eHam.net - Amateur Radio (Ham Radio) Community

Call Search
     

New to Ham Radio?
My Profile

Community
Articles
Forums
News
Reviews
Friends Remembered
Strays
Survey Question

Operating
Contesting
DX Cluster Spots
Propagation

Resources
Calendar
Classifieds
Ham Exams
Ham Links
List Archives
News Articles
Product Reviews
QSL Managers

Site Info
eHam Help (FAQ)
Support the site
The eHam Team
Advertising Info
Vision Statement
About eHam.net



[Articles Home]  [Add Article]  

The E-H Antenna Revisited

Steve Katz (WB2WIK) on April 1, 2003
View comments about this article!


The E-H Antenna Revisited

By Steve Katz, WB2WIK/6

0x08 graphic

A recent article on eHam.net, which can be found at http://www.eham.net/articles/3586, by KE0VH, discussed the virtues of the `E-H Antenna.'

Since that article can still be accessed on line, there's no reason to rehash what it said. If you visit the E-H Antenna website, http://www.eh-antenna.com, or a related site, http://www.qsl.net/w0kph/, you'll find more information relating to the theory, design and operation of E-H antennas. Unfortunately, for all its virtues, which I'll summarize here, the E-H isn't much of an antenna.

Having said that, I should also say that it's definitely not a dummy load. It makes contacts, solidly and easily. It's reasonably easy, and inexpensive to build. The only drawbacks I found, operationally, are that within reason and based on the designs provided in the articles, it won't handle a lot of power and the design is single-band in nature. It's a high-Q antenna that won't tolerate multiple band operation, at least not in the form discussed.

Virtues

Very small, very lightweight, very inconspicuous and unobtrusive - a good `stealth' antenna that could be employed almost anywhere, despite antenna restrictions.

Evidently quite efficient. Not to say its performance is on par with a ½-wave dipole - it's definitely not. However, the power applied to it is mostly radiated, as evidenced by the fact that I can run 100W CW to it for an hour and observe almost no component heating, which would be obvious if much of the 100W were dissipated, due to the small size of all the components.

Narrowband, but not so much that it won't cover most of an amateur band. The 20 meter model assembled, tested and shown in this article covered about 150 kHz of the 20 meter band between 2:1 VSWR points. Not so narrowband that it's not useful over the entire band; however, it's narrowband enough to reject out-of-band signals well. (It does, and much better than the typical `wire' antenna - which I find useful.)

Reasonably environmentally stable, for a hi-Q antenna. The model shown, using two mica compression trimmer capacitors for tuning, would drift 100 kHz or so down the band if it got wet, in the rain. When it dried off, it would drift right back up to its originally resonant frequency. I operated it in very hot (100 degree+) weather, and also in cooler (55 degree) weather, and the resonant frequency did not notably change. (I did not try sub-freezing weather.)

Best of all, the damned thing made contacts. Lots of them. I'll discuss that more in a moment, but making contacts is what it's all about, and the E-H can do it.

What's not great

Well, it's not a panacea. If I had to choose between having no antenna or having the E-H, the decision's clear. But, if I had to choose between having the E-H or having a ½-wave dipole, or a good vertical, that decision would also be clear, and the E-H would not be the choice.

Also, being a hi-Q, single-band antenna design, for anyone who wants to work a bunch of bands, they'll need a bunch of E-H's. Of course, the Bilal Isotron antenna (http://www.rayfield.net/isotron), which is amazingly similar operationally to the E-H, has the same problem: If you want to work four bands, you need four antennas. People seem to do that.

And, don't be tempted to `QRO' with this antenna. The breakdown voltage rating of even mica compression trimmers isn't sufficient to run much more than 100W of power to this antenna. I suppose the antenna could be redesigned using much larger, heavier components to accommodate higher power, but then the advantages of small, lightweight, easy and inexpensive to build are lost.

The test

The antenna shown was borrowed from Dave, KD3V, in Hollywood, CA. He already had one that he said worked well, so rather than start from scratch building one, I simply borrowed his (thanks, Dave) for a period of weeks. Dave didn't build this antenna, he just loaned it to me; it was actually constructed by Ivo, WA6SUA, evidently for Bob, KL7EAL, who is its rightful owner. This particular unit is beautifully done, obviously by someone technically talented, using premium materials. The cylindrical radiators are copper tubing, the inductors are Teflon-insulated wire, and the trimmer capacitors are high-quality mica compression units, as recommended by W0KPH.

0x08 graphic
Figure 1: The E-H construction, close up. Ivo did a beautiful job, and I doubt anyone could do much better.

The most important tests were the `on-the-air' ones performed mostly in October and November 2002. Hundreds of contacts were made from my station on 20 meters, CW and SSB, over paths ranging from direct wave (2-3 miles) to long-path F2 propagation at distances of more than 10,000 miles. In all cases, I had other antennas to compare to, instantly. The E-H antenna was installed on a non-conductive PVC pipe, as recommended by the articles, and placed 20 feet above ground on the roof of my home. Its feedline, about 20' of RG58A/U connected to 80' of high-quality RG8X coax (International 9092, about the best RG8X on the market), went to one port of my Alpha-Delta coaxial antenna switch. Two other ports of the same switch are connected to my 6 element LPDA beam up 53' on a tower in the backyard; and to a Hustler 6BTV vertical antenna on a roof tower (about 25' above ground at its base, and about 30' away from the E-H installation), with several radials. It takes less than one second to switch between all three antennas, observing signal strength and listening to strength and clarity of any station worked, or even heard.

I'll tabulate the results with some specifics, just for fun. Possibly some reading this article will be in my list of logged contacts, which is too long to reproduce in its entirety.

Overall, here's what happened:

E-H compared with 6BTV vertical: Typically -20 dB (down) from the vertical, on virtually any path - long, short, or between. Kind of amazing. Confirmed the 20 dB delta using a precision attenuator (HP 355D), it's really 20 dB alright. And quite consistently.

E-H compared with Tennadyne T6 6-element LPDA: Typically -30 dB (down) from the beam, dependant upon path, but still amazingly consistent. On some paths, perhaps only -20 dB; on some, up to about -35 dB, but on average, about -30 dB, again confirmed using the 355D precision attenuator (lab calibrated, traceable, +/- 0.2 dB).

Just for fun, I tried using a random-length wire, #18 gauge insulated copper hookup wire, just cut to 65' long and tossed out the ground-floor window, with no tuner or any matching devices of any kind, plugged into the fourth port of the switch using a `banana plug' to terminate the wire and make it fit the center post of an SO-239 connector. The wire and the E-H antenna were frequently neck-in-neck on received signals; however, I had no way to match the wire to make it work for transmitting, so this was a `received signal' test only.

The lab

I brought the antenna to the EMC lab at JMR Electronics Inc. in Chatsworth, CA (http://www.jmr.com) and placed it on the non-conductive rotating test table in the RF anechoic chamber to measure the E-H's radiation pattern and gain referenced to a NIST-traceable standard antenna. A snapshot of the test process and chamber used can be found at http://www.jmr.com/custom/compliance_1.html. This chamber is quite large and is virtually reflection-free from about 100 kHz through 10 GHz, and performs extremely well (like `free space') in the 14 MHz region, so measurements made therein are considered quite accurate by the FCC, CISPR and other agencies. In fact, this particular chamber and test site is NVLAP-accredited and on the FCC list of approved test facilities, of which there are fewer than seventy in all the U.S., last I checked.

Results: As well predicted by actual on-the-air use, the E-H measures between 20 and 22 dB below a 0.5WL dipole* at 14.150 MHz, its resonant frequency, depending upon planar orientation. I rotated the antenna in every possible manner (remotely, using robotic equipment in the chamber) and could not come up with any `amazing' results, no matter what I did. It measures about the way it works, no better, but no worse.

What does this mean?

I'm not sure. I guess it means that if you have a 100W transmitter connected to an E-H antenna in free space, that will perform about a well as a 1W transmitter connected to a ½-wavelength dipole in free space. Sounds like quite a compromise, but then, most people using an E-H probably don't have room or permission to install a ½-wavelength dipole, which, on 20 meters, would be more than 33' long and need to be 33' above ground to work like a dipole.

When one considers the 20 meter E-H is about 0.025 wavelengths long (!), can be made to look like a ventpipe extension, bird feeder or many other acceptable accessories, might cost $10 to $20 to build, and actually makes contacts on the air with reasonable ease, it's a hell of a deal.

In my operating experience, I often started a QSO using one of my regular, larger antennas, then switched to the E-H, logging the difference in signal reports (both ways). I sometimes told my contact what I was doing, and sometimes not. Sometimes I told my contact I was `switching to QRP,' and requested a new signal report, as accurately as they could provide. That 20 dB figure just kept recurring. If I was S9 with the 6BTV vertical, I'd drop to S5-S6 (18 to 24 dB change) with the E-H, if I could trust people's S-meters. I don't trust S-meters in general, so that's why I kept reaffirming with my own S-meter, calibrated by a lab standard attenuator.

In most cases - probably 90% -- the station I contacted with the large vertical or beam continued to hear me with the E-H, although weaker. And I could hear them, too. In about 10% of the cases, the contact would be lost by making the switch to the E-H. Those were the cases where the initial signal just wasn't that strong, and switching to the E-H would drop it into the noise level.

During the ARRL November Sweepstakes (CW), I initiated and completed several contacts on 20m using only the E-H. I think every single station I called came back to me, and we completed the contact - all five seconds of it!

I worked a `big gun' in India, Sabu, VU2ELJ, long-path (over the south pole) on 20m SSB using the E-H and 100W PEP output. Sabu gave me a `56' report. Normally, I work him using a kW and a beam, and I'm S9+. But, you know, 56 is a workable contact, and this guy is on the other side of the world.

Summary

Would I willingly sacrifice 20 dB of signal strength, both transmitted and received? Nope. But would I rather have an E-H antenna than be off the air? Yep, yep, yep!

I subscribe to the “if it was that great, everybody would be using them” theory of product development. And perhaps even more so to the “if it was that great, contesters would be using them” theory, because amateur radio contesters will try anything that provides the slightest operational edge. In the case of the E-H antenna, everybody isn't using them, and I don't know even one contester who is. Clearly, this design is not replacing Hertzian antennas any time soon.

If you want to read about the operational theory, go to the websites referenced earlier. But all that aside, if you want a miniscule antenna that can make global contacts with a bit of operator skill and propagation, try building an E-H. Especially if you can't install a `regular' antenna, due to restrictions. You'll be surprised.

WB2WIK/6

*Note: A 1/2WL 20m dipole isn't required to make this measurement. We use a NIST-traceable calibrated antenna reference standard and correlate data from that.

Contact tabulation

I promised an abbreviated contact tabulation, so here it is! All contacts are on 20m, either CW or SSB as indicated by RST reports:

STN DATE/TIME RS(T) RS(T) NOTES

w/6BTV w/E-H

VE3XAP 10/3 0031 59 55 Sam-Toronto

WO3Z 10/6 0203 599 559 NR 179-PA

KY5R 10/6 0210 59 55 NR 171-AL

AL7ES/7 10/7 0014 59 56 Terry-mobile in WA

W4USR 10/7 2353 589 539 Dennis-NC

N2UI 10/8 0054 599 549 Tom-NM

K1EKF 10/10 0049 59 56 Rich-GA

CO8ZZ 10/18 0121 59 55 Raoul-Cuba

These are very representative of results over a 6-week period. A total of 296 contacts were made with the E-H during that time.

-30-

Member Comments:
This article has expired. No more comments may be added.
 
The E-H Antenna Revisited  
by K8ZO on April 2, 2003 Mail this to a friend!
Great article, Steve. Thanks for all of you effort.

73, Dick
K8ZO
 
RE: The E-H Antenna Revisited  
by W8JI on April 2, 2003 Mail this to a friend!
Great work Steve. Your measurements verify engineering analysis of the antenna, and should help dispell false claims or theories that E-H and CFA antennas have some "unusual" mode of generating E-M radiation.

I have a technical explaination of how the E-H antenna radiates, when efficiency seems to exceed theory, at:

http://www.w8ji.com/e-h_antenna.htm

Very small antennas all suffer quite noticeable efficiency decrease from full size antennas. There is no free lunch or magical form of generating E-M waves.

73 Tom
 
RE: The E-H Antenna Revisited  
by WA4DOU on April 2, 2003 Mail this to a friend!
I'm glad to see this antennas performance finally characterized honestly. Thanks, Steve.
 
The E-H Antenna Revisited  
by KE0VH on April 2, 2003 Mail this to a friend!
Excellent work Steve and the article is great. Basically what I said as far as the performance goes in my article long ago, but with far more work and effort. I just wanted to see the thing work, which it did and your results were about what I had with my test model which is now gathering dust in the garage as I have not had time to work more. Much Much better than being off air. Sharing idea's and not being a know it all critic is why I put my first article about this antenna design up. Not all of us have the room, money, or family tolerance to put up towers, beams, and operate with a kilowatt. This antenna works nicely, and while not as good as other antenna's in some cases, it could fill the bill for some, and is just plain fun to mess around with. Now, I am looking forward to trying the ILA antenna, (Ionic Liquid Antenna), yes, made of PVC filled with salt water. Look it up in a search engine, it really works too.

73' KEVH, www.geocities.com/ke0vh
 
The E-H Antenna Revisited  
by W4CNG on April 2, 2003 Mail this to a friend!
Thanks for the article Steve. You have done a very detailed analysis of the antenna, which is about as close to "Get it out on an antenna Range and measure it against a standard", which was my response to the previous article. I saw one recently at a Ga Hamfest and it seemed to perform fairly well, but there was not a second antenna (dipole or otherwise) to make signal comparasions with, so it was a one sided measurement, yes it could hear and transmit, but you did not know how well it was doing.

 
The E-H Antenna Revisited  
by K8AG on April 2, 2003 Mail this to a friend!
I wonder how well a 160 meter one would do compared to some of the compromise antennas for that band.

John Pawlicki, K8AG
 
excellent article  
by JJ1BDX on April 2, 2003 Mail this to a friend!
Thorough quantative analysis, easy to understand, and objective evaluation. Quite impressed. Nice work.
// Kenji 'Joe' Rikitake, JJ1BDX/3 es K1BDX
 
The E-H Antenna Revisited  
by W3JXP on April 2, 2003 Mail this to a friend!
Now I want to see a comparison to a 100w light bulb on a stick. I bet it would work just as good. By the way two ham stick mobile whips hooked up as a dipole are by my measurements only -10db from a dipole.


John Passaneau, W3JXP
 
RE: The E-H Antenna Revisited  
by WA4DOU on April 2, 2003 Mail this to a friend!
Tom Schiller,N6BT wrote an article for QST that appeared in the summer of 2001(I think), entitled "Anything Works" or something quite close to that. The thrust of the article was that even light bulbs will radiate a little signal.
One can hardly characterize a signal that has been radiated but is 20 db down from a reference antenna like a trap vertical, as having been radiated by an efficient antenna. Quite the contrary. Even in the most hopeless of situations, a fertile imagination and a little trial and error can find a more efficient antenna to construct that can remain clandestine and still do a creditable job. Many attic dipoles would fit this description.
Build one if you like, use it and enjoy yourself. There are more efficient antennas. I still believe that an antenna that radiates a signal that is 20 db down from a reference antenna like a vertical, is properly referred to as an "air cooled dummy load."
 
The E-H Antenna Revisited  
by N6JSX on April 2, 2003 Mail this to a friend!
Steve, Nice info and nice to see someone is actually looking at the effective radiation rather than just THE 50 ohm match. Hope the lab testing didn't set you back to much as those facilities cost a good sum.

I beleive there is a basic flaw in HAMdom's understanding of "effective radiation" in relation to antenna gain vs. 50 ohm impedence. Most HAMs are only focused on the 50 ohm VSWR.
Then there is the subject of antenna tuners faking out the transmitter and NOT adding to the antenna efficeincies/gain.

Wonder what the actual effective radiation of a Motron antennas are or are they just a lot of coil and angled metal loads?
 
The E-H Antenna Revisited  
by K5UJ on April 2, 2003 Mail this to a friend!
A thorough evaluation, especially one for an antenna, is always valuable. Thanks for taking the time and effort to do this--a great service to other hams.
73
Rob
K5UJ
 
The E-H Antenna Revisited  
Anonymous post on April 2, 2003 Mail this to a friend!
This is the dumbest thing I ever saw. If you want an all band antenna with only 3 - 6 db down at the most use a very short piece of wire (about as long as this antenna is tall) and feed it with an AH-4 tuner. Using an "antenna" with 30db loss compared to a dipole is beyond stupid. If you really want an easier alternative use 50 feet of leaky coax terminated in a dummy load and you will probably get more radiation.
Get a life!
 
RE: The E-H Antenna Revisited  
by K5DVW on April 2, 2003 Mail this to a friend!
I have to wonder if when you have this antenna connected to a long coax outside, if the coax isnt radiating more than the antenna? Did you see any evidence of that in your antenna chamber testing?
 
RE: The E-H Antenna Revisited  
by WB2WIK on April 2, 2003 Mail this to a friend!
K5DVW: No obvious indication of line radiation noted. Since the load provided an excellent match within the band where it was used, there's no reason for the line to radiate; however, I did try the two obvious tests:

1. GDO (Millen) set in diode detector mode with 20m coil installed, sensitivity up: Meter pegged when brought within a few feet of the antenna, but didn't indicate anything at all when the coil was run up and down the coaxial cable for several feet.

2. In the chamber, the DUT is the E-H and the probe is a wideband LPDA on an elevatable, rotatable, plane reversible robotic support; detector could be switched to either analog or logarithmic mode. In the log mode, dynamic range of the detector (an HP spectrum analyzer) is very wide, >90 dB. No blips noted as the antenna pointed to anything but the antenna itself. Should have plotted notable blips when the antenna aimed towards the coax running under the table and across the floor if the line was radiating anything measurable.

Thus, I had little doubt that the vast majority of radiation was coming from the antenna itself.

WB2WIK/6
 
RE: The E-H Antenna Revisited  
by N3HKN on April 2, 2003 Mail this to a friend!
Numbers are close to field tests performed and documented on Yahoo EH Group. There the EH was -28db below a 1/4w vertical on a large outdoor antenna range. Extensive docs on test avaialble at the group site.

I would rather install a screwdriver antenna with some stealthy radials than a single band EH which is generally considered to not work except in cases where feedline radiation is in play. Single band antenna over -20db down from a vertical is not a large segment of the hobby. I prefer the 3 band magnetic loop (1meter/side square) I built from 1/2" copper pipe to the EH that almost blew my PC with feedline radiation!. I will claim that a magnetic loop (1 meter square on 15m, 17m, & 14m)is far superior and almost as cheap. $15 4500v air variable (Oceanstate Electronics) and a $12 12v motor to turn it(All Electronics)plus pipe.
Dick N3HKN
 
RE: The E-H Antenna Revisited  
by K9COX on April 2, 2003 Mail this to a friend!
Well done and accurate Steve, but did you really have to post it on April 1st?
 
RE: The E-H Antenna Revisited  
by W8JI on April 3, 2003 Mail this to a friend!
Steve Wrote:
K5DVW: No obvious indication of line radiation noted. Since the load provided an excellent match within the band where it was used, there's no reason for the line to radiate; however, I did try the two obvious tests:

**
A good match or SWR does not mean a feedline will not radiate. Feedline radiation and SWR are not directly related.

Antenna design and construction, feedline grounding, feedline length, and especially feedline positioning around the antenna control feedline radiation.

When we find E-H antennas (and other very small magical antennas) with results even reasonably near full size antennas, we can bet the feedline is a major contributor to radiation.

Myself, If I had limited space, I'd just use two Hamsticks or some other mobile-style antenna. It would be much more efficient than the poor loading and feed system of the E-H antenna.

The "inventor" of this antenna warns to never add baluns or chokes to the feedline, or performance drops off considerably. That indicates his "good results" are the result a radiating feedline, while Steve's very poor results show what the antenna itself actually does.

Contrary to what some are saying, -20 or -30 dBd is NOT an efficient antenna. It is not even fair performance, it is actually poor. 99% to 99.9% power loss is pathetic! Almost anything with even halfway reasonable construction would work many many times better than that!

73 Tom
 
RE: The E-H Antenna Revisited  
by K9FV on April 3, 2003 Mail this to a friend!
Thanks for all the work Steve.. Your article is your usual well thought out and researched approach.

Ken H>
K9FV
 
RE: The E-H Antenna Revisited  
by WB2WIK on April 3, 2003 Mail this to a friend!
Hi Tom (W8JI),

I don't doubt that "good results" are likely due in part or in whole to feedline radiation in some installations. In my particular case, while I made no effort to minimize such radiation, I also made no effort to enhance it in any way. I just let the transmission line drop from the base of the antenna to the roof, and let it lay on the roof about 20 feet, to the edge of the roof, where it dropped down the side of the house and into one of my "shack access" holes drilled through the side wall about 12" above ground.

-20 dB from an elevated Hustler vertical with lots of radials does seem rather poor, however it's about on par with a ~7' tall 20m Hamstick on a tripod using three radials, sitting on the patio behind the house. When I try that, the Hamstick installation is also about 20dB down from the big elevated 6BTV Hustler. So, my general feeling was, "this stinks compared to a real antenna, but it's making contacts and seems to do as well as what many apartment dwellers are able to muster."

There's a company in Italy (I think) marketing commercially built E-H antennas. I have not tried one of those, but in chatting with the guys, they make lots of special provisions in their performance claims: Some of those included that the E-H cannot be installed less than 1/2-wavelength from virtually anything else (!)...so I guess anyone with less than a 33' radius circle of free space surrounding their antenna shouldn't expect it to work. That's 3421 square feet of "free space" that I expect most people tempted to use tiny hidden antennas really don't have.

WB2WIK/6
 
RE: The E-H Antenna Revisited  
by K5ZQ on April 3, 2003 Mail this to a friend!
Where does the energy go if the components do not heat up and the signal is everywhere -20dB to dipole? Thus has to be a dummy load.
 
RE: The E-H Antenna Revisited  
by WB2WIK on April 3, 2003 Mail this to a friend!
K5ZQ: This indicates a poor grasp of how antennas actually work.

If I install a pair of 40 meter dipoles, one at 10' above ground, and one at 100' above ground...and the higher one produces signals 40 dB stronger over a 10,000 mile path -- does that mean the lower one is a dummy load, absorbing all incident power?

Of course not. The higher antenna is working more efficiently by providing stronger far-field signal with less near-field absorption, at a lower radiation angle, all to the benefit of the station trying to hear me 10,000 miles away. But, the lower antenna isn't dissipating any power.

A dipole installed 1 wavelength above good reflective ground can have "6 dB gain over a dipole," even though it is, itself, a dipole. This occurs from ground gain, radiated signal enhancement created by excellent placement of the antenna. Remember, the reference "dBd" is presumed to mean a dipole in free space, with no ground reflection enhancement.

WB2WIK/6
 
RE: The E-H Antenna Revisited  
by K5ZQ on April 3, 2003 Mail this to a friend!
Well, I my have a poor grasp of antennas, but I would suggest you may want to examine the theory of the integral of the Poynting vector over the entire antenna pattern in 3-space, and see what that has to do with the conservation of energy. If the E-H antenna is down at all angles in 3-space by 20dB in the test chamber as you claim, then it is absorbing a lot of energy someplace.

By the way, you did not explain where the energy was going in you smart-axx answer?

Thanks..Bill
 
RE: The E-H Antenna Revisited  
by WB2WIK on April 3, 2003 Mail this to a friend!
I'd be happy to debate this with you one on one, OM. I fail to see how the Poynting vector, or 3-space, relates to near-field measurement in the anechoic chamber (Rff = 2D*D/WL).

Isn't radiation effectiveness a function of antenna aperture, with the more, the better? Seems to me that Pd = PtGt/4piR*R last I heard. That one antenna has a miniscule aperture compared with another one does not imply the first is dissipating energy -- does it?

WB2WIK/6
 
Real competition of E-H antenna  
by AG4DG on April 3, 2003 Mail this to a friend!
Thanks for the experiments. It would help to try another experiment in which you use RF chokes to minimize feedline radiation, because feedline radiation is undesired and causes RFI, RF feedback, and other troublesome situations.

How does the E-H antenna compare to Hamsticks, Screwdrivers, Bugcatchers, Isotrons, MFJ loops, and other small HF antennas? Could these more traditional mobile/restricted space antennas become obsolete?
 
RE: Real competition of E-H antenna  
by VA3BRR on April 3, 2003 Mail this to a friend!
AG4DG, I don't think it would help to run tests with chokes to eliminate feedline radiation since Steve has already cleary said that there was no feedline radiation.
Steve I always look for your answers to peoples questions in forums. I find your answers are always complete and you back them up with a formula or a theory that I can read up on. As an engineering student I like to research more and more what is going on.
73 Keep up the good work
Brian VA3BRR
 
RE: The E-H Antenna Revisited  
by N0GV on April 3, 2003 Mail this to a friend!
First allow me to compliment you on a fine test protocol; you really have put this thing through its paces in a controllable fashion....

Second lets look at the situation where the E and H fields are parallel or antiparallel -- you do get energy leaving the antenna but it is doing so as an evanscent wave which dies off exponentially as you move away from the antenna -- it is a near field mode and as a result it DOES NOT CONTRIBUTE to the propagating (far field) wave. This is why the far field is defined to be generally >10 wavelengths away from the radiator....

My general analysis last year (back of the envelope) indicated that I would expect less than 1% radiation efficency based on physical size of the unit -- this is not at all good!

On the other hand the recent GAP's new antenna design insures better E to H field orthogonality and I would expect radiation efficencies on the order of 25-75% as compared with a properly matched half wave dipole.

A CFA is yet another design which uses two amplifiers; one for E-Field Generation and the other for H-Field Generation in proper phase. The orthogonality of the fields in a CFA is accomplished through a delay based matching network and the geometries of the antenna(s) themselves. A CFA is narrow band, as is the GAP's antenna (I call it a quasi CFA) and they require a tunable matching network to be frequency agile, often within a single band!!!

In a dipole the greatest radiation occurs in the inner 2/3 of the length of the dipole -- this is where the E-Field is most nearly parallel to the wire and the H-Field is cylindrically oriented w/r to the wire -- hence they are orthogonal there. Bottom line is the outer 1/3 of the dipole contributes ~25% of the radiated power -- this is why end loaded and center loaded radiators work better than base loaded ones in most applications....

Good Job again!

Thanks,

Grover Larkins
 
RE: The E-H Antenna Revisited  
by VE6XX on April 4, 2003 Mail this to a friend!
Greetings: Thank you Steve for your usual thorough & objective analysis. Jack Belrose, VE2CV, whose bona fides speak for themselves has published his observations regarding this antenna & they parallel your own. Exorbitant claims have been made in favor of this antenna, ALL without the benefit of accepted engineering measurements (comparison field strengths for instance) or test data. Thank you for detailing for us the fact that there is no "cosmic" 160 metre "rubber ducks".
An interesting & informative treatise as usual.

CHEERS! Brian, VE6XX
 
RE: The E-H Antenna Revisited  
by WB2WIK on April 4, 2003 Mail this to a friend!
Interesting comments, Grover -- appreciate that.

It is clear to me that there's no "free lunch," either. However, while antenna practical efficiencies vary a great deal due in part to precisely the effects you discuss, I don't believe that inefficient radiators for traditional Poynting vector electromagnetic propagation, creating useful signals in the far field which we as amateurs desire, are actually dissipating any power or are "dummy loads" as some have stated. They're just inefficient radiators to do the work we'd like them to do.

While the inventors/proponents of the "E-H Antenna" would like us to believe the design has magical properties which cause the E and H fields to combine precisely to create wonderful far-field propagation, I simply couldn't find any evidence of this happening. And that's the reason for this article!

WB2WIK/6
 
RE: The E-H Antenna Revisited  
by AC6IJ on April 4, 2003 Mail this to a friend!
Terrific article Steve, I would love to see what you have to comment on about the Magnetic Loop Antenna..Bill
 
RE: The E-H Antenna Revisited  
by WA4DOU on April 4, 2003 Mail this to a friend!
When the term "air cooled dummyload" is used in referring to very inefficient antennas, its being employed as a figure of speech, usually.
 
RE: The E-H Antenna Revisited  
by WB2WIK on April 4, 2003 Mail this to a friend!
I think this just verifies my long-held contention that no one can ever accurately state how well (or poorly) his antenna works, unless he has something to compare it to.

If I had no reference antennas for comparison, I would have been able to easily claim the E-H "worked great," since virtually every station heard could be contacted with 100W, and I did make some contacts on the other side of the world when using it. But it doesn't "work great," it just works a little bit, and Propagation does the rest!

WB2WIK/6
 
RE: The E-H Antenna Revisited  
by KZ9G on April 5, 2003 Mail this to a friend!
Another fine article, Steve. I'm sure the testing and evaluating must have been fun and interesting.

BTW, I'm also using a Hustler trap vertical with 30 radials in the Seattle area. After being spoiled with Quads and larger yagis in my youth, I find vertical operation in the City a bit disappointing. That being the case, I most likely wouldn't enjoy HF ops if an E-H antenna had to be employed here (given they're 20 dB down).

I won't be losing any sleep (in Seattle) over this antenna...

73 de Steve, KZ9G
Bothell, WA
 
RE: The E-H Antenna Revisited  
by AH7I on April 6, 2003 Mail this to a friend!
Empirical results are nice. Thanks.

Better orthogonality? Orthogonality of E and H fields
does not imply a radio wave.

The E and H COMPONENTS of a radio wave are not
independent entities. They are useful in modeling
radio waves and predicting their behavior.
Mathematical modeling of a radio wave works very well
in terms of these components. Radio waves interact
with other objects in ways which may be described in
terms of one component or the other. They are not
independent components! Take away one, the other goes
with it.

In the mathematical model of a radio wave, choose to
ignore the physics which it describes, and instead
consider the components as independent entities.
THIS IS THE FLY IN THE OINTMENT!!!

Imagine some reactive fields in such a way as to make
them satisfy the mathematics and state that because the
math is satisfied, a radio wave will be generated.
THIS IS THE B.S.!!!

Offer an antenna that is a 'new and wonderful thing'
based upon math divorced from the physics it originally
modeled.
THIS IS THE SNAKE OIL!!!

Give it a catchy name, surround the name with mysticism
in the form of relatively arcane and misapplied math,
and associate the product with others which sell well
and have catchy names.
THIS IS MARKETING!!!
 
RE: Real competition of E-H antenna  
by W8JI on April 7, 2003 Mail this to a friend!
RE: The E-H Antenna Revisited Reply
by WB2WIK on April 3, 2003
I'd be happy to debate this with you one on one, OM. I fail to see how the Poynting vector, or 3-space, relates to near-field measurement in the anechoic chamber (Rff = 2D*D/WL).

Isn't radiation effectiveness a function of antenna aperture, with the more, the better? Seems to me that Pd = PtGt/4piR*R last I heard. That one antenna has a miniscule aperture compared with another one does not imply the first is dissipating energy -- does it?


Hi Steve,

Expanding on what the other fellow said, the energy has to go "somewhere". In this case what does not conduct away as common mode currents (and voltages) on the feedline shield becomes some form of radiation, either heat or electromagnetic. Eventually all power applied does some sort of "work" someplace.

With a physically small antenna it is often undesired work.

The PHYSICAL apeture or spatial dimension has nothing at all to do with reducing radiating efficiency unless a reduction in radiation resistance or increase in loss resistance converts more energy into heat. Without conversion to heat, all of the transmitter power applied to the feedline eventually causes EM radiation.

As a matter of fact the effective aperature of an antenna relates only the frequency and antenna gain. The effective aperature does niot relate at all directly to physical size. For example a 3wl longwire has a smaller "capture area" or aperature than a small two-element Yagi, as long as the yagi has more gain. Add a series resistor to the Yagi elements to reduce gain, and the effective aperature shrinks dramatically!

Poynting vectors work fine with small resistors, light bulbs, and even large antennas. So does conservation of energy.

What often fools us is not quite knowing how to measure something. For example, heat can be spread over a very large area. We can touch any given point and not feel anything warm. We forget about the physical area and the ability of a large physical area to get rid of heat with little temperature rise. Our conclusion can be there is no loss, when there is a great deal of loss or that something is lossy when it really is not lossy at all.

One example is a small core in a balun, it can become so hot you can't touch it yet the power loss can be very low IF the applied power is high and balun surface area is small.

Another example would be touching the shield with our hands and watching for an SWR change or "sniffing" the shield with "EM" probes. We might *think* common mode radiation is low because the shield acts cool for RF, yet radiation could be very high. Small probes, particularly those that use voltage (electric field) sampling, may not indicate much is going on but it the total ampere-feet of physical area that closely controls the amount of NET radiation.

We perturb or measure only a tiny sample of a large system, and observe only a small effect. What we fail to realize is the over area of the small effect is very large, and this results in an accumulated effect that is actually quite significant.

Understand I'm not disageeing with your results, but the most important thing is we learn every thing we can about how such systems work. It will prevent us from falling victim to more of these hoax antennas. It seems that one comes along every year or so.

I'd expect, without significant feedline radiation, the E-H antenna to be 10-20dB (or more) down from a well-designed antenna. This is not because the E-H is physically small, but because the antenna design is extremely poor. It's ironic a system using very poor construction and design is touted as an "ultra-efficient" antenna, and the very things that make it poor are claimed to be "advanced cutting-edge science".

73 Tom
 
Some follow-up questions  
by N0TONE on April 7, 2003 Mail this to a friend!
Steve, thank you for the first well-reasoned study of this antenna that I have ever seen. Very well done.

One comment: A sure way to measure apparent feedline radiation is with a magnetic probe adjacent to the feedline. Or, just snap a bead around the feedline with a single turn of wire, fed to your spectrum analyzer. Lacking that instrumentation, one can make the feedline non-radiating by applying the right amount of ferrite beads at the antenna. One of the reasons that I suspect feedline radiation is because some other E-H antenna reports, which also indictated 20-30dB down, mention that when they use a balun, the performance degredes notably - as much as 50dB down! That suggests that the feedline did much of the radiating

Second comment: In one of your replies you mentioned that this antenna, mounted on the roof of your house, was comparable to a Hamstik with radials on a tripod on your patio - presumably at substantially reduced elevation. To me, that says very bad things about the E-H, that it performs on a par with a known inefficient antenna (20m Hamstik per my chamber measurements loses about 12dB to heat in the coil), mounted at a substantially lower height.

Question:
How would you compare this antenna to the most obvious thing to compare it to? That would be a simple wire, run from a tuner, up to the same height as where you mounted the E-H. For most hams, a 300W MFJ tuner and some #12 gauge wire is a lot less effort than building an E-H. My guess is that the tuner feeding a simple wire to the same height would perform better. Can you make a similar measurement? An end-fed wire to the E-H mounting, against your same comparison antennas?

tnx

AM
 
RE: Some follow-up questions  
by WB2WIK on April 8, 2003 Mail this to a friend!
N0TONE: No, it's too late for me to make any further comparative analysis with the E-H because, as stated in the article, I had to return the E-H antenna to its rightful owner -- which I did, back in November 2002.

I did compare it with a large, known-good vertical at the same height, however: That was my Hustler 6BTV, which, on 20 meters, is a good performer (4 tuned 1/4-wave sloping radials for 20m, and the antenna is installed on the same roof as the E-H was, about 30 feet west of the E-H location). It was to that antenna that the E-H appeared to be -20 dB, rather consistently. I do not imagine that a wire antenna of similar aperture and elevation would work very much differently, although my 6BTV installation consistently outperforms any kind of single wire antenna I've ever used here, when working low-angle DX.

My other reference antenna was a rotary Tennadyne T6 LPDA at 17 meters above ground, and about 60 feet to the west of the E-H. Obviously, not a fair comparison.

The Hamstick/tripod/patio installation is one that is temporary, and I move it about quite a lot: Normally used for camping or other temp/portable exercises. Although it may be a known poor performer, it's pretty typical of what many apartment dwellers are using, so I thought it a valid reference.

WB2WIK/6
 
RE: Some follow-up questions  
by N0TONE on April 8, 2003 Mail this to a friend!
Sure, the typical apt dweller could use that Hamstik on a tripod. For a genuine comparison, the E-H on the same tripod at the same height would have been interesting. Any antenna that has a fundamentally vertical polarization to it is benefited greatly when the feedpoint is raised above ground. My guess is that the Hamstik at the same height as the E-H would have outperformed it by quite a bit!

AM
 
The E-H Antenna Revisited  
by WA6RF on April 9, 2003 Mail this to a friend!
Hi Steve. As you know we are moving to a gate-guarded community where ham is really cosidered "pork". I have spent hours auditioning antennas to get around those sentiments and I have chosen a HiQ style Isotron for 40 and a larger one for 75 meters. As you mentioned it does the job for making contacts. They hear very well and can easily fit into the "rag chew" phase of our hobby however when it comes down to long distance con-tacts one can not "work everything you can hear." From No. Calif, I can hear many stations where they say ya'll but the only way we can make the trip is by boosting the power. In my new home that maybe welcomed by a visit from the Censors however the Isotrons can easily handle a Kw where most other HiQ antennas can not as you have mentioned. That's it my friend and CUL. Best 73 Dick WA6RF
 
The E-H Antenna Revisited  
by AB8PX on April 11, 2003 Mail this to a friend!
I work as an instrument technician. I have plenty of classic education and gobes of real field experience in real tests and measurements. Relabeling engineering units, or inverting them, does not change reality, only it's perception.
Incidentally, all lies are found in labels. If I tell you the truth, and tell you it's the truth, I told you the truth. If I tell you a lie and tell you that it's a lie, I've told you the truth. If I tell you the truth, and tell you that it's a lie, I just lied to you. If I tell you the truth, and tell you it's a lie, I just lied to you.
A ham in Charleston, WV, worked over a hundred countries using a low CW power rig, tuned to a windowscreen as an antenna. I'm sure that a window screen - tuned with a tuner - is most likely 20 db below a tuned dipole, but he still made these contacts.
If the field strength of an antenna cannot be measured by real instruments in real engineering terms, it is unreasonable to mathmatically compare it to anything. Just because something resonates, does not mean that it radiates. For proof of this, build a few tank circuits whose inductors dissipate heat - or buy a dummy load. Even dummy loads look like an antenna - to an SWR meter. I can get perfect loading on my dummy loads - even without a tuner.
And - look up some thermodynamics. If you dump 80 watts into 10 square inches at average thermal dissipation rates, how many degrees above ambient temperature at standard atmospheric conditions - will you observe? Personally, posts about the E-H antenna have afforded me great entertainment.
 
RE: The E-H Antenna Revisited  
by N0TONE on April 11, 2003 Mail this to a friend!
AD8PX,

The gain of anything is a ratio. As you know from your engineering studies, for instance, the gain of an amplifier can be expressed in several ways. There is the transducter power gain, the insertion gain, the matched assumption gain and a few more. However each one of them is a ratio.

Therefore, it is a perfectly valid engineering technique for Steve to have compared the E-H performance to other reproducible antennas. That, of course is the key - the comparison antenna must be reproducible. He did the correct thing by comparing it to other vertically-polarized antennas. Others have compared the vertically-polarized E-H to a horizontal dipole, and that is meaningless, because the vertically-polarized waves interact with the ground reflections completely differently than the horizontally-polarized waves do. Of course, from your engineering studies, you already knew that, so it is a repeat.

Also, what I'm sure you're aware of is that the field strength equipment itself depends on a detecting antenna. That detecting antenna is subject to exactly the same ground-induced variables that the antenna under test is. Therefore, using a field-strength meter is not all that useful. In fact, it's less useful, because near-field measurements will not tell you what you want to know. You MUST measure in the far field, after at least one propagation hop, because what you really want to know is how well the antenna launches power at the take-off angles that are useul on the band in question. So, a DX-based comparison of received signal strength is, by all manner of study, the most valid measurement to make.

Certainly, one can work many countries with a very poor antenna. Tom Schiller, N6BT, wrote his now-famous QST article entitled "anything works" in which he used a light bulb atop a four foot wooden fence post as a comparison antenna. Several months after that article, he used the light bulb as an antenna to enter a contest - and produced a mid-level score, handily beating many hams using "better" antennas. Operating skill has a lot to do with it.

Also, those using window screens, etc, can certainly work DX - but the window of opportunity is much smaller. I have an attic mounted antenna, and if I can hear DX, I can work it. But with my "outdoor" antenna, mounted at about 45 feet (which is just a wire, anyway, not a multi-element beam), 20 meters is never closed, 24 hours a day. Those using compromise antennas have probably never experienced that - 20 meters being open 24 hours a day - they don't even realize that it's true.

DXCC on 10 watts and an attic antenna can be done in a single contest weekend. But the going gets a lot tougher when you're in the 260 country area, and the only chance you have for new countries is to work DXpeditions during the four days that they're on the air, and propagation is poor.

As has been said, though, if you are in a compromise situation, you do the best you can. When my nephew attended college 20 years ago, we came up with what we thought was quite the solution. The apartment he rented was in a very old house with a large wooden front porch. We strung a vertical loop around the front of that porch. The insulated white wire ran up one support post - which was also wrapped with typical New England Ivy - then it was "hidden" under the first course of shingles above the gutter, then down the other support post, hidden in the ivy, then it ran under the trim board at the front edge of the porch. Completely invisible. But this porch was fully 15 stair-steps above the ground, and was two stories high, and ran across the entire front of the house. Therefore, this loop's wire length was a full wavelength at about 8.2 MHz. Not resonant on any ham band, but he managed to land in the top 5 of any CW DX contest he entered while he lived there. From a "stealth" antenna, no less!

So, you try something. Then you take it down and try something else. That's experimentation, and the best way is Steve's well-demonstrated method: compare your two attempts on the far-end with a receiving test.

AM
 
RE: The E-H Antenna Revisited  
by W8JI on April 12, 2003 Mail this to a friend!
Have a peek at this open air test with and without feedline:

http://home.earthlink.net/~calvinf15/_technical/

73 Tom
 
Lose 99% of Your Signal to Heat  
by KQ6XA on April 13, 2003 Mail this to a friend!
It seems that there might be easier ways to lose 99% of your transmit signal to heat.
73---Bonnie KQ6XA
 
The E-H Antenna Revisited  
by AB1AW on April 16, 2003 Mail this to a friend!
One thing I've been trying to understand about the EH antenna (and other similar small antennas like the Bilal Isotron) is what the polarization of the antenna might be. It is easy to visualize the polarization of a full-size vertical or horizontal antenna. Even a circularly polarized antenna can be (sort of) visualized relative to the antenna's physical shape. However, does an antenna that is only 0.2 wavelengths in size and shaped like a couple of cylinders have a linearly polarized signal? The Isotron advertises a "random" polarization pattern (whatever that means). I am wondering what the EH polarization is and if it might be contributing to its poor performance.

I too have an Isotron (80m) and often cannot work a station that I can here (although running only 2 watts may be part of the problem). Sometimes I wonder if the "random" polarization of these types of antennas is part of the fault.

Mike -- AB1AW
 
RE: The E-H Antenna Revisited  
by KA1OGM on April 20, 2003 Mail this to a friend!
AB1AW: Isotrons and EH's are vertically polarized unless you mount them on their sides...

One of the more recent "discoveries" that I've run across with the EH is the higher it's mounted, the better the performance. This makes sense, if the feedline is radiating and one uses a longer feedline. I haven't gotten that phenomenon myself, however.

The "magical" part of the EH continues to elude, along with the claims about the CFA. I've experimented with the two cylinder and a coil "short, fat dipole" variant to some extent, and I find the results to be sometimes curious, and sometimes banal. The generally found -6 to -20db performance results are what I have found, as well. It's difficult to truly obtain any kind of "scientific" result when playing around with this antenna as a hobbyist, however.

Perhaps there is some unknown phenomenon that will someday be properly quantified along these lines, but after a couple of years of on again, off again hobbyist level experimentation, my conclusion is that the two cylinder and a coil "short, fat dipole" design has been fun to experiment with, and is probably worth trying out if you live somewhere without a yard or a roof to work with.

As an indoor antenna, it's the smallest "workable" thing I've ever tried. There does seem to be something going on with the "near field vs. far field" claims that have been made, but I certainly have no expertise in defining what that might be. Using a compact loop, a mobile with a counterpoise, or any other compact antenna design indoors, in my experience, has always yielded much poorer results than the little "can" antennas I've built and tried out over the past couple of years.

In the final analysis, of course, a full sized outdoor antenna is always going to be much more rewarding.

If you're stuck in an apartment or a condo, however, the EH or the "short, fat dipole" is a viable alternative for HF operation.

Jeff
KA1OGM
 
RE: The E-H Antenna Revisited  
by KC7YRN on July 17, 2003 Mail this to a friend!
>less near-field absorption

Steve,

Great article. I come here to learn, and I appreciate benefiting from your hard work.

I too am wondering about the energy budget. Your on-the-air measurements showed the the transmitter's power was not being radiated from the antenna. Your work in the test chamber suggested it wasn't being radiated from the feedline. Your observation that the antenna wasn't heating up seems to mean the power wasn't being dissipated in the antenna components.

That leaves dissipation in the feedline, dissipation in the matching network, dissipation in nearby objects, and dissipation in the ground. Any others?

Which do you think it is?

73 de Fred KC7YRN

 
RE: The E-H Antenna Revisited  
by KG5JJ on January 10, 2004 Mail this to a friend!
Heh-heh. Years ago, I worked (inadvertently) K5AS, who was several miles away while testing my TS-430 on 20 meters into a Cantenna dummy load. This on 20 meters with high noise levels from DX stations in the fray, and I wasn't running much power.

Even dummy loads radiate a surprising amount of power.

The whole point of this (if there is one) is that anything can be made to radiate power, but there is no substitute for full antenna aperture at proper heights.

Everything else is just playing "catch-up". ;-}

73 KG5JJ (Mike)
 
RE: The E-H Antenna Revisited  
by NS6Y_ on May 4, 2006 Mail this to a friend!
That ain't Teflon wire on that thing either, it's regular old hardware store house wiring wire.
 
RE: The E-H Antenna Revisited  
by K8MHZ on May 10, 2006 Mail this to a friend!
A great article by Steve!

I live in Michigan. One day while working on my Swan 350 I heard a station in KY coming in, but much weaker than usual. The reason? There was no antenna hooked to my coax. The signal had found a way to use the coax, in my basement no less, as an antenna.

I heard of an engineer in a class he was teaching take two watermelons and match them to an HF rig and actually making contacts with them!

I wonder if two grapes would work on VHF?

73,

Mark K8MHZ

"I heard it through the grapevine"
 
Email Subscription
You are not subscribed to discussions on this article.

Subscribe!
My Subscriptions
Subscriptions Help

Related News & Articles
2-Element Bent Dipole Yagi


Other Antennas Articles
2-Element Bent Dipole Yagi