter, usually they are 1/10th or so. AEA made one, MFJ makes two, German and other companies make them commercially into the thousands of dollars, etc. they work on the same magnetic principle that the CCA, DDA etc magnetic antennas do, the magnetic field of the radio wave and not the electrical. A diapole has both but it was made for the electrical field (but still has its magnetic field). My lawn sprinklers never were bothered with my dipole but came on every time I transmitted with my CFA! (until I put some toroids on its cables). No one is re-writing theory here, no new laws written or old ones discarded. I personally haven't made a network (tuner section) that made me happy with my DDA antenna which stood about 14" high and 4" diameter. However, my 10' circumference loop made from 2" copper pipe (about 3' diameter) using a 15-500pf vacuum variable works wonderfully from 6.5 to 26.5 mhz (too much capacitance for 10 meters). its top performer for 20-15 meters and ok on 40 where its efficiency is down. Don't write anything off until you spend alot of time with it. There are VERY qualified authors and engineers studying and making these. One thing you can't absolutely ever forget, component quality is a absolute requirement with any magnetic antenna. With a radiation resistance of .01 ohm or less, you get very high voltages (my magnetic loop gives me about 4.7kv on the capacitor at 7 mhz) and current. Standard capacitors are out as wiper connections to the rotor (and resistance between plate connections, etc) all have resistive losses, vacuum variables or items such as butterfly capacitors are in, but only if the butterfly caps plates are welded together! See what I mean? Different requirements for this stuff but it can be very fun to mess with. My loop antenna at 10 feet operates as well as my dipole at 30 and the loop has almost no noise. I compare it to a beverage for a low noise floor. Experiment! Ham radio can be fun again if you do. | ||
| N0TONE | 2002-08-26 | |
|---|---|---|
| RE: Small EH Antenna | ||
| W7IQ, I am pleased that my luck seems to be better than yours. While I doubt the claims that it works on any different principles than other antennas, I have built several antennas with form factors similar to the antenna described here. And they do work. Do they beat a full-sized antenna? Absolutely not. The best you can hope for with a short antenna is 100% efficiency. The nature of the tradeoffs you are working with are best understood if your efforts are aimed at achieving efficiency, and nothing else. A broadcast engineer noted to me once that when you build an antenna close to full size, you can make a lot of mistakes, and still have an antenna that performs within a few dB of optimum. However, the same error made with a short antenna can render it useless. 12 gauge wire has no place in a short dipole, but is far larger than truly required for a half wave dipole. Similarly, a matching capacitor built from RG-8 may serve well in a gamma match when the antenna element is 1/2 wave long, but if the element is but 5% of a wavelength, then a coaxial cable capacitor should be avoided like the plague. A full-size vertical exhibits gain over a theoretic isotropic radiator. This is becuase the vertical does not have any radiation straight up, instead, that energy is directed horizonatally outward. And, with a 1/4 wave vertical, a certain amount of compression of the horizontal lobe takes place, which means more of the radiated power heads toward the horizon than one might otherwise expect, and we achieve "gain". Of course, NO antenna provides amplification. Gain is purely a result of the antenna directing LESS energy in some directions, and favoring other directions. From that description comes the expected results of this small antenna. Any antenna which is a small percentage of a wavelength long approaches the performance of an ideal isotropic radiator. I don't know that this antenna has any radiation straight up, but it is certain that its main horizontal lobe is wider than one produced by a 1/4 wave vertical. Therefore, even at 100% efficiency, one can expect the radiation at some elevation angles to be a few dB below that of a full sized vertical. The radiation at other angles (which may or may not be useful angles), however, may be higher. Andrew descrbibes this antenna as a physically short fat dipole, and that's probably a good way to view it. With this model in mind, NEC would predict the feedpoint impedance to be a very small resistance in series with a large capacitive reactance. Your matching network needs to tune out the capacitance and transform to close to 50 ohms. Once the capacitance has been nulled out, you will have extremely high currents at the antenna feedpoint. It only takes a few tenths of an ohm of resistance to have a major on the performance of such an antenna. One of the short fat dipoles which I constructed gave me disappointing results. I then applied the CW test. I fed it with 100 watts of RF for a few minutes, then disconnected the transmitter, and checked to see what got warm. My 8 gauge wires which led to the two cylinders were just warm to the touch. I had no idea if that meant they were dissipating two watts or 90 watts, though. I replaced the 8 gauge wires with 1/2" soft-drawn copper. Without changing my tuning network, I immediately was greeted with stronger received signals, and was able to make some QSOs. The reduction in loss in the feed system actually caused a change in the feedpoint impedance, and once I re-tuned the matching network, I even got better results. For local QSOs (less than 200 miles on 80 meters), my short fat vertical dipole provides better results than my 1/4 wave vertical. For anything further than 500 miles, the 1/4 wave vertical is superior. But, you can believe this antenna to be deaf very easily, as it is extremely narrowband compared to anything full size. If tuned for 3830 kHz, for instance (the frequency of many local contest club nets), I am utterly unable to hear anything on 3905, where there's a traffic net. I must retune the matching network. That is one litmus test of a small antenna's efficiency. If it's efficient, and you're using LC matching, then it WILL be narrow. Anybody who's used a low frequency hamstik on their car has experienced this particular phenomenon. I agree with several others. A good design, yes, if you keep your conductor diameters large. A new mode of antenna? No. AM Reply to a comment by : W7IQ on 2002-08-25 Let me inject a bit of my logic here. With my luck in building all things electrical, I can assure you that this antenna is NOT going to work! | ||
| WX4O | 2002-08-25 | |
|---|---|---|
| RE: Small EH Antenna | ||
| I agree about the range testing. I have an 80 mtr. Isotron and it seems to work pretty well for a small antenna. It appears to me that it is a different version of the same pricipal. John Reply to a comment by : KA0HCP on 2002-08-25 -Anything will work as an antenna, even a light bulb. And, if it meets your needs, then it is an adequate antenna. -These so-called EH antennas are nothing earthshaking, nor particularly efficient. After reviewing all the claims and comments and "theory", I think that they are vertical dipoles with really wide elements, similar to an Isotron or MFJ antenna. The EH theory claims are bogus, I wish they were true. -Performance is not great, but it works. The basic 20M 2.5 inch diameter antenna appears to be about 6dB below my tuned 20M Hygain Vertical (mounted inside the stairwell of my appartment). And note, that it was usually 2-3 dB below a tuned 20M Bazooka Dipole when I had an antenna farm outside. -Regarding the comment above "noise level is absent"...no kidding, it is a really deaf antenna. -Re: "no EMI"... bull, this thing lit up my shack like nothing I've ever seen in 22+ years. The later versions with the two internal isolation coils may help prevent this, and I plan to experiment with these modifications. I had to use a Radio Works Line Isolator just to make the antenna useable. BTW, this antenna radiates down the line like mad, and made it nearly impossible to get a reliable SWR reading. -Nonetheless, I am forced to live in an apartment for the moment and need an antenna that will work 40M/and Civil Air Patrol 4.585 Mhz. I plan to build the full 4.5 inch diameter version with the internal coils as soon as I can get my hands on some copper foil. *** Will someone please test this on an antenna range and settle the arguments???*** 73, Bill | ||
| KA1OGM | 2002-08-25 | |
|---|---|---|
| RE: Small EH Antenna | ||
| Bill, Consider using aluminum roof flashing for the plates. This stuff is available at any Home Depot at very reasonable prices, and comes in rolls anywhere from 6" to 20" wide. Two of the round "Quaker Oats" boxes makes a great form for the 40m, since they are exactly 4" in diameter. Coil efficiency is best with bare solid copper wire or soft copper tubing, but doesn't suffer too much if you use white insulated solid copper instead. Colored insulation, especially black, affects coil efficiency because of carbon in the coloring. The same is even more important with PVC pipe used for the forms (don't use the black stuff, or the grey electrical conduit stuff). Spacing coils at one diameter will tend to be better than tightly winding coils with no spacing. The test of efficiency for coils on these antennas is to pump some power into them for a few minutes, then see if anything gets warm. Simple two cylinder plus coil and link coupler style antennas can be made that do not evidence any slightest heating with full legal output, but you'll never know if the thing really has that level of efficiency if you don't do the "smoke test". The chances are that any disappointments people have with these will most likely show heat with only 50 or 100 watts CW after a couple of minutes. Jeff Barnard KA1OGM Reply to a comment by : KA0HCP on 2002-08-25 -Anything will work as an antenna, even a light bulb. And, if it meets your needs, then it is an adequate antenna. -These so-called EH antennas are nothing earthshaking, nor particularly efficient. After reviewing all the claims and comments and "theory", I think that they are vertical dipoles with really wide elements, similar to an Isotron or MFJ antenna. The EH theory claims are bogus, I wish they were true. -Performance is not great, but it works. The basic 20M 2.5 inch diameter antenna appears to be about 6dB below my tuned 20M Hygain Vertical (mounted inside the stairwell of my appartment). And note, that it was usually 2-3 dB below a tuned 20M Bazooka Dipole when I had an antenna farm outside. -Regarding the comment above "noise level is absent"...no kidding, it is a really deaf antenna. -Re: "no EMI"... bull, this thing lit up my shack like nothing I've ever seen in 22+ years. The later versions with the two internal isolation coils may help prevent this, and I plan to experiment with these modifications. I had to use a Radio Works Line Isolator just to make the antenna useable. BTW, this antenna radiates down the line like mad, and made it nearly impossible to get a reliable SWR reading. -Nonetheless, I am forced to live in an apartment for the moment and need an antenna that will work 40M/and Civil Air Patrol 4.585 Mhz. I plan to build the full 4.5 inch diameter version with the internal coils as soon as I can get my hands on some copper foil. *** Will someone please test this on an antenna range and settle the arguments???*** 73, Bill | ||
| KA0HCP | 2002-08-25 | |
|---|---|---|
| Small EH Antenna | ||
| -Anything will work as an antenna, even a light bulb. And, if it meets your needs, then it is an adequate antenna. -These so-called EH antennas are nothing earthshaking, nor particularly efficient. After reviewing all the claims and comments and "theory", I think that they are vertical dipoles with really wide elements, similar to an Isotron or MFJ antenna. The EH theory claims are bogus, I wish they were true. -Performance is not great, but it works. The basic 20M 2.5 inch diameter antenna appears to be about 6dB below my tuned 20M Hygain Vertical (mounted inside the stairwell of my appartment). And note, that it was usually 2-3 dB below a tuned 20M Bazooka Dipole when I had an antenna farm outside. -Regarding the comment above "noise level is absent"...no kidding, it is a really deaf antenna. -Re: "no EMI"... bull, this thing lit up my shack like nothing I've ever seen in 22+ years. The later versions with the two internal isolation coils may help prevent this, and I plan to experiment with these modifications. I had to use a Radio Works Line Isolator just to make the antenna useable. BTW, this antenna radiates down the line like mad, and made it nearly impossible to get a reliable SWR reading. -Nonetheless, I am forced to live in an apartment for the moment and need an antenna that will work 40M/and Civil Air Patrol 4.585 Mhz. I plan to build the full 4.5 inch diameter version with the internal coils as soon as I can get my hands on some copper foil. *** Will someone please test this on an antenna range and settle the arguments???*** 73, Bill | ||
| W7IQ | 2002-08-25 | |
|---|---|---|
| Small EH Antenna | ||
| Let me inject a bit of my logic here. With my luck in building all things electrical, I can assure you that this antenna is NOT going to work! | ||
| W7KWS | 2002-08-24 | |
|---|---|---|
| RE: Small EH Antenna | ||
| Andrew, Is there any chance you would be able to share further results from your computer analysis? If so, it would sure be nice to study some field strength numbers at various elevation angles as compared to a reference antenna such as a vertical over good or perfect ground. I presume this antenna is omni directional and, therefore, azimuth readings are all the same. Thanks for sharing your data with us. This is the kind of input we need. 73, Bob, W7KWS Reply to a comment by : VK4JAM on 2002-08-24 The antenna design presented here and on referenced web pages is an interesting design. I do not doubt that it works well. I plan to build one (perhaps with some modification to the matching network). I believe this antenna design is a good compromise for mobile / portable / restricted space applications. Not so sure that I see this as a new design. I see it as a “short fat” dipole, with an interesting matching network. Taking this approach and using NEC or similar computer analysis tools it can be seen that the antenna would produce a gain of around 1.76 dBi. A little down on a normal dipole but not too bad for it’s size. This calculated result does agree with the observations reported by various people who have built the antenna. The theory for the short dipole antenna is presented in many text books. One which I recommend is: Kraus, John D.: “Electromagnetics, Third Edition,” McGraw-Hill Book Company, New York, 1984. Pages 620-633 give a good explanation of the Short Dipole. An interesting design … Yes A new discovery … I don’t think so. 73’s Andrew VK4JAM | ||
| VK4JAM | 2002-08-24 | |
|---|---|---|
| Small EH Antenna | ||
| The antenna design presented here and on referenced web pages is an interesting design. I do not doubt that it works well. I plan to build one (perhaps with some modification to the matching network). I believe this antenna design is a good compromise for mobile / portable / restricted space applications. Not so sure that I see this as a new design. I see it as a “short fat” dipole, with an interesting matching network. Taking this approach and using NEC or similar computer analysis tools it can be seen that the antenna would produce a gain of around 1.76 dBi. A little down on a normal dipole but not too bad for it’s size. This calculated result does agree with the observations reported by various people who have built the antenna. The theory for the short dipole antenna is presented in many text books. One which I recommend is: Kraus, John D.: “Electromagnetics, Third Edition,” McGraw-Hill Book Company, New York, 1984. Pages 620-633 give a good explanation of the Short Dipole. An interesting design … Yes A new discovery … I don’t think so. 73’s Andrew VK4JAM | ||
| OK1FOU | 2002-08-24 | |
|---|---|---|
| Small EH Antenna | ||
| Hi folks, I have always had "antenna placement problem", so CFA and EH was an interesting option to experiment with. I tried to build a CFA, with the kind suppoort of W0KPH. Unfortunately, I was unable to tune it properly. It was possible to hear something on it, but transmission was basically impossible. When I looked closer into the "matching network", I was sure it could be matched to 1:1 SWR, but only as a result of perfect match to the matching network's own loss impedance. When perfect 1:1 match occurred, all signals from the band disappeared. The nmatching network was one of the recommended ones. This kind'a device reminds me of perpetuum mobile. Later I tried a EH. I think that this one, being a quite open resonating circuit, might actually radiate some power, but I was not successful to tune mine into the band. It was far too sensitive to anything in the surrounding environment. At least it does not work in limited space. I can understand that EH might need something like 0.75-1.5 lambda free space around it. Or maybe, to the contrary, it works fine as a resonant driver if a metallic structure is nearby. My practical test & my 2 cents. 73 Jindra OK1FOU, OM9AMU | ||
| N0TONE | 2002-08-23 | |
|---|---|---|
| RE: Small EH Antenna | ||
| When comparing two antennas, keep things as close to the same as you can. In brass terms, don't compare the EH against a dipole. The EH, as proposed, exhibits properties of a vertical radiator. EG, if you can keep the losses down, you will generate more low angle radiation than a horizontal antenna. So, please do not compare against a Yagi - they are different animals. The original posting included clues to this effect. It claims the antenna is close to 100% efficient, but then confesses that its performance is fully 1 to 2 S-units down, which places it a lot closer to 10%, than 100%. But that's assuming the radiation angles are the same between his dipole and the EH, which they're probably not. So far, the comparisons people have made between the EH and other vertical radiators support a contention that the EH is merely a small, compromise antenna, with some thought given to reducing the losses. It could do a lot worse, but it IS a compromise antenna. Anybody who's put thought into how to minimize losses in a short dipole has built antennas with fat radiators like the EH. I have several myself. My thought - copy it, but don't try to explain its operation on a "new" principal. The actual behavior of the antennas as others have describe them are perfectly in accordance with predictions from any of the modelling software packages that claim to model "ordinary" antennas. This is a well-thought out small antenna, not a new concept. AM Reply to a comment by : WB2WIK on 2002-08-23 I haven't built one. KD3V says he has, and is in Hollywood, which is close to me. So, I think the path of least resistance would be for KD3V to bring his EH antenna to my house, where we can try it, empirically, against other antennas, and accurately measure the results. KD3V, are you up for this? Then, he and I live close enough that when working almost anywhere, we'd be the same distance to the test station; so, we could each be "home" and run virtually the same experiment. Antenna efficiency has very little to do with performance. All power delivered to an antenna must be either radiated, reflected or converted to heat, light, sound or motion. Since I don't have any antennas that convert energy to light, sound or motion, I'll bet it's radiated, reflected, or converted to heat in virtually every antenna there is. If the power is all radiated, it's a 100% efficient antenna. I can get a paper clip to do that, with a small matching network. The initial RFI problems discussed in the article are likely more the result of poor antenna placement than anything else. Of course low antennas placed close to the home will couple to more appliances prone to reception of interference than nice high, elevated ones will. Such is the inevitable drawback of most "stealth" installations -- you may not see them, but they'll find your electronic appliances, and often times, those of the neighbors, as well. I'm up for the "EH comparison," any time. Let's set it up. WB2WIK/6 Reply to a comment by : K3PZ on 2002-08-23 This topic was recently discussed on QRZ.com and drew alot of the same scepticism, controversy and nasty comments no doubt by the same people as here. The human ego can be a very vengeful creature. Having "a mind that is open to everything but attached to nothing" is what has allowed man to become the superior beings that we are today. Paul Zora K3PZ Myrtle Beach | ||
| WB2WIK | 2002-08-23 | |
|---|---|---|
| RE: Small EH Antenna | ||
| I haven't built one. KD3V says he has, and is in Hollywood, which is close to me. So, I think the path of least resistance would be for KD3V to bring his EH antenna to my house, where we can try it, empirically, against other antennas, and accurately measure the results. KD3V, are you up for this? Then, he and I live close enough that when working almost anywhere, we'd be the same distance to the test station; so, we could each be "home" and run virtually the same experiment. Antenna efficiency has very little to do with performance. All power delivered to an antenna must be either radiated, reflected or converted to heat, light, sound or motion. Since I don't have any antennas that convert energy to light, sound or motion, I'll bet it's radiated, reflected, or converted to heat in virtually every antenna there is. If the power is all radiated, it's a 100% efficient antenna. I can get a paper clip to do that, with a small matching network. The initial RFI problems discussed in the article are likely more the result of poor antenna placement than anything else. Of course low antennas placed close to the home will couple to more appliances prone to reception of interference than nice high, elevated ones will. Such is the inevitable drawback of most "stealth" installations -- you may not see them, but they'll find your electronic appliances, and often times, those of the neighbors, as well. I'm up for the "EH comparison," any time. Let's set it up. WB2WIK/6 Reply to a comment by : K3PZ on 2002-08-23 This topic was recently discussed on QRZ.com and drew alot of the same scepticism, controversy and nasty comments no doubt by the same people as here. The human ego can be a very vengeful creature. Having "a mind that is open to everything but attached to nothing" is what has allowed man to become the superior beings that we are today. Paul Zora K3PZ Myrtle Beach | ||
| K3PZ | 2002-08-23 | |
|---|---|---|
| Small EH Antenna | ||
| This topic was recently discussed on QRZ.com and drew alot of the same scepticism, controversy and nasty comments no doubt by the same people as here. The human ego can be a very vengeful creature. Having "a mind that is open to everything but attached to nothing" is what has allowed man to become the superior beings that we are today. Paul Zora K3PZ Myrtle Beach | ||
| KD7PKO | 2002-08-22 | |
|---|---|---|
| Small EH Antenna | ||
| GE Just a couple of thoughts come to mind for me about this antenna: 1)Ham radio is about experimenting right? So if I can experiment with something that will only set me back five bucks, I'm all for it! It kills me to consider my $800.00 radio works best on ten bucks worth of wire and some ceramic insulators hi. hi. So why not try it on free tin foil and cardboard? I hate instant karma...... 2) To those who blow off "new ideas" keep this thought in mind: "Why do people with closed minds always have an open mouth?" I saw this on a bumper sticker and will always remember it?!?!? BTW, whenever I have more than a couple of thoughts in mind, I always get a headache! Must be my limited mind. Naw, it's the chronic RF exposure!!! 73 and happy tinkering! Chris-KD7PKO | ||
| W7KWS | 2002-08-22 | |
|---|---|---|
| RE: Small EH Antenna | ||
| John, Nice bit of information. I've built several tuned loops for 30 through 10 meters and they've worked very well. I've never done any analysis on them, but I've taken stock in the numbers published in the more credible references and they've compared to dipoles favorably. I don’t know how this squares with your thoughts, but I don’t use multiple loops, just a single turn with a high voltage capacitor at the bottom of the loop, as shown in the Antenna Handbook. This capacitor needs to be high voltage as the high Q and the power levels make for a very high voltage at this location. The loop is around two and a half feet in diameter and is made of 1” copper water pipe, soldered at all joints. This loop is very low impedance and the handbook shows a stub kind of feed. I took an idea from MFJ’s loop and feed a small exciter loop (about 10” Diameter) instead of using the stub approach. This small loop is situated inside the larger loop and in the same plane. This makes the feed VERY easy. I make my own split stator capacitors as per the post by Notone, but I use Teflon tubing for a dielectric for lower losses and a higher stand off voltage. Teflon is about 1000 volts per mil. of thickness, if my memory serves me correctly. This arrangement takes a KW +++ with out any perceived heat build up and tunes 14 MHz to 30 MHz. very nicely. Thanks for the input, it is appreciated. 73, Bob Reply to a comment by : W3JJH on 2002-08-22 Bob: You're correct that the relationship between the length of a conductor and its efficency as an antenna is not linear. However, for systems which are small compared to a wavelength, a linear relationship holds. Loop antenna work by having multiple turns of wire in the field. The potential across the terminals of a loop which is small compared to a wavelength is E = k*f*N*S*B, where k is a fudge factor depending on the core material (if any), f is the signal frequency, N is the number of turns, S is the cross sectional area of the loop, and B is the field strength. More turns will give a stronger signal. So will a larger loop. As the dimensions a radiator begin to exceed roughly 0.1 wavelength, its radiation impedance is defined by a rather inconvenient relationship with its geometry. As the size of the radiator becomes small, the impedance of the antenna becomes a poor match to the impedance of free space. As the size approaches zero, the SWR at the interface between the antenna and the medium becomes infinite, and no power can be radiated. The impedance at the input to the antenna may give a perfect match to the transmitter, but, if that is so, all the power will be burned in the antenna. None of this means that one can't communicate using small antennas. I've done it. I use a compact antenna with my backpacking QRP rig, working all over the world with an FT-817 and an Outbacker. But, even when I'm camping, I'll put up as much wire as I can when I have the time and space. 73 de W3JJH (John, I go by my middle name) Reply to a comment by : W7KWS on 2002-08-21 William (W3JJH), The problem that I see with your ideas about size of an antenna relating to its efficiency is that, while size is a factor, it is not the only factor involved. Your comparison of an isotropic source to a dipole suggests that a dipole radiates more energy than the point source. The fact is that it does not. Except for heat conversion in the resistance of both antennas and assuming for the moment that there are equal or no feed line losses, both antennas radiate exactly the same amount of energy, regardless of size. The differences you describe are due to the directional nature of the dipole versus the fact that the isotropic antenna distributes its energy equally in all directions, therefore, no one direction benefits over another, as is the case with the dipole. Regarding wire length versus antenna efficiency, I quote from my copy of the 5th edition of the Reference Data for Radio Engineers, page 25-7; “In addition, antenna efficiencies vary from about 70 percent for a 0.15-wavelength physical height to over 95 percent for a 0.6 wavelength height. This is for a vertical, and doesn’t account for why a loop can be above 90 percent, but it does show that a very short antenna of 0.15 wavelength can still radiate with more efficiency than one would suspect from a linear formula such as you proposed in your previous post. Make no mistake, I doubt that the EH Antenna works very well, but I know that the tuned loop does. And, it is a small antenna. In facts, it can be a small fraction of a wavelength and approach the efficiency of a dipole. This is because factors other than size are involved. If you can get a copy of any ARRL Antenna book and read about it, you will see that it is true. Also, you no longer need an extensive antenna range to determine the value of an antenna. There are many very good computer modeling programs that produce results that are very close to what you would find on an antenna range. Believe it or not, we only think we have a handle on physics. People are proving every day that even Einstein didn’t have it all right. THERE ARE NEW THINGS TO DISCOVER ALL THE TIME. Even the fact that a small antenna like the tuned loop can work very well compared with much larger antennas. Whether the EH Antenna is a good one is a simple matter of analysis. I wish I had those analytical skills myself, but I don’t, so I rely on the published references of those that do have the skills. The loop has been studied for years and has been proven to work. Maybe we can attract someone to this discussion that can do a computer model of the EH antenna and give us some real data that we can rely on. 73, Bob Reply to a comment by : W3JJH on 2002-08-21 I don't have a copy of the reference which W3KWS cites, but please allow me to make some further comments. The "mechanics" of wave propagation are well known and have been rigorously descirbed for about 150 years now. Most electrical engineering students take a course in Fields & Waves during their junior or senior year. In that course they learn that small radiators approximate a point source; such antennas have omnidirectional patterns and radiate equally poorly in all directions. Large radiators are more efficient, but are also more directive. For example, a half-wave dipole works well to the sides, but is deaf and dumb off the ends. Extremely large radiators generally do not work well because of phasing problems with the signals coming from different points on the antenna. Note that a small antenna that has an efficiency many dB lower than a dipole may hear a signal coming from a bearing off the end of the dipole better than the larger antenna. As an analogy, consider a set of loudspeakers. It is possible to construct two different loudspeakers systems which have the same low frequency cutoff using different size drivers and enclosures. Let's say we want a 20-Hz low end cutoff, and we build one system with a 38-cm (15-in) driver in a 600-l (21 cu ft) enclosure. The system efficiency will be roughly 1 %. If we build the other system with a 11-cm (4-1/2-in) driver in a 30-l (1.1 cu ft) box, the system efficiency will be around 0.05 %. At low frequencies we'll be able to get the same sound level out of the second system only if we use 20X the amplifier power. However, the smaller system will do a better job of reproducing signals above 1-kHz; the bigger woofer becomes an extremely large radiator at these frequencies. This is why a proper audio system has a woofer and a tweeter (at least!). Similarly, we shouldn't use a 2-m ground plane on 80-m or an 80-m vertical on 2-m. HF antenna testing requires large, open spaces and calibrated test gear which most of us do not possess. Even some manufacturers of HF antennas do not have a proper antenna test range. I take all antenna performance claims with a grain of salt until I have verified that test data actually exists and was properly measured. I live on a small city lot. I can just fit a 70-ft dipole with loading inductors on my site. Fed with ladder line, it works sorta OK on all the bands from 160 through 10. I also have an Outbacker on an Alpha-Delta stand. In some cases (depending on the bearing to the other station or signal vertical arrival angle) it works better than the dipole. But, except on the 12- and 10-m bands, it is a less efficent radiator than the dipole. Reply to a comment by : W7KWS on 2002-08-20 In using wire length as a linear indicator of signal capture/radiation efficiency (presumed law of physics in previous post), how do you account for the fact that a tuned magnetic loop antenna, at 8.5 Ft. in circumference, is only down 1.0 dB below a "large antenna" for the same band? Reference the ARRL Antenna Handbook, 16th edition, page 5-13, loop design No. 5. Good wishes to all in hopes we all learn here. 73, Bob, W7KWS Reply to a comment by : W3JJH on 2002-08-20 I'm open-minded, but not so open-minded that my brain has fallen out. 1. My dummy load has a 1.1:1 SWR on 20-m. It doesn't radiate very well. 2. At 6 dB/S-unit, a drop of 1-1/2 S-units represents a 90-% power loss. If the signals coming in the side of my dipole were only 9 dB above those from a small "EH" antenna, I would start checking for loose or corroded connections on the dipole. The current in a wire in an H-field is proportional to the strength of field times the length of the wire. Use a shorter wire, get a smaller signal. The potential on a conductive surface in an E-field is proportional to the strength of the field times the size of the surface. Use a smaller area, get a smaller signal. Scotty is right: "Ye canna change the laws of physics!." | ||
| W3JJH | 2002-08-22 | |
|---|---|---|
| RE: Small EH Antenna | ||
| Bob: You're correct that the relationship between the length of a conductor and its efficency as an antenna is not linear. However, for systems which are small compared to a wavelength, a linear relationship holds. Loop antenna work by having multiple turns of wire in the field. The potential across the terminals of a loop which is small compared to a wavelength is E = k*f*N*S*B, where k is a fudge factor depending on the core material (if any), f is the signal frequency, N is the number of turns, S is the cross sectional area of the loop, and B is the field strength. More turns will give a stronger signal. So will a larger loop. As the dimensions a radiator begin to exceed roughly 0.1 wavelength, its radiation impedance is defined by a rather inconvenient relationship with its geometry. As the size of the radiator becomes small, the impedance of the antenna becomes a poor match to the impedance of free space. As the size approaches zero, the SWR at the interface between the antenna and the medium becomes infinite, and no power can be radiated. The impedance at the input to the antenna may give a perfect match to the transmitter, but, if that is so, all the power will be burned in the antenna. None of this means that one can't communicate using small antennas. I've done it. I use a compact antenna with my backpacking QRP rig, working all over the world with an FT-817 and an Outbacker. But, even when I'm camping, I'll put up as much wire as I can when I have the time and space. 73 de W3JJH (John, I go by my middle name) Reply to a comment by : W7KWS on 2002-08-21 William (W3JJH), The problem that I see with your ideas about size of an antenna relating to its efficiency is that, while size is a factor, it is not the only factor involved. Your comparison of an isotropic source to a dipole suggests that a dipole radiates more energy than the point source. The fact is that it does not. Except for heat conversion in the resistance of both antennas and assuming for the moment that there are equal or no feed line losses, both antennas radiate exactly the same amount of energy, regardless of size. The differences you describe are due to the directional nature of the dipole versus the fact that the isotropic antenna distributes its energy equally in all directions, therefore, no one direction benefits over another, as is the case with the dipole. Regarding wire length versus antenna efficiency, I quote from my copy of the 5th edition of the Reference Data for Radio Engineers, page 25-7; “In addition, antenna efficiencies vary from about 70 percent for a 0.15-wavelength physical height to over 95 percent for a 0.6 wavelength height. This is for a vertical, and doesn’t account for why a loop can be above 90 percent, but it does show that a very short antenna of 0.15 wavelength can still radiate with more efficiency than one would suspect from a linear formula such as you proposed in your previous post. Make no mistake, I doubt that the EH Antenna works very well, but I know that the tuned loop does. And, it is a small antenna. In facts, it can be a small fraction of a wavelength and approach the efficiency of a dipole. This is because factors other than size are involved. If you can get a copy of any ARRL Antenna book and read about it, you will see that it is true. Also, you no longer need an extensive antenna range to determine the value of an antenna. There are many very good computer modeling programs that produce results that are very close to what you would find on an antenna range. Believe it or not, we only think we have a handle on physics. People are proving every day that even Einstein didn’t have it all right. THERE ARE NEW THINGS TO DISCOVER ALL THE TIME. Even the fact that a small antenna like the tuned loop can work very well compared with much larger antennas. Whether the EH Antenna is a good one is a simple matter of analysis. I wish I had those analytical skills myself, but I don’t, so I rely on the published references of those that do have the skills. The loop has been studied for years and has been proven to work. Maybe we can attract someone to this discussion that can do a computer model of the EH antenna and give us some real data that we can rely on. 73, Bob Reply to a comment by : W3JJH on 2002-08-21 I don't have a copy of the reference which W3KWS cites, but please allow me to make some further comments. The "mechanics" of wave propagation are well known and have been rigorously descirbed for about 150 years now. Most electrical engineering students take a course in Fields & Waves during their junior or senior year. In that course they learn that small radiators approximate a point source; such antennas have omnidirectional patterns and radiate equally poorly in all directions. Large radiators are more efficient, but are also more directive. For example, a half-wave dipole works well to the sides, but is deaf and dumb off the ends. Extremely large radiators generally do not work well because of phasing problems with the signals coming from different points on the antenna. Note that a small antenna that has an efficiency many dB lower than a dipole may hear a signal coming from a bearing off the end of the dipole better than the larger antenna. As an analogy, consider a set of loudspeakers. It is possible to construct two different loudspeakers systems which have the same low frequency cutoff using different size drivers and enclosures. Let's say we want a 20-Hz low end cutoff, and we build one system with a 38-cm (15-in) driver in a 600-l (21 cu ft) enclosure. The system efficiency will be roughly 1 %. If we build the other system with a 11-cm (4-1/2-in) driver in a 30-l (1.1 cu ft) box, the system efficiency will be around 0.05 %. At low frequencies we'll be able to get the same sound level out of the second system only if we use 20X the amplifier power. However, the smaller system will do a better job of reproducing signals above 1-kHz; the bigger woofer becomes an extremely large radiator at these frequencies. This is why a proper audio system has a woofer and a tweeter (at least!). Similarly, we shouldn't use a 2-m ground plane on 80-m or an 80-m vertical on 2-m. HF antenna testing requires large, open spaces and calibrated test gear which most of us do not possess. Even some manufacturers of HF antennas do not have a proper antenna test range. I take all antenna performance claims with a grain of salt until I have verified that test data actually exists and was properly measured. I live on a small city lot. I can just fit a 70-ft dipole with loading inductors on my site. Fed with ladder line, it works sorta OK on all the bands from 160 through 10. I also have an Outbacker on an Alpha-Delta stand. In some cases (depending on the bearing to the other station or signal vertical arrival angle) it works better than the dipole. But, except on the 12- and 10-m bands, it is a less efficent radiator than the dipole. Reply to a comment by : W7KWS on 2002-08-20 In using wire length as a linear indicator of signal capture/radiation efficiency (presumed law of physics in previous post), how do you account for the fact that a tuned magnetic loop antenna, at 8.5 Ft. in circumference, is only down 1.0 dB below a "large antenna" for the same band? Reference the ARRL Antenna Handbook, 16th edition, page 5-13, loop design No. 5. Good wishes to all in hopes we all learn here. 73, Bob, W7KWS Reply to a comment by : W3JJH on 2002-08-20 I'm open-minded, but not so open-minded that my brain has fallen out. 1. My dummy load has a 1.1:1 SWR on 20-m. It doesn't radiate very well. 2. At 6 dB/S-unit, a drop of 1-1/2 S-units represents a 90-% power loss. If the signals coming in the side of my dipole were only 9 dB above those from a small "EH" antenna, I would start checking for loose or corroded connections on the dipole. The current in a wire in an H-field is proportional to the strength of field times the length of the wire. Use a shorter wire, get a smaller signal. The potential on a conductive surface in an E-field is proportional to the strength of the field times the size of the surface. Use a smaller area, get a smaller signal. Scotty is right: "Ye canna change the laws of physics!." | ||
| N0TONE | 2002-08-22 | |
|---|---|---|
| RE: Small EH Antenna | ||
| The website mentioned early on was by an Italian ham who built an EH for 160 meters. He gave "results" with QSOs listed that seemed favorable. But, he obviously knew that did not provide particularly useful data - one need to compare with a "known" antenna. So he built a 160 meter vertical to compare it to. His 160 meter vertical was severely compromised, being all of 30 feet high, with only four too-short ground-mounted radials. A configuration which normally provides an antenna of maybe 5-10% efficiency. He then made lots of QSOs on both the EH and the poor vertical. In all cases, the vertical outperformed the EH by about 5-10dB. In his case, he either did not build the EH properly, or he demonstrated that EH performance is not superior. He remains open to either conclusion. There are some global points to be considered here: 1) Who cares if EH is operating with new theory? What we REALLY want to know is if this small antenna can do better than other small antenna designs. 2) Therefore, to satify #1, we need to see some genuine field strength tests made on EH antennas versus other small antennas, which are designed correctly. According to the Italian website referenced above, the 160 meter EH seems to be operating at about 0.5% efficiency. I have a 12 foot long mobile 160 meter antenna that does better than that! 3) NONE of the websites describing the EH antenna gives adequate information for measuring its performance. They make claims about the antenna's impedance, but do not tell you how to go about making those impedance measurements. I asked Ted Hart once how to make those impedance measurements and he said "measure the input impedance, then use math to calculate what the impedance is on the other side of the phasing network." But - he says the phasing network cannot be treated as a matching network, it requires new math. So, no go. I have built many small antennas over the years. By keeping the conductors big and fat where currents are high, and by using only low-loss dielectrics where the voltages are high, a small antenna can be made efficient. It won't be broadband, and it won't be 50 ohms. So the key with small antennas is not only proper construction, but then using good parts to effect the Z-match. Inductors in your matching network need to have large surface areas. #8 gauge or larger wire, or better yet, 1/4" copper tubing wound into inductors can be low loss. You have to trade off available space with desired Q. Capacitors are sometimes harder. There are no good low-loss dielectrics conveniently available. Coaxial cable makes a lossy capacitor. Window glass makes a poor dielectric. PVC and similar home construction materials have high losses when used as a capacitor dielectric. The best I've been able to do is make capacitors out of concentric copper pipes. I use PVC as a spacer, but try to minimize the number of those lossy spacers. I have a center-fed vertical for 80 meters, which is six feet high (that makes it fit my attic). My measurements show its efficiency to be about 25%. Most of the loss is in the matching network. That puts it 6dB down from a full-sized 80 meter vertical. Yes, I work DX on it, rather a lot of DX in fact. Bandwidth is only about 25kHz at the 2:1 points. If I drive it with 1.5kW, solid carrier, the antenna itself does not get warm at all, but the matching network does, mainly the inductor. So I know what part of my network could stand the most improvement. Use common sense. Don't worry about whether it's an EH or just a shortened center-fed vertical. Build the antenna, tune it as described, then do the "power" test. If you're on 160 or 80 meters, wait until daytime when the atmospheric absorption is so high that nobody can make a QSO. Lock your key for a few minutes, then shut down. Go feel the antenna to see what's warm, and work on reducing loss in that area. For 40 meters, about the only thing you can do like this is wait until nighttime when all the SW BC rolls in, and park your carrier zero-beat with a SW station, and do this same test. For 20, 15, and 10, there are lots of times when the band's dead. To the guy who said "In the meantime, the inventors of the E H antenna, Maurice C. Hately & Fathi M. Kabbary, or their employer (U.S. Patent No. 5,155,495), sure thought enough of this invention to spend some bucks on a patent attorney and filing fees. ", well, don't get too worked up. Filing patents is easy - there are books you can get that show you how to self-patent. Under $100 is the most you need to pay, unless you happen to like paying greedy corporate attorneys, or patent searchers. Yes, I'm such a person - willing to take big bucks to do things you can do yourself! Have fun guys, building antennas has more challenge and thrill than any other part of the technical side of the hobby. AM Reply to a comment by : N2KPE on 2002-08-21 WO5I: I would very much like to be kept posted on your results. Do you have any idea which band you will try/ I would especially be interested in 40. Tnx and 73. Reply to a comment by : WO5I on 2002-08-20 Folks, I am not a physicist or even an electrical engineer. But I am open-minded enough to NOT go disparaging the EH theory or design until I've tried it myself. I've seen several articles and web sites publishing results of experiments. Many of those results are favorable. For me to poo-poo it would be tantamount to me calling those hams, who I know nothing good or bad about, liars. Consider: Until Copernicus, the world thought the Earth was the center of the entire universe, and to openly state otherwise was a severe blaspheme, Until Columbus, the earth was thought to be flat (good for propagation, BAD for sailing!), Until Yager, the sound barrier was just that-- a barrier. Until Armstrong, et al, few really thought that there'd ever be a man on the moon (and probably some of the naysayers still think that all took place on a Hollywood soundstage). My challenge to the ham community that would write this idea off is this: build one yourself, per the directions on any of the published websites. They aren't expensive, they don't take any serious skill or expensive tools. The require a little patience to tune and fine-tune, but once it resonates, you can try it out head-to-head with any antenna you would otherwise use. I intend to put my money where my mouth is and build one. I might find I've wasted my time, then I will take my "I-told-you-so's" like a man. But then again, there are those that think of ham radio in general as one big waste of time! After all, isn't ham radio chock-full of people that experiment? Maybe the EH is a better mousetrap. | ||
| N2KPE | 2002-08-21 | |
|---|---|---|
| RE: Small EH Antenna | ||
| WO5I: I would very much like to be kept posted on your results. Do you have any idea which band you will try/ I would especially be interested in 40. Tnx and 73. Reply to a comment by : WO5I on 2002-08-20 Folks, I am not a physicist or even an electrical engineer. But I am open-minded enough to NOT go disparaging the EH theory or design until I've tried it myself. I've seen several articles and web sites publishing results of experiments. Many of those results are favorable. For me to poo-poo it would be tantamount to me calling those hams, who I know nothing good or bad about, liars. Consider: Until Copernicus, the world thought the Earth was the center of the entire universe, and to openly state otherwise was a severe blaspheme, Until Columbus, the earth was thought to be flat (good for propagation, BAD for sailing!), Until Yager, the sound barrier was just that-- a barrier. Until Armstrong, et al, few really thought that there'd ever be a man on the moon (and probably some of the naysayers still think that all took place on a Hollywood soundstage). My challenge to the ham community that would write this idea off is this: build one yourself, per the directions on any of the published websites. They aren't expensive, they don't take any serious skill or expensive tools. The require a little patience to tune and fine-tune, but once it resonates, you can try it out head-to-head with any antenna you would otherwise use. I intend to put my money where my mouth is and build one. I might find I've wasted my time, then I will take my "I-told-you-so's" like a man. But then again, there are those that think of ham radio in general as one big waste of time! After all, isn't ham radio chock-full of people that experiment? Maybe the EH is a better mousetrap. | ||
| K9FE | 2002-08-21 | |
|---|---|---|
| Small EH Antenna | ||
| OK, I built one for 20m. (well two)Took about 2 hours including rounding up the materials and getting it tuned to 14.200. It works! No it isn't going to put Force 12 out of business, but I have limitations on where and what I can put up. I was so floored that I brought it to a club meeting to show it off. Our club has a lot of techies but we never knock an idea until we can prove it wrong. A few members got excited and built them and they all worked. In our club we have EH antennas from 10m to 160m. AH6EZ Dick, is the big EH experimenter in our club and an engineer for Motorola who worked 47 states on 160 in one contest last year on an EH. His 160 is on the EH page of W0KPH. 10 feet tall and 16 inches in diameter and can handle over 600 watts! It works when it is 10 to 15 feet off the ground and suspended from a tree. Until you walk in a mans shoes do not call him a liar. Build this thing and build it right and it does work. Sure it defies any old antenna theory so if you do not believe it build it "correctly" and prove it does not work, I doubted it, but now I have 3, two for 20m and one for 40m. The 40m is only 24 inches tall but works better than my mobile 40m antenna...so I am going to mount it on the back of the car and use it...has better bandwidth than my center loaded mast. | ||
| N2HBX | 2002-08-21 | |
|---|---|---|
| Small EH Antenna | ||
| C'mon, guys. Let's not lose sight of the fact that this is a HOBBY, one that fortunately lends itself to all sorts of experimentation. What works for someone might not work for another, but if it doesn't, instead of just pooh-poohing it, try to se if you CAN make it work! I knew a gentleman by the name of Jim Waldron. His callsign escapes me at the moment, and I'm sure he is an SK by now. He founded a company called Com-Rad Industries. He had designed and manufactured shortened antennas similar to the EH design. In fact, he designed and sold similar antennas from 160 meters up to 450. Of course we had our local "experts" that said it didn't work and all his so-called "testimonials" that he had were all hired shills to talk up his units. But I sat in his shack for about two hours and tried them myself, and the results were satisfying. I never bought one (or built one) myself, but I thought they were kind of cool and seemed to work. His company was the progenitor of a company now known as Untenna (www.untenna.com). Apparently somebody thought the idea had merit, even though the current company specializes in commercial two-way antennas and has left the ham market. Point is, don't get caught up in the physics of it all. If the laws of physics applied to everything literally, bumblebees couldn't fly. | ||
| W7KWS | 2002-08-21 | |
|---|---|---|
| RE: Small EH Antenna | ||
| William (W3JJH), The problem that I see with your ideas about size of an antenna relating to its efficiency is that, while size is a factor, it is not the only factor involved. Your comparison of an isotropic source to a dipole suggests that a dipole radiates more energy than the point source. The fact is that it does not. Except for heat conversion in the resistance of both antennas and assuming for the moment that there are equal or no feed line losses, both antennas radiate exactly the same amount of energy, regardless of size. The differences you describe are due to the directional nature of the dipole versus the fact that the isotropic antenna distributes its energy equally in all directions, therefore, no one direction benefits over another, as is the case with the dipole. Regarding wire length versus antenna efficiency, I quote from my copy of the 5th edition of the Reference Data for Radio Engineers, page 25-7; “In addition, antenna efficiencies vary from about 70 percent for a 0.15-wavelength physical height to over 95 percent for a 0.6 wavelength height. This is for a vertical, and doesn’t account for why a loop can be above 90 percent, but it does show that a very short antenna of 0.15 wavelength can still radiate with more efficiency than one would suspect from a linear formula such as you proposed in your previous post. Make no mistake, I doubt that the EH Antenna works very well, but I know that the tuned loop does. And, it is a small antenna. In facts, it can be a small fraction of a wavelength and approach the efficiency of a dipole. This is because factors other than size are involved. If you can get a copy of any ARRL Antenna book and read about it, you will see that it is true. Also, you no longer need an extensive antenna range to determine the value of an antenna. There are many very good computer modeling programs that produce results that are very close to what you would find on an antenna range. Believe it or not, we only think we have a handle on physics. People are proving every day that even Einstein didn’t have it all right. THERE ARE NEW THINGS TO DISCOVER ALL THE TIME. Even the fact that a small antenna like the tuned loop can work very well compared with much larger antennas. Whether the EH Antenna is a good one is a simple matter of analysis. I wish I had those analytical skills myself, but I don’t, so I rely on the published references of those that do have the skills. The loop has been studied for years and has been proven to work. Maybe we can attract someone to this discussion that can do a computer model of the EH antenna and give us some real data that we can rely on. 73, Bob Reply to a comment by : W3JJH on 2002-08-21 I don't have a copy of the reference which W3KWS cites, but please allow me to make some further comments. The "mechanics" of wave propagation are well known and have been rigorously descirbed for about 150 years now. Most electrical engineering students take a course in Fields & Waves during their junior or senior year. In that course they learn that small radiators approximate a point source; such antennas have omnidirectional patterns and radiate equally poorly in all directions. Large radiators are more efficient, but are also more directive. For example, a half-wave dipole works well to the sides, but is deaf and dumb off the ends. Extremely large radiators generally do not work well because of phasing problems with the signals coming from different points on the antenna. Note that a small antenna that has an efficiency many dB lower than a dipole may hear a signal coming from a bearing off the end of the dipole better than the larger antenna. As an analogy, consider a set of loudspeakers. It is possible to construct two different loudspeakers systems which have the same low frequency cutoff using different size drivers and enclosures. Let's say we want a 20-Hz low end cutoff, and we build one system with a 38-cm (15-in) driver in a 600-l (21 cu ft) enclosure. The system efficiency will be roughly 1 %. If we build the other system with a 11-cm (4-1/2-in) driver in a 30-l (1.1 cu ft) box, the system efficiency will be around 0.05 %. At low frequencies we'll be able to get the same sound level out of the second system only if we use 20X the amplifier power. However, the smaller system will do a better job of reproducing signals above 1-kHz; the bigger woofer becomes an extremely large radiator at these frequencies. This is why a proper audio system has a woofer and a tweeter (at least!). Similarly, we shouldn't use a 2-m ground plane on 80-m or an 80-m vertical on 2-m. HF antenna testing requires large, open spaces and calibrated test gear which most of us do not possess. Even some manufacturers of HF antennas do not have a proper antenna test range. I take all antenna performance claims with a grain of salt until I have verified that test data actually exists and was properly measured. I live on a small city lot. I can just fit a 70-ft dipole with loading inductors on my site. Fed with ladder line, it works sorta OK on all the bands from 160 through 10. I also have an Outbacker on an Alpha-Delta stand. In some cases (depending on the bearing to the other station or signal vertical arrival angle) it works better than the dipole. But, except on the 12- and 10-m bands, it is a less efficent radiator than the dipole. Reply to a comment by : W7KWS on 2002-08-20 In using wire length as a linear indicator of signal capture/radiation efficiency (presumed law of physics in previous post), how do you account for the fact that a tuned magnetic loop antenna, at 8.5 Ft. in circumference, is only down 1.0 dB below a "large antenna" for the same band? Reference the ARRL Antenna Handbook, 16th edition, page 5-13, loop design No. 5. Good wishes to all in hopes we all learn here. 73, Bob, W7KWS Reply to a comment by : W3JJH on 2002-08-20 I'm open-minded, but not so open-minded that my brain has fallen out. 1. My dummy load has a 1.1:1 SWR on 20-m. It doesn't radiate very well. 2. At 6 dB/S-unit, a drop of 1-1/2 S-units represents a 90-% power loss. If the signals coming in the side of my dipole were only 9 dB above those from a small "EH" antenna, I would start checking for loose or corroded connections on the dipole. The current in a wire in an H-field is proportional to the strength of field times the length of the wire. Use a shorter wire, get a smaller signal. The potential on a conductive surface in an E-field is proportional to the strength of the field times the size of the surface. Use a smaller area, get a smaller signal. Scotty is right: "Ye canna change the laws of physics!." | ||
| W3JJH | 2002-08-21 | |
|---|---|---|
| RE: Small EH Antenna | ||
| I don't have a copy of the reference which W3KWS cites, but please allow me to make some further comments. The "mechanics" of wave propagation are well known and have been rigorously descirbed for about 150 years now. Most electrical engineering students take a course in Fields & Waves during their junior or senior year. In that course they learn that small radiators approximate a point source; such antennas have omnidirectional patterns and radiate equally poorly in all directions. Large radiators are more efficient, but are also more directive. For example, a half-wave dipole works well to the sides, but is deaf and dumb off the ends. Extremely large radiators generally do not work well because of phasing problems with the signals coming from different points on the antenna. Note that a small antenna that has an efficiency many dB lower than a dipole may hear a signal coming from a bearing off the end of the dipole better than the larger antenna. As an analogy, consider a set of loudspeakers. It is possible to construct two different loudspeakers systems which have the same low frequency cutoff using different size drivers and enclosures. Let's say we want a 20-Hz low end cutoff, and we build one system with a 38-cm (15-in) driver in a 600-l (21 cu ft) enclosure. The system efficiency will be roughly 1 %. If we build the other system with a 11-cm (4-1/2-in) driver in a 30-l (1.1 cu ft) box, the system efficiency will be around 0.05 %. At low frequencies we'll be able to get the same sound level out of the second system only if we use 20X the amplifier power. However, the smaller system will do a better job of reproducing signals above 1-kHz; the bigger woofer becomes an extremely large radiator at these frequencies. This is why a proper audio system has a woofer and a tweeter (at least!). Similarly, we shouldn't use a 2-m ground plane on 80-m or an 80-m vertical on 2-m. HF antenna testing requires large, open spaces and calibrated test gear which most of us do not possess. Even some manufacturers of HF antennas do not have a proper antenna test range. I take all antenna performance claims with a grain of salt until I have verified that test data actually exists and was properly measured. I live on a small city lot. I can just fit a 70-ft dipole with loading inductors on my site. Fed with ladder line, it works sorta OK on all the bands from 160 through 10. I also have an Outbacker on an Alpha-Delta stand. In some cases (depending on the bearing to the other station or signal vertical arrival angle) it works better than the dipole. But, except on the 12- and 10-m bands, it is a less efficent radiator than the dipole. Reply to a comment by : W7KWS on 2002-08-20 In using wire length as a linear indicator of signal capture/radiation efficiency (presumed law of physics in previous post), how do you account for the fact that a tuned magnetic loop antenna, at 8.5 Ft. in circumference, is only down 1.0 dB below a "large antenna" for the same band? Reference the ARRL Antenna Handbook, 16th edition, page 5-13, loop design No. 5. Good wishes to all in hopes we all learn here. 73, Bob, W7KWS Reply to a comment by : W3JJH on 2002-08-20 I'm open-minded, but not so open-minded that my brain has fallen out. 1. My dummy load has a 1.1:1 SWR on 20-m. It doesn't radiate very well. 2. At 6 dB/S-unit, a drop of 1-1/2 S-units represents a 90-% power loss. If the signals coming in the side of my dipole were only 9 dB above those from a small "EH" antenna, I would start checking for loose or corroded connections on the dipole. The current in a wire in an H-field is proportional to the strength of field times the length of the wire. Use a shorter wire, get a smaller signal. The potential on a conductive surface in an E-field is proportional to the strength of the field times the size of the surface. Use a smaller area, get a smaller signal. Scotty is right: "Ye canna change the laws of physics!." | ||
| K3AN | 2002-08-21 | |
|---|---|---|
| RE: Small EH Antenna | ||
| I am on the verge of achieving a radical breakthrough that will finally achieve the dream of almost limitless free power from plain old water! Since water consists of just hydrogen and oxygen, combining those elements to release the power results in no pollution. I will be prepared to demonstrate this publicly in the near future. To the invitees of that demonstration, I must ask in advance that they pay no attention to the man behind the curtain ;-) Reply to a comment by : W7KWS on 2002-08-20 I forgot, the band of reference in my last post is for 20 meters (14.2 MHz.). Reply to a comment by : W7KWS on 2002-08-20 In using wire length as a linear indicator of signal capture/radiation efficiency (presumed law of physics in previous post), how do you account for the fact that a tuned magnetic loop antenna, at 8.5 Ft. in circumference, is only down 1.0 dB below a "large antenna" for the same band? Reference the ARRL Antenna Handbook, 16th edition, page 5-13, loop design No. 5. Good wishes to all in hopes we all learn here. 73, Bob, W7KWS Reply to a comment by : W3JJH on 2002-08-20 I'm open-minded, but not so open-minded that my brain has fallen out. 1. My dummy load has a 1.1:1 SWR on 20-m. It doesn't radiate very well. 2. At 6 dB/S-unit, a drop of 1-1/2 S-units represents a 90-% power loss. If the signals coming in the side of my dipole were only 9 dB above those from a small "EH" antenna, I would start checking for loose or corroded connections on the dipole. The current in a wire in an H-field is proportional to the strength of field times the length of the wire. Use a shorter wire, get a smaller signal. The potential on a conductive surface in an E-field is proportional to the strength of the field times the size of the surface. Use a smaller area, get a smaller signal. Scotty is right: "Ye canna change the laws of physics!." | ||
| W7KWS | 2002-08-20 | |
|---|---|---|
| RE: Small EH Antenna | ||
| I forgot, the band of reference in my last post is for 20 meters (14.2 MHz.). Reply to a comment by : W7KWS on 2002-08-20 In using wire length as a linear indicator of signal capture/radiation efficiency (presumed law of physics in previous post), how do you account for the fact that a tuned magnetic loop antenna, at 8.5 Ft. in circumference, is only down 1.0 dB below a "large antenna" for the same band? Reference the ARRL Antenna Handbook, 16th edition, page 5-13, loop design No. 5. Good wishes to all in hopes we all learn here. 73, Bob, W7KWS Reply to a comment by : W3JJH on 2002-08-20 I'm open-minded, but not so open-minded that my brain has fallen out. 1. My dummy load has a 1.1:1 SWR on 20-m. It doesn't radiate very well. 2. At 6 dB/S-unit, a drop of 1-1/2 S-units represents a 90-% power loss. If the signals coming in the side of my dipole were only 9 dB above those from a small "EH" antenna, I would start checking for loose or corroded connections on the dipole. The current in a wire in an H-field is proportional to the strength of field times the length of the wire. Use a shorter wire, get a smaller signal. The potential on a conductive surface in an E-field is proportional to the strength of the field times the size of the surface. Use a smaller area, get a smaller signal. Scotty is right: "Ye canna change the laws of physics!." | ||
| W7KWS | 2002-08-20 | |
|---|---|---|
| RE: Small EH Antenna | ||
| In using wire length as a linear indicator of signal capture/radiation efficiency (presumed law of physics in previous post), how do you account for the fact that a tuned magnetic loop antenna, at 8.5 Ft. in circumference, is only down 1.0 dB below a "large antenna" for the same band? Reference the ARRL Antenna Handbook, 16th edition, page 5-13, loop design No. 5. Good wishes to all in hopes we all learn here. 73, Bob, W7KWS Reply to a comment by : W3JJH on 2002-08-20 I'm open-minded, but not so open-minded that my brain has fallen out. 1. My dummy load has a 1.1:1 SWR on 20-m. It doesn't radiate very well. 2. At 6 dB/S-unit, a drop of 1-1/2 S-units represents a 90-% power loss. If the signals coming in the side of my dipole were only 9 dB above those from a small "EH" antenna, I would start checking for loose or corroded connections on the dipole. The current in a wire in an H-field is proportional to the strength of field times the length of the wire. Use a shorter wire, get a smaller signal. The potential on a conductive surface in an E-field is proportional to the strength of the field times the size of the surface. Use a smaller area, get a smaller signal. Scotty is right: "Ye canna change the laws of physics!." | ||
| K1OU | 2002-08-20 | |
|---|---|---|
| RE: Small EH Antenna | ||
| What? No opinion yet from WB2WIK/6? Reply to a comment by : KA1OGM on 2002-08-20 This subject is always one that elicits contentious debate regarding claims made by commercial interests. It also brings out a fair number of those who are not only knowledgable and technically savvy who have investigated one or more of these designs, but also those who have blindly stumbled onto them and been quite excited about what they ended up with. Anyone who is serious about efficient antennas will have issues with the two cylinder plus coil design, however, because it really isn't a very good antenna. But compared to NO antenna this is one of the more intriguing designs around because it's small enough to be used indoors. I, for one, cannot operate a 75m loop in my basement and make contact with anyone, near or far. I can, however, operate a two cylinder plus coil antenna for 75m in my basement and maintain contact with everyone I've tried this with, when first making contact with my outdoor inverted Vee (and vice-versa). I even got a qsl e-mail from an SWL 500 miles away who heard me making a test one night on 75m AM. Admittedly, my effective radiated power is a tenth of what it was on the outside antenna, but I have to say that if I was restricted to an apartment, this would be my antenna. Like I pointed out in my last post, nobody's making any wild claims about this design, and nobody will ever dispute that a monoband directive array is better. What's nice about this design is you can make it sloppily and still get on the air, where otherwise you might not be able to get on the air at all. Jeff Barnard KA1OGM | ||
| W3JJH | 2002-08-20 | |
|---|---|---|
| Small EH Antenna | ||
| I'm open-minded, but not so open-minded that my brain has fallen out. 1. My dummy load has a 1.1:1 SWR on 20-m. It doesn't radiate very well. 2. At 6 dB/S-unit, a drop of 1-1/2 S-units represents a 90-% power loss. If the signals coming in the side of my dipole were only 9 dB above those from a small "EH" antenna, I would start checking for loose or corroded connections on the dipole. The current in a wire in an H-field is proportional to the strength of field times the length of the wire. Use a shorter wire, get a smaller signal. The potential on a conductive surface in an E-field is proportional to the strength of the field times the size of the surface. Use a smaller area, get a smaller signal. Scotty is right: "Ye canna change the laws of physics!." | ||
| KA1OGM | 2002-08-20 | |
|---|---|---|
| Small EH Antenna | ||
| This subject is always one that elicits contentious debate regarding claims made by commercial interests. It also brings out a fair number of those who are not only knowledgable and technically savvy who have investigated one or more of these designs, but also those who have blindly stumbled onto them and been quite excited about what they ended up with. Anyone who is serious about efficient antennas will have issues with the two cylinder plus coil design, however, because it really isn't a very good antenna. But compared to NO antenna this is one of the more intriguing designs around because it's small enough to be used indoors. I, for one, cannot operate a 75m loop in my basement and make contact with anyone, near or far. I can, however, operate a two cylinder plus coil antenna for 75m in my basement and maintain contact with everyone I've tried this with, when first making contact with my outdoor inverted Vee (and vice-versa). I even got a qsl e-mail from an SWL 500 miles away who heard me making a test one night on 75m AM. Admittedly, my effective radiated power is a tenth of what it was on the outside antenna, but I have to say that if I was restricted to an apartment, this would be my antenna. Like I pointed out in my last post, nobody's making any wild claims about this design, and nobody will ever dispute that a monoband directive array is better. What's nice about this design is you can make it sloppily and still get on the air, where otherwise you might not be able to get on the air at all. Jeff Barnard KA1OGM | ||
| KE4MOB | 2002-08-20 | |
|---|---|---|
| RE: Small EH Antenna | ||
| How do you generate an E field without generating an H field? Could somebody explain this to me? Steve, KE4MOB Reply to a comment by : KD3V on 2002-08-20 !!! LISTEN UP SKEPTICS !!! Please stop making fools of yourselves! If you haven't tried it you have NO BASIS for saying anything! We made one! I used it! it works! I am an electrical engineer. I have been one since 1982. These EH antennas in fact: 1. ... are not "getting something for nothing", 2. they are not "changing the laws of physics in order to make something better than it is", 3. they agree completely with the law of physics that tells us how to get radiation, and for those that have taken the time to read the relevant website, this is called the "Poynting Theorem". This antenna is simple a DIFFERENT method to work this "law of physics". 4. They WORK! I know because I used one! I sent the article to a friend who wanted to make one, he had a friend of his duplicate the 20 meter version that was detailed on the web site. He used it and then I put it up in place on the roof. Simply put, I worked the world on it! I live in Hollywood Calif. From John in South Africa, a 5-7 ... on the LONG path... a FM5 in Martinique, VK's ZL's ZK1, you name it and I only had it for 3 days! So! Read the web sites! These antennas are not using feedline rariation, they are genuine rariators using a different method to create the crossed EM field and as a result they do not need the "linear" distance used by a diplole! These antennas just do it DIFFERENTLY! Yea, i get upset by the "ignorant" who speak up with no basis from which to do so. In the place of facts you put baseless opinion, and in the place of knowledge you put "authority". You are all only making fools of yourselves and those of us who take the time to "find out for ourselves" are the ones who gain real knowledge! We were curious so we built one and we found that it works! Simple. We didn't know until we tried... but we also didn't try to slam it until we KNEW something about which we wanted to speak! I would have posted a few photos but you can already see them when you go read the web site referenced! Ours looked just like theirs do. We used copper plate wrapped around PVC cylinder. Total length.. just like on the website! http://www.qsl.net/w0kph/ This is the link that describes the "full network" verion that our friend built. http://www.qsl.net/w0kph/fullnet.html | ||
| KE4MOB | 2002-08-20 | |
|---|---|---|
| RE: Small EH Antenna | ||
| How do you generate an E field without generating an H field? Could somebody explain this to me? Steve, KE4MOB Reply to a comment by : KD3V on 2002-08-20 !!! LISTEN UP SKEPTICS !!! Please stop making fools of yourselves! If you haven't tried it you have NO BASIS for saying anything! We made one! I used it! it works! I am an electrical engineer. I have been one since 1982. These EH antennas in fact: 1. ... are not "getting something for nothing", 2. they are not "changing the laws of physics in order to make something better than it is", 3. they agree completely with the law of physics that tells us how to get radiation, and for those that have taken the time to read the relevant website, this is called the "Poynting Theorem". This antenna is simple a DIFFERENT method to work this "law of physics". 4. They WORK! I know because I used one! I sent the article to a friend who wanted to make one, he had a friend of his duplicate the 20 meter version that was detailed on the web site. He used it and then I put it up in place on the roof. Simply put, I worked the world on it! I live in Hollywood Calif. From John in South Africa, a 5-7 ... on the LONG path... a FM5 in Martinique, VK's ZL's ZK1, you name it and I only had it for 3 days! So! Read the web sites! These antennas are not using feedline rariation, they are genuine rariators using a different method to create the crossed EM field and as a result they do not need the "linear" distance used by a diplole! These antennas just do it DIFFERENTLY! Yea, i get upset by the "ignorant" who speak up with no basis from which to do so. In the place of facts you put baseless opinion, and in the place of knowledge you put "authority". You are all only making fools of yourselves and those of us who take the time to "find out for ourselves" are the ones who gain real knowledge! We were curious so we built one and we found that it works! Simple. We didn't know until we tried... but we also didn't try to slam it until we KNEW something about which we wanted to speak! I would have posted a few photos but you can already see them when you go read the web site referenced! Ours looked just like theirs do. We used copper plate wrapped around PVC cylinder. Total length.. just like on the website! http://www.qsl.net/w0kph/ This is the link that describes the "full network" verion that our friend built. http://www.qsl.net/w0kph/fullnet.html | ||
| KD3V | 2002-08-20 | |
|---|---|---|
| Small EH Antenna | ||
| !!! LISTEN UP SKEPTICS !!! Please stop making fools of yourselves! If you haven't tried it you have NO BASIS for saying anything! We made one! I used it! it works! I am an electrical engineer. I have been one since 1982. These EH antennas in fact: 1. ... are not "getting something for nothing", 2. they are not "changing the laws of physics in order to make something better than it is", 3. they agree completely with the law of physics that tells us how to get radiation, and for those that have taken the time to read the relevant website, this is called the "Poynting Theorem". This antenna is simple a DIFFERENT method to work this "law of physics". 4. They WORK! I know because I used one! I sent the article to a friend who wanted to make one, he had a friend of his duplicate the 20 meter version that was detailed on the web site. He used it and then I put it up in place on the roof. Simply put, I worked the world on it! I live in Hollywood Calif. From John in South Africa, a 5-7 ... on the LONG path... a FM5 in Martinique, VK's ZL's ZK1, you name it and I only had it for 3 days! So! Read the web sites! These antennas are not using feedline rariation, they are genuine rariators using a different method to create the crossed EM field and as a result they do not need the "linear" distance used by a diplole! These antennas just do it DIFFERENTLY! Yea, i get upset by the "ignorant" who speak up with no basis from which to do so. In the place of facts you put baseless opinion, and in the place of knowledge you put "authority". You are all only making fools of yourselves and those of us who take the time to "find out for ourselves" are the ones who gain real knowledge! We were curious so we built one and we found that it works! Simple. We didn't know until we tried... but we also didn't try to slam it until we KNEW something about which we wanted to speak! I would have posted a few photos but you can already see them when you go read the web site referenced! Ours looked just like theirs do. We used copper plate wrapped around PVC cylinder. Total length.. just like on the website! http://www.qsl.net/w0kph/ This is the link that describes the "full network" verion that our friend built. http://www.qsl.net/w0kph/fullnet.html | ||
| KE4MOB | 2002-08-20 | |
|---|---|---|
| RE: Small EH Antenna | ||
| I think it's important to realize you can work QRP using only an ordinary lightbulb as an antenna. And people regularly load up metal guttering with fair results. Sometimes they can work stations using dummy loads for antennas. We would like to think antennas are wonderfully complex instruments...fact is, you can radiate a workable signal with darn near anything. This antenna is probably a perfect example. They used to have a lot of info at www.antennex.com...I thought the so-called "tests" in Egypt were a failure? Steve, KE4MOB Reply to a comment by : WA4DOU on 2002-08-20 Flat earth? Closed minds? Unreceptive to new ideas? Since when did inefficient antennas become a new idea, warrenting much experimentation? In free space, a theoretical point source of electromagnetic radiation is called an isotropic antenna. It is the point of reference we use to understand the 1/4 wavelength and 1/2 wavelength antennas, also in free space. The quarterwave displays a "gain" of about 1 db over this isotropic reference and the halfwave displays a "gain" of about 2.14 db. These can be turned around to state that an isotropic antenna has negative gain of 2.14 db over a half-wave antenna and negative 1 db over a quarterwave. Bring both of these antennas into close proximity to the earth and you have gain over them in free space, because of ground reflections. These are the real world reference standards by which we understand more complex antennas. 1 to 1-1/2 S unit down equates to about 50-90 % power loss. Why would you generate expensive r.f. energy and then be content to throw away 50-90% of it? Wouldn't it be better to generate less of it and radiate it more efficiently? I have lived in many places as an adult and I have experimented with many antennas. A common thread thru it all is that when you seriously shorten an antenna, you seriously diminish its performance. I have lived in beehives, townhouses, duplexes, mobile homes, single family dwellings, with and without antenna restrictions. I have used my share of clandestine antennas and I have never seen a circumstance where I couldn't erect outside antennas. All it takes is imagination and willpower. Any are to be preferred over any of these newfangled miracle antennas that promise much and deliver much less. Do what you please. I'll continue to use real antennas that deliver real performance. Reply to a comment by : KG6AMW on 2002-08-20 Dick, I've seen some off color comments, but they don't seem ill tempered. Its the way a discussion goes. Some believe it, some don't, and some want more evidence. Until you obtain data in a controlled environment and put it into a report, all we have are just comments. Merrill | ||
| WO5I | 2002-08-20 | |
|---|---|---|
| RE: Small EH Antenna | ||
| It's OK, Roy. Nobody, least of all ME, is asking you to take your proven antenna to the dump in favor of something untried or inferior. My point, and that of several others on this thread so far, is to say "why not?" to the idea of EH. I'm not encumbered by a vast knowledge of antenna theory which prevents me from hoping that something like this would work. I read the article in World Radio, and all the negative comments regarding the antenna, and am unarmed to argue any of the theoritical points. The EH could very well end up being the "cold fusion" of antennas. However, I've also read some good comments and favorable test results and think that the EH antenna is worth a weekend's worth of my time to tinker with. Even if the thing won't radiate beyond my back yard, I'll get to sharpen some rusty skills at forming aluminum foil, winding coils of wire, cutting PVC pipe or cardboard tube -- skills that will undoubtedly bail me out of some unforeseen jam like McGyver with a magnifying glass. This argument, or friendly ham-like discussion, is akin to arguing the merits of of QRO vs. QRP. Nobody will dispute that the 1.5KW and stacked monobanders will be heard much clearer through a pile up than an FT-817 and telescoping whip, but try stuffing your Alpha amp and tower into your backpack! I, too, have found somewhat clever ways to radiate in adverse housing conditions. My current solution is to thumb my nose at the CC&R and ground-mount a very low-footprint multi-band vertical, hoping any neighbors that might care about such things will assume it's a deep sea fishing pole (actually had one neighbor THINK THAT! HI HI). The EH is just another option in the realm of possibility. Let beauty be in the eye of the beholder. Reply to a comment by : WA4DOU on 2002-08-20 Flat earth? Closed minds? Unreceptive to new ideas? Since when did inefficient antennas become a new idea, warrenting much experimentation? In free space, a theoretical point source of electromagnetic radiation is called an isotropic antenna. It is the point of reference we use to understand the 1/4 wavelength and 1/2 wavelength antennas, also in free space. The quarterwave displays a "gain" of about 1 db over this isotropic reference and the halfwave displays a "gain" of about 2.14 db. These can be turned around to state that an isotropic antenna has negative gain of 2.14 db over a half-wave antenna and negative 1 db over a quarterwave. Bring both of these antennas into close proximity to the earth and you have gain over them in free space, because of ground reflections. These are the real world reference standards by which we understand more complex antennas. 1 to 1-1/2 S unit down equates to about 50-90 % power loss. Why would you generate expensive r.f. energy and then be content to throw away 50-90% of it? Wouldn't it be better to generate less of it and radiate it more efficiently? I have lived in many places as an adult and I have experimented with many antennas. A common thread thru it all is that when you seriously shorten an antenna, you seriously diminish its performance. I have lived in beehives, townhouses, duplexes, mobile homes, single family dwellings, with and without antenna restrictions. I have used my share of clandestine antennas and I have never seen a circumstance where I couldn't erect outside antennas. All it takes is imagination and willpower. Any are to be preferred over any of these newfangled miracle antennas that promise much and deliver much less. Do what you please. I'll continue to use real antennas that deliver real performance. Reply to a comment by : KG6AMW on 2002-08-20 Dick, I've seen some off color comments, but they don't seem ill tempered. Its the way a discussion goes. Some believe it, some don't, and some want more evidence. Until you obtain data in a controlled environment and put it into a report, all we have are just comments. Merrill | ||
| N3HKN | 2002-08-20 | |
|---|---|---|
| RE: Small EH Antenna | ||
| First, the insulting and ill-tempered remarks above are disgusting. Why are such people so angry that they must sit around and await any opportunity to lash out with blind criticisim. I hope that these poor representitives of the Ham community are in a very small minority. I have not built one of these antennas but I do have restrictions and have read the info on the associated web sites. Now that someone has "independently" constructed one I will try it. What harm can it do? Perhaps that is the question the above "personalities" should ponder as they sit in their dark little rooms doing whatever people like that do in private. I will take a shot at the 20 meter version and see how it compares to my Gap Challenger vertical dipole. This is a fair comparison due to efficiency and angle of radiation. By the way, GAP has a similar multiband unit for over $400 for sale. I have yet to hear about any real-world results on this unit. It uses a flat plate with a metal box about a foot above it supported on an insulator. From articles in Antenna-X the tuning unit is the critical element. Dick N3HKN Reply to a comment by : KA1OGM on 2002-08-20 In case no-one noticed, the initial post on this topic contains clear and explicit performance claims of 1 to 1-1/2 S-units down, in comparison to his full sized antenna. This is the same general performance that I've experienced with the design shown in the picture, over the past year and a half. The controversy of the past ten years surrounding the CFA and EH antennas are founded upon claims that they perform as well as, or better than full sized antennas. We are dealing with a design here that can be used for restricted space situations with the expected reduced performance. Nobody has come onto this thread making any wild claims that defy the laws of physics, or the basic math for antenna design that was worked out a century ago. That Kabbary of "CFA" and Ted Hart of "EH" have been working on commercial applications all this time really has very little to do with the application of this compact, reduced performance alternative for ham radio applications. This is a ground level vertical design that can be experimented with to achieve low angles of radiation. The longer the cylinders are, the lower the angle of radiation (to a point). Even lower angles of radiation can be achieved by using plates that are shaped like inverted cones, or a cone-disk arrangement, all of which is described in detail for practical construction on Jack Arnold's website at: http://www.qsl.net/w0kph/ The "catch" with these antennas is that with lower angles of radiation, some claims might ring true about performance exceeding that of a single element full sized antenna, but most hams will find performance running down by 1 to 2 S-units in comparison to any full sized antennas they have at the same location. In many experiments I've done, however, I've gotten "hot" angles on the short, fat dipoles that produce better Rx and Tx performance working DX stations out at that favorable distance for the angle. This is a VERY interesting antenna design in this respect, and it bears scrutiny and investigation by those who would actually experiment with them. And yes, there ARE some perplexing phenomena that can be produced when using these antennas. They are intriguing, and lead me to suspect that there are things going on with these designs that have yet to be adequately explained. Of course, if you never experiment with these things to any significant degree, you'll never get to that head scratching point, and you'll never have a chance to find out what I'm referring to. Jeff Barnard KA1OGM | ||
| KG6AMW | 2002-08-20 | |
|---|---|---|
| Small EH Antenna | ||
| Weak signal, low EMI. Strong signal, high EMI. | ||
| KA1OGM | 2002-08-20 | |
|---|---|---|
| Small EH Antenna | ||
| In case no-one noticed, the initial post on this topic contains clear and explicit performance claims of 1 to 1-1/2 S-units down, in comparison to his full sized antenna. This is the same general performance that I've experienced with the design shown in the picture, over the past year and a half. The controversy of the past ten years surrounding the CFA and EH antennas are founded upon claims that they perform as well as, or better than full sized antennas. We are dealing with a design here that can be used for restricted space situations with the expected reduced performance. Nobody has come onto this thread making any wild claims that defy the laws of physics, or the basic math for antenna design that was worked out a century ago. That Kabbary of "CFA" and Ted Hart of "EH" have been working on commercial applications all this time really has very little to do with the application of this compact, reduced performance alternative for ham radio applications. This is a ground level vertical design that can be experimented with to achieve low angles of radiation. The longer the cylinders are, the lower the angle of radiation (to a point). Even lower angles of radiation can be achieved by using plates that are shaped like inverted cones, or a cone-disk arrangement, all of which is described in detail for practical construction on Jack Arnold's website at: http://www.qsl.net/w0kph/ The "catch" with these antennas is that with lower angles of radiation, some claims might ring true about performance exceeding that of a single element full sized antenna, but most hams will find performance running down by 1 to 2 S-units in comparison to any full sized antennas they have at the same location. In many experiments I've done, however, I've gotten "hot" angles on the short, fat dipoles that produce better Rx and Tx performance working DX stations out at that favorable distance for the angle. This is a VERY interesting antenna design in this respect, and it bears scrutiny and investigation by those who would actually experiment with them. And yes, there ARE some perplexing phenomena that can be produced when using these antennas. They are intriguing, and lead me to suspect that there are things going on with these designs that have yet to be adequately explained. Of course, if you never experiment with these things to any significant degree, you'll never get to that head scratching point, and you'll never have a chance to find out what I'm referring to. Jeff Barnard KA1OGM | ||
| WA4DOU | 2002-08-20 | |
|---|---|---|
| RE: Small EH Antenna | ||
| Flat earth? Closed minds? Unreceptive to new ideas? Since when did inefficient antennas become a new idea, warrenting much experimentation? In free space, a theoretical point source of electromagnetic radiation is called an isotropic antenna. It is the point of reference we use to understand the 1/4 wavelength and 1/2 wavelength antennas, also in free space. The quarterwave displays a "gain" of about 1 db over this isotropic reference and the halfwave displays a "gain" of about 2.14 db. These can be turned around to state that an isotropic antenna has negative gain of 2.14 db over a half-wave antenna and negative 1 db over a quarterwave. Bring both of these antennas into close proximity to the earth and you have gain over them in free space, because of ground reflections. These are the real world reference standards by which we understand more complex antennas. 1 to 1-1/2 S unit down equates to about 50-90 % power loss. Why would you generate expensive r.f. energy and then be content to throw away 50-90% of it? Wouldn't it be better to generate less of it and radiate it more efficiently? I have lived in many places as an adult and I have experimented with many antennas. A common thread thru it all is that when you seriously shorten an antenna, you seriously diminish its performance. I have lived in beehives, townhouses, duplexes, mobile homes, single family dwellings, with and without antenna restrictions. I have used my share of clandestine antennas and I have never seen a circumstance where I couldn't erect outside antennas. All it takes is imagination and willpower. Any are to be preferred over any of these newfangled miracle antennas that promise much and deliver much less. Do what you please. I'll continue to use real antennas that deliver real performance. Reply to a comment by : KG6AMW on 2002-08-20 Dick, I've seen some off color comments, but they don't seem ill tempered. Its the way a discussion goes. Some believe it, some don't, and some want more evidence. Until you obtain data in a controlled environment and put it into a report, all we have are just comments. Merrill | ||
| W2BRI | 2002-08-20 | |
|---|---|---|
| RE: Small EH Antenna | ||
| Being very interested in all types of antennas I went out and built an EH antenna. Darn thing was so small and cute. I put it outside and compared it to my triband yagi...probably not a fair comparison. The EH while attractive and fun, did not seem to hear very well. Yeah, I got a good match, and my family made all sorts of funny remarks about my magic wand, but it worked horribly. I don't mean bad, I mean horribly. Maybe I did something wrong --as some might like to point out. And maybe I did. But it took me about 5 minutes to realize, my EH didn't work a darn. Now if someone is interested in small antennas that really work, I would strongly suggest building a magnetic loop antenna. My 80 meter 12x12 2 inch thick mag loop works great! and for the size you can't beat it on 80. Sure, you could build a smaller one if you want. I highly recommend this antenna and you don't have to re-write physics in the process. Please email me if you would like more info. Reply to a comment by : KG6AMW on 2002-08-20 Dick, I've seen some off color comments, but they don't seem ill tempered. Its the way a discussion goes. Some believe it, some don't, and some want more evidence. Until you obtain data in a controlled environment and put it into a report, all we have are just comments. Merrill | ||
| KE0VH | 2002-08-20 | |
|---|---|---|
| RE: Small EH Antenna | ||
| I did post this same article at QRZ.com a couple of months ago, and first of all it took Eham forever to put it up. The reason I wrote it was to help out fellow hams who might not know about a smaller design that will help in maybe a situation where someone can't put up a full size beam, or dipole, and and have a kilowatt like a lot of people who gripe when someone comes up with a new idea. Frankly, I am really irritated that so many come on and "diss" an idea without even having tried it. I am an RF/radio engineer with years of experience building antenna's and wouldn't put up something that was bogus. I am NOT trying to SELL anything, just SHARE AN IDEA. Those of you who are critical probably haven't even tried it. The Antenna DOES work. If a corporation or company has the money to design and produce a smaller antenna that does, like MFJ and the like, GREAT! If not, how about just sharing ideas that work without having to have a high and mighty opinion without having tried it. Check your attitude people. Lets respect others viewpoints and WORK folks, and unless you have tried it frankly I think you should keep your critical views to yourself. Try it and put some work into and then present your results. I did. Otherwise, let those of us who are willing to experiment a little bit, build and try things and try to help others do so without the "benefit" of your not even experienced opinions. Try it, disprove it, and then present your findings. Then you will gain respect for at least having tried. KE0VH Reply to a comment by : KE4SKY on 2002-08-20 I sure hope that Osama Bin Laden and Sadam Hussein's armies use this antenna... This sounds like the Smoketron to me! Reply to a comment by : AB7RG on 2002-08-20 WO5I hit the nail on the head... While I too am very skeptical of this antenna design I won't rule it out until I've tried it. (For those moaning about there being a link to sell these antennas on their sites, does this antenna look that hard to build???) It might be a fun project and would make for a great traveling antenna. It certainly wouldn't be hard or expensive to build! Anyway, as Amateur Radio operators we MUST try to experiment and be able to look at different (and sometimes radical) new ideas, even on old tried and proven concepts. And what if this antenna design does help out those in CC&R neighborhoods, even if it doesn't work like a yagi? Hey we need those guys on the air too! I think that in the interest of furthering the radio art and for scientific experimentation that we should not ever discount something before we try it. After all, what if Marconi had listened to the scientists and so-called experts of his day? After all, radio was "useless" and would be line of sight, at best. Marconi dared to dream and was brave enough to experiment. I hope that as Amateur Radio operators that we can continue to have an open mind towards experimentation and be able to continue to further the radio art. 73 Clinton AB7RG "The important thing is not to stop questioning." -- Albert Einstein | ||
| KE4SKY | 2002-08-20 | |
|---|---|---|
| RE: Small EH Antenna | ||
| I sure hope that Osama Bin Laden and Sadam Hussein's armies use this antenna... This sounds like the Smoketron to me! Reply to a comment by : AB7RG on 2002-08-20 WO5I hit the nail on the head... While I too am very skeptical of this antenna design I won't rule it out until I've tried it. (For those moaning about there being a link to sell these antennas on their sites, does this antenna look that hard to build???) It might be a fun project and would make for a great traveling antenna. It certainly wouldn't be hard or expensive to build! Anyway, as Amateur Radio operators we MUST try to experiment and be able to look at different (and sometimes radical) new ideas, even on old tried and proven concepts. And what if this antenna design does help out those in CC&R neighborhoods, even if it doesn't work like a yagi? Hey we need those guys on the air too! I think that in the interest of furthering the radio art and for scientific experimentation that we should not ever discount something before we try it. After all, what if Marconi had listened to the scientists and so-called experts of his day? After all, radio was "useless" and would be line of sight, at best. Marconi dared to dream and was brave enough to experiment. I hope that as Amateur Radio operators that we can continue to have an open mind towards experimentation and be able to continue to further the radio art. 73 Clinton AB7RG "The important thing is not to stop questioning." -- Albert Einstein | ||
| KG6AMW | 2002-08-20 | |
|---|---|---|
| Small EH Antenna | ||
| Dick, I've seen some off color comments, but they don't seem ill tempered. Its the way a discussion goes. Some believe it, some don't, and some want more evidence. Until you obtain data in a controlled environment and put it into a report, all we have are just comments. Merrill | ||
| AB7RG | 2002-08-20 | |
|---|---|---|
| Small EH Antenna | ||
WO5I hit the nail on the head... While I too am very skeptical of this antenna design I won't rule it out until I've tried it. (For those moaning about there being a link to sell these antennas on their sites, does this antenna look that hard to build???) It might be a fun project and would make for a great traveling antenna. It certainly wouldn't be hard or expensive to build! Anyway, as Amateur Radio operators we MUST try to experiment and be able to look at different (and sometimes radical) new ideas, even on old tried and proven concepts. And what if this antenna design does help out those in CC&R neighborhoods, even if it doesn't work like a yagi? Hey we need those guys on the air too! I think that in the interest of furthering the radio art and for scientific experimentation that we should not ever discount something before we try it. After all, what if Marconi had listened to the scientists and so-called experts of his day? After all, radio was "useless" and would be line of sight, at best. Marconi dared to dream and was brave enough to experiment. I hope that as Amateur Radio operators that we can continue to have an open mind towards experimentation and be able to continue to further the radio art. 73 Clinton AB7RG "The important thing is not to stop questioning." -- Albert Einstein | ||
| W3DCG | 2002-08-20 | |
|---|---|---|
| RE: Small EH Antenna | ||
| Well... In 1980, didn't the idea of CPU speeds in the range of Gigahertz seem Far Out? If you would have told me then, that in 20 years, children will be burning their own CDs, not only I, but likely most of you would be saying, "...burning, as in, on fire- what? You mean riots, our children will be burning our cities?" Or something similar. I mean, my rig uses a PTO- how long has that been completely OUT. How long ago did the first Trans-Oceanic flight occur? When did the first human reach outer space? I don't know the answers... I heard rumors, that Nikolai Tesla had some very Far Out ideas, probably landing him into a lot of hot water, because if they worked, the power structure of civilization might have crumbled. Sure, I'm a skeptic, and have been known by a handful of people to be intensely cynical from time to time. Yeah... antenna theory then and now is basically still the same, based upon the Laws of Physics as they are currently known and taught. Remember when Cell Phones were relatively gigantic, with the telescoping whips, ha! Remember when it was the big status symbol, and now, they are common-place. I know a few people who HAVE NO LANDLINE, but they have a cell phone. Now if you want it bad enough, you can surf via some cell phones. Recall when surfing was all about beaches, waves, and hydrodynamic low-drag boards. The scent of coconut suntan oil... Place the latest Notebook (remember when they were called Lap Tops, now they are called NOTE BOOKS), set the latest Notebook next to a TRS 80, Commadore 64, PETs, audio cassette tape drives...what ever happened to ZIP drives, was that a FLASH IN THE PAN or what? Rendered completely useless by ever faster, higher capacity hard-drives, and now we're at Read/Write CD drives. I am skeptical, but willing to admit, that new discoveries are probable, and that science/research is in bed with industry- and so the struggle for power is the same as it ever was. I for one would be very sad to see towers and the precise, gorgeous, metalic structures that adorn them become obsolete before I ever get the chance to have one such sculpture myself. I'm keeping an Open Mind- it's all I can do in my ignorance. I would imagine, that the developers of such a "crazy" far out paradigm, may very well have a fairly in depth understanding and grasp- of currently known and widely accepted, field-proven antenna design theory. And it so happens, that I derive some small amount of twisted pleasure, when what should not work, performs in ways that defy conventionally accepted theory. It just tickles me pink. Wouldn't it be great for the notion of Super Gain to be true, for the Hex Beam to actually work even if most hams don't completely understand precisely why, and for more research on all of that to be conducted. Wouldn't it be great for the Carolina Windom to actually work as well as the makers claim- for the espoused modeled radiation patterns to actually be- a fairly accurate proximity of their true performance. For me it would, since an OCF dipole is all I have! ha. I am aware that it seems, most antenna advancements work within the realms of conventionally accepted scientifically proven theory. Motor driven variable length elements, yielding wide range continuous optimized multiband coverage- one 3 element Yagi-Uda can practically do the job of at least 3, 3 element mono-banders. That is very cool. What next, remote controlled variable boom length? It would be virtually impossible to argue that in theory it does not work as claimed. Literally revolutionary, (motors inside each element turning). And at the same time NOT- (Only having to rotate the array a maximum of 180 degrees for 360 degree coverage is at best, non revolutionary). That is BEYOND cool, and simply- awsome. It is often human nature to be skeptical, even zealously critical, of new and crazy- preposterous ideas. It means having to learn more and for some people like me, it will take years to attain a solid grasp of current complex antenna theory- and then along comes some new fangled completely different yet apparently true theory- back to square one- and those that make these discoveries likely will be not so generous in the sharing of any such knowledge. After all they will have earned it the hardest way, having endured the pressure of nay saying antenna theory parias and skeptics at every turn... and it has to be tough, having formulated theory and devised the tests to prove or disprove the theory- what if they theory is proven wrong? If proven right? There'll be much profit to gain with such knowledge. Human nature will never stop delving, never stop trying to improve upon that which is already the ultimate. Some people are compelled to keep dreaming, and the quest for a better mouse trap will never end...and I'll bet, that when someone has created the most perfect mouse trap beyong compare, it will be a matter of time before it is once again, improved- beyond compare. Speaking of Surfing, how about that "new" Cheryl Crow video. I'm talking about that VW Van, and the pretty waterfall... and the *acoustic* guitar, and the *lyrics* are okay, too ;) Cheers. Reply to a comment by : KF9Z on 2002-08-19 Folks, you don't get something for nothing. The law of physics can not be changed in order to make something look better than it is. The old saying 'If it's to good to be true...it is' and that is true in this case as well. | ||
| WO5I | 2002-08-20 | |
|---|---|---|
| Small EH Antenna | ||
| Folks, I am not a physicist or even an electrical engineer. But I am open-minded enough to NOT go disparaging the EH theory or design until I've tried it myself. I've seen several articles and web sites publishing results of experiments. Many of those results are favorable. For me to poo-poo it would be tantamount to me calling those hams, who I know nothing good or bad about, liars. Consider: Until Copernicus, the world thought the Earth was the center of the entire universe, and to openly state otherwise was a severe blaspheme, Until Columbus, the earth was thought to be flat (good for propagation, BAD for sailing!), Until Yager, the sound barrier was just that-- a barrier. Until Armstrong, et al, few really thought that there'd ever be a man on the moon (and probably some of the naysayers still think that all took place on a Hollywood soundstage). My challenge to the ham community that would write this idea off is this: build one yourself, per the directions on any of the published websites. They aren't expensive, they don't take any serious skill or expensive tools. The require a little patience to tune and fine-tune, but once it resonates, you can try it out head-to-head with any antenna you would otherwise use. I intend to put my money where my mouth is and build one. I might find I've wasted my time, then I will take my "I-told-you-so's" like a man. But then again, there are those that think of ham radio in general as one big waste of time! After all, isn't ham radio chock-full of people that experiment? Maybe the EH is a better mousetrap. | ||
| AA5CH | 2002-08-20 | |
|---|---|---|
| RE: Small EH Antenna | ||
| Recently, eHam.net provided a link to a website concerning an EH antenna for 160 meters... http://www.qsl.net/iz7ath/web/02_brew/18_eh/index.htm I'm not smart enough to know if someone is attempting to rewrite the laws of physics with this technology or not...it is an interesting read, nonetheless. 73, Brad AA5CH Reply to a comment by : W7KWS on 2002-08-19 I haven't any idea if this antenna is gobbledygook or not. Many such panacea antennas are just that and nothing more. However, I always try to keep an open mind, inasmuch as a closed mind will reject all new scientific achievements. Those that think that, just because an antenna isn't huge, that it can’t work should review the small tuned loop antennas used by the U.S. military. Amateur versions are written up in the ARRL Antenna Handbook and are very small yet exhibit nearly 100% efficiency when compared to a full size dipole. AEA made one and so does MFJ. They worked quite well. In the meantime, the inventors of the E H antenna, Maurice C. Hately & Fathi M. Kabbary, or their employer (U.S. Patent No. 5,155,495), sure thought enough of this invention to spend some bucks on a patent attorney and filing fees. I know that many patents aren’t worth the paper they’re written on. But at least reading this one will give you much more insight into this antenna than you probably have now. Take a look. It's on the WEB at the U.S. Patent and Trademark Office. Maybe after some study, we’ll have some better, educated views of this work. The URL is: http://patft.uspto.gov/netahtml/srchnum.htm 73, Bob W7KWS | ||
| W7KWS | 2002-08-19 | |
|---|---|---|
| Small EH Antenna | ||
| I haven't any idea if this antenna is gobbledygook or not. Many such panacea antennas are just that and nothing more. However, I always try to keep an open mind, inasmuch as a closed mind will reject all new scientific achievements. Those that think that, just because an antenna isn't huge, that it can’t work should review the small tuned loop antennas used by the U.S. military. Amateur versions are written up in the ARRL Antenna Handbook and are very small yet exhibit nearly 100% efficiency when compared to a full size dipole. AEA made one and so does MFJ. They worked quite well. In the meantime, the inventors of the E H antenna, Maurice C. Hately & Fathi M. Kabbary, or their employer (U.S. Patent No. 5,155,495), sure thought enough of this invention to spend some bucks on a patent attorney and filing fees. I know that many patents aren’t worth the paper they’re written on. But at least reading this one will give you much more insight into this antenna than you probably have now. Take a look. It's on the WEB at the U.S. Patent and Trademark Office. Maybe after some study, we’ll have some better, educated views of this work. The URL is: http://patft.uspto.gov/netahtml/srchnum.htm 73, Bob W7KWS | ||
| WA4DOU | 2002-08-19 | |
|---|---|---|
| RE: Small EH Antenna | ||
| For some strange reason, no amount of feedback, no matter how well reasoned and in harmony with the laws of physics and reality, can debunk this kind of stuff in the minds of those that long for, wish for and by golly are going to have their nothing antenna. Remember this, if it weren't for the simple phenomonon of "feedline radiation", these antennas would not perform at all. Buy some antenna books, read and study them and learn antenna theory. You'll be a lot better off. Reply to a comment by : W4CNG on 2002-08-19 Smoke and Mirrors, Articles all, BUT in the world of communications nothing beats the full length dipole antenna as the standard of measurement on an antenna range. Let's go to the range where the truth is most often extracted (minus advertising hype). Let's also apply EIA RS329 the standard of measurement for gain against the reference dipole to the subject in hand. That should not be very difficult for such a small radiator of RF. | ||
| W4CNG | 2002-08-19 | |
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| Small EH Antenna | ||
| Smoke and Mirrors, Articles all, BUT in the world of communications nothing beats the full length dipole antenna as the standard of measurement on an antenna range. Let's go to the range where the truth is most often extracted (minus advertising hype). Let's also apply EIA RS329 the standard of measurement for gain against the reference dipole to the subject in hand. That should not be very difficult for such a small radiator of RF. | ||
| W4WNT | 2002-08-19 | |
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| Small EH Antenna | ||
| Before we all blow off this idea, remember that there are folks who live in CC&R areas that are looking for working small antennas. While they may never beat a triband beam at 100 feet, these things look like a great possibility for a back porch antenna lifted up with some suitable support. And they are simple enough to build yourself! Meanwhile, I'm looking for a source for the variable capacitors that are used in these antennas. 73, Bill, W4WNT | ||
| AG4DG | 2002-08-19 | |
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| Small EH Antenna | ||
| I'll believe in the EH antenna when it eats into sales of Bugcatcher, Screwdriver, Hamstick, Hustler, Isotron, Isoloop, and other compact/mobile HF antennas. If it's such a great antenna, then why haven't the proponents produced test results and done presentations at IEEE conferences and other technical forums? Remember the efficiency equation: efficiency=Rrad/(Rrad+Rg+Rc) How does the EH antenna maximize radiation resistance and minimize ground and coil/conductive resistance? | ||
| N6AJR | 2002-08-19 | |
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| Small EH Antenna | ||
| Mr. Kurt Sterba, who writes a column for WORLD RADIO magazine states in Septembers issue,pretty much that you can not change the laws of physics no matter how much tin foil you wrap on a toilet paper tube. His final comments are " lets see some actual field tests done on an antenna range against known antennas, ( dipole, 3 ele yagi, etc.) and see if the results are there. The theory is wrong and the antenna appears Not to work as claimed.Until then I will stick with conventional antenna. They do work." Reminds me of the show on unsolved mysteries, where they had a certified psychic back up a expermental ghost hunter as to the effectivness of his new equipment. First , just who certifies psychic's and does it mean anything? and how does infrared heat detectors locate ghosts?? Its like pulling your self off the ground with your own boot straps.. Can't be done..ain't so. and I wasn't born yesterday. By the way if you look up their website on the internet they will be glad to sell you one of these for a small amount of cash... hmmmmmmmmmmm If it looks like poo-poo and smells like poo-poo, I don't have to taste it to make sure.. tom N6AJR | ||
| VE7NGR | 2002-08-19 | |
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| Small EH Antenna | ||
| This same article was posted a few months ago on qrz.com. Lots of interesting discussion ensued - if the topic interests you, you may wish to look it up in the qrz.com archives. | ||
| KF9Z | 2002-08-19 | |
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| Small EH Antenna | ||
| Folks, you don't get something for nothing. The law of physics can not be changed in order to make something look better than it is. The old saying 'If it's to good to be true...it is' and that is true in this case as well. | ||