Highest Gain Discone Antenna Ever
Created by on 2006-05-16Highest gain discone antenna ever, the Parabolic Discone.
This table assumes 1db of illumination loss.
1. Introduction
2. Calculated gain
3. Building a 24 inch Parabolic Discone
4. Stacking
| The Parabolic Discone is a way to achieve incredible omnidirectionalgain with discone bandwidth. The driven element is a discone antennaat the focus of an extended parabolic reflector. The RF is focusedupward by the parabola then deflected sideways by a 45 degree cone reflector. See the ray diagram to the right. In theory the gain is the squareof a typical dish antenna, half the db value I came up with this idea because I like discone antennas but wantedmore gain. Stacking discones into a vertical collinear array is certainto have directivity and bandwidth problems, which does not occur with thisreflector arrangement. An interesting option is to place the defecting cone higher, like aperiscope antenna. |  |
Calculated omnidirectional gains over isotropic for an ideal ParabolicDiscone:
| 18 inch | 3 foot | 6 foot | 12 foot | |
| 440 MHz | . | 5 | 8 | 11 |
| 900 MHz | 5 | 8 | 11 | 14 |
| 1200 MHz | 6 | 9 | 12 | 15 |
| 2.4 GHz | 9 | 12 | 15 | 18 |
| 5.0 GHz | 12 | 15 | 18 | 21 |
| 10 GHz | 15 | 18 | 21 | 24 |
Building a 24 Inch Stressed Parabolic Discone
The pictured two foot wide parabolic discone was constructed out of16 pieces of steel rod covered with aluminum window screening for the parabola. Galvanized sheet steel was used for the overhead cone reflector. The discone element at the focus is made out of wire, cut for a 1200 Mhzlow frequency.
The parabolic section was built on the end of a pipe fitted with a pieceof hardwood dowel inside. Using a drill bit slightly larger thanthe rods, 16 evenly spaced holes were drilled around the pipe one inchfrom the top. Pieces of rod 18 inches long are then stuck into theholes. The rod is 0.078 `'music wire'' from K&S Engineering,# 505 (bought at a toy/hobby store).
A central "mast" made from a fiberglass rod is stuck slightly off centerinto the wood fitted in the pipe. A short piece of PVC pipe is attachedon the fiberglass rod using nylon wire ties, by putting the rod up thoughthe ties and pipe. Fishing line is used to pull each of the steelrods into a parabolic shape by tightening and attaching the line to thepiece of PVC pipe. After tightening all the rods a line was run alongthe outside edge. "Plastic Dip" was used at all the attachment pointsto keep them from slipping.
Aluminum window screening is attached by tightly weaving a thin copperwire between the screening and the rods. The necessary precisionof the resulting parabolic section depends on the gain and highest frequencydesired.
The overhead cone is cut from sheet metal by making a circle with an18 inch radius as long as the intended distance from tip to edge. A notch is cut from the edge to the center then the metal pulled into acone. It is best to practice on a scale model cut from a piece ofpaper first.
Equation to verify the parabolic shape:
y= x2 / ( 4 * focus distance) ==> y= x2/ ( 4 * 3) ==> y= x2 / ( 12 )
This results in (x, y) values of (1, .083), (2, .333), (3, .75), (4,1.333), (5, 2.083), (6, 3), (7, 4.083), (8, 5.333), (9, 6.75), (10, 8.333),(11, 10.083), and (12,12).
I have tested this antenna at 2.4 and 5.8 Ghz and verified over 6dbof gain by checking how far the signal reached before being lost in noise.
Collinear stacking may be an option instead of building larger parabolicdiscones. In theory you could achieve 3 db of gain by stacking twoidentical parabolic discones. I believe this should provide betterresults than stacking regular discones because the radiated waves are already"straighter" over a wider bandwidth.
I have experimented with a set of one foot parabolic discones at 5.8GHz and observed appx. 1 db of gain. My limited results are likelydue to loss and impedance issues in my test setup. I simply splitthe RF from one 50 ohm coax into two equal length 50 ohm coax using a BNC"T" splitter.
More experimentation with stacked parabolic discones may be worth theeffort because of the space savings. A low loss way to drive thestacked antennas may make stacking useful.
For more details see my webpage at HamDomain.com:
http://hamdomain.com/para-discone/
Michael Lake - KD8CIK
| K0RNY | 2006-06-03 | |
|---|---|---|
| RE: Highest Gain Discone Antenna Ever | ||
| Mike, I've been following this thread, and I want to tell you something: I am in roughly the same shape you are in, though not to the degree you are. Your work has been good, certainly more than I would have put into an amateur project. Keep it up. Constructive criticism is great, you have touched interests and brought out fellow hams who have the same enthusiasm. Snide and destructive criticism? Ignore it. Cast it aside. And you give nothing away, if you have something original then I will be glad to pay for it. Someone else is going to take what you have sweated over and line their own pockets with your work. That's the way the world is, period. You got something patentable then there are plenty of people out there who will help you get it patented. Now, carry on, and give 'em hell. If you became injured or ill with this tumor that robbed you of your mobility while you were serving this country and protecting me, then let me know whoever to contact and for what it's worth, I'll tell them to to get off their duffs and give you what you deserve, and be real &^%$ing quick about it. FOX NEWS would just love your story. You wanna talk antennas or just talk: k0rny_1954@yahoo.com 73 Corny Reply to a comment by : AD6ZU on 2006-05-16 Would it be safe to guess that a vertical cross section of the radiation pattern will show a "pancake" like pattern which flattens our more and more as the gain goes up? Thanks for the article. I love to see works by experimenters who share their ideas. 73 AD6ZU | ||
| KB4EMF | 2006-06-03 | |
|---|---|---|
| RE: Highest Gain Discone Antenna Ever | ||
| Don't quit experimenting with your ideas... Any time you post anything on internet, you will likely get all kinds of responses and this site is not an exception. It's amazing what some people will say once they are behind keyboards.... About doing some field tests, since you have the antenna already, why don't you do a quick test by comparing a signal (local repeater?) by just discone radiator alone, and with your reflector and the dish? It should become fairly obvious if your theory is correct. P.S. I have an old book written in the 80s about the history of the Cubic Quad.... This guy did some crazy stuff before finally coming to the current design... including using a toilet parts to lower the Q of the antenna.... Reply to a comment by : KD8CIK on 2006-06-02 The basic principles of the Parabolic Discone are true and based on physics. I never claimed to be a great technical writer. The calculated gains still need to be verified by someone else who honestly understands the theory. I based my figures on the square root of traditional parabolic dish antennas and subtracted 1db for illumination loss. The focal point of the parabola, size of the discone radiating element, and size of the overhead reflecting cone are all variables which need to be optimized. The antenna in this article was the first, and I do not claim that it is the best example of this design! As far as my ‘’lack of effort’’ to better document and verify this design, you need to step into my shoes. I have a hard time concentrating due to symptoms of a significant spinal cord injury. My bladder is usually in pain, feels full when it is not, and spasms like it is turning inside out. To prevent kidney damage I take oxybutynin, imipramine, terazosin, and methenamine mandelate. These drugs along with baclofen appear to be causing me fatigue. (At times I wish I was totally paralyzed so that I would not feel the symptoms.) I am trying to be more active in ham radio locally. Splitting my time up between what I want to do, and taking care of myself, is both depressing and crazy. To find time I end up ignoring issues to the last possible moment. Social Security Disability does not provide me with funds for assistance. I have to take care of my house and life by myself. I am also fighting a loosing battle to find support from the VA. One big motivation for experimenting is to escape all the crazy and depressing issues in my life. I can look at the parabolic discone and be proud of the simple physics. Having something positive to focus on is necessary when your life is otherwise hell. Mike Lake - KD8CIK PS: I called it a Parabolic Discone because it contained a discone in a parabolic reflector. Calling it a ‘’parabolic reflected discone illuminating an overhead cone reflector’’ or similar would be too wordy for practical discussion. G8OTA was calling it the para-discone. Reguardless I still believe that it is ‘’the highest gain omni design the world may ever know having wide bandwidth.’’ | ||
| KD8CIK | 2006-06-02 | |
|---|---|---|
| Highest Gain Discone Antenna Ever | ||
| The basic principles of the Parabolic Discone are true and based on physics. I never claimed to be a great technical writer. The calculated gains still need to be verified by someone else who honestly understands the theory. I based my figures on the square root of traditional parabolic dish antennas and subtracted 1db for illumination loss. The focal point of the parabola, size of the discone radiating element, and size of the overhead reflecting cone are all variables which need to be optimized. The antenna in this article was the first, and I do not claim that it is the best example of this design! As far as my ‘’lack of effort’’ to better document and verify this design, you need to step into my shoes. I have a hard time concentrating due to symptoms of a significant spinal cord injury. My bladder is usually in pain, feels full when it is not, and spasms like it is turning inside out. To prevent kidney damage I take oxybutynin, imipramine, terazosin, and methenamine mandelate. These drugs along with baclofen appear to be causing me fatigue. (At times I wish I was totally paralyzed so that I would not feel the symptoms.) I am trying to be more active in ham radio locally. Splitting my time up between what I want to do, and taking care of myself, is both depressing and crazy. To find time I end up ignoring issues to the last possible moment. Social Security Disability does not provide me with funds for assistance. I have to take care of my house and life by myself. I am also fighting a loosing battle to find support from the VA. One big motivation for experimenting is to escape all the crazy and depressing issues in my life. I can look at the parabolic discone and be proud of the simple physics. Having something positive to focus on is necessary when your life is otherwise hell. Mike Lake - KD8CIK PS: I called it a Parabolic Discone because it contained a discone in a parabolic reflector. Calling it a ‘’parabolic reflected discone illuminating an overhead cone reflector’’ or similar would be too wordy for practical discussion. G8OTA was calling it the para-discone. Reguardless I still believe that it is ‘’the highest gain omni design the world may ever know having wide bandwidth.’’ | ||
| GRETA | 2006-05-30 | |
|---|---|---|
| RE: Highest Gain Discone Antenna Ever | ||
| Yes. Yes! we have seen the secret antennas located up in AK. Why should the govn't have all the fun. I think my 21 db 1/4 wave spike for 2 mtrs is so much better. I can hear a lot of signals that others can't when I put it up on the balloon 200 ft. Only problem is that I have a 26 db loss using the 174U cable to attach to the hand held. Oh and the fact that you have to get 4 of them High Voltage glass insulators off a power pole is a real problem. They go on each leg of the folding chair to keep you from getting zapped. So keep your feet up high if you want to make contacts in the wind. The power company is still looking for who took there insulators off the high line. We told 'em kids!!! They murmered something about 12kv and large charge, see the light. Reply to a comment by : KC8VWM on 2006-05-21 Antenna designs are usually a lightning rod for controversy. That's why I have keep my single all band 21 db. 160 - 6 meter antenna design a secret ovr the years. Reply to a comment by : K8MHZ on 2006-05-21 "If the author had taken the time to measure and REPORT his MEASURED results we wouldn't be wasting our time applauding 'experimentation' IMO." For one thing, I don't consider applauding experimentation a waste of time. However, Chip not only has a point worth considering, he may be able to provide some insight on why the actual performance may not quite be what is expected of this design. I hope Michael follows through with his work and posts the results of actual testing here. No matter if the results are less than spectacular. Or better yet, if they are spectacular. Some time ago in the late 1980's a professer at Boston University came up with the idea that antenna radiators made from pretty geometric shapes, much like children create by cutting designs in folded paper, would be more effecient than pieces of wire or tubing. I just wonder if anyone was surprised when the prof went ahead and proved that the theory worked, and worked well. I also wonder how many 'nay sayers' told him that his idea wouldn't work. Chip, can you enlighten us? I think if you did you would get the undivided attention of the entire thread, most importantly Michael who is undoubtedly interested in creating new ways to harness radio waves. 73, Mark K8MHZ Reply to a comment by : N1IR on 2006-05-20 If the author had taken the time to measure and REPORT his MEASURED results we wouldn't be wasting our time applauding 'experimentation' IMO. Instead, we have model results, based upon faulty assumptions dealing with: aperture and gain; aperture efficiency; discone power patterns and polarization integrity; polarization; near-field; inapplicability of ray tracing to the design shown; illumination; and more. Why should we build one when the author, who obviously has already done so, hasn't, and perhaps can't, reconcile(d) the claims versus the reality? | ||
| FORMER_AB8WD | 2006-05-22 | |
|---|---|---|
| Highest Gain Discone Antenna Ever | ||
| I've been licensed for a little over 7 yrs. now, and my 1st antenna was a discone. Though I must admit, I didn't make it, I bought it at Radio Shack, but it worked well w/ a splitter. I was able to run 6 m., 2 m., 1.25 m. & 70 cm. on it. I think it was a 3 dB gain antenna, but worked well on the tripod on my roof hoisted up 45 ft. in the air. I was a No-Code Tech. at the time, but upgraded to my Tech-Plus within the 1st year. Wow, how does time fly...Awesome article, nice illustrations. -73 Brad. | ||
| KC8VWM | 2006-05-21 | |
|---|---|---|
| RE: Highest Gain Discone Antenna Ever | ||
| Antenna designs are usually a lightning rod for controversy. That's why I have keep my single all band 21 db. 160 - 6 meter antenna design a secret ovr the years. Reply to a comment by : K8MHZ on 2006-05-21 "If the author had taken the time to measure and REPORT his MEASURED results we wouldn't be wasting our time applauding 'experimentation' IMO." For one thing, I don't consider applauding experimentation a waste of time. However, Chip not only has a point worth considering, he may be able to provide some insight on why the actual performance may not quite be what is expected of this design. I hope Michael follows through with his work and posts the results of actual testing here. No matter if the results are less than spectacular. Or better yet, if they are spectacular. Some time ago in the late 1980's a professer at Boston University came up with the idea that antenna radiators made from pretty geometric shapes, much like children create by cutting designs in folded paper, would be more effecient than pieces of wire or tubing. I just wonder if anyone was surprised when the prof went ahead and proved that the theory worked, and worked well. I also wonder how many 'nay sayers' told him that his idea wouldn't work. Chip, can you enlighten us? I think if you did you would get the undivided attention of the entire thread, most importantly Michael who is undoubtedly interested in creating new ways to harness radio waves. 73, Mark K8MHZ Reply to a comment by : N1IR on 2006-05-20 If the author had taken the time to measure and REPORT his MEASURED results we wouldn't be wasting our time applauding 'experimentation' IMO. Instead, we have model results, based upon faulty assumptions dealing with: aperture and gain; aperture efficiency; discone power patterns and polarization integrity; polarization; near-field; inapplicability of ray tracing to the design shown; illumination; and more. Why should we build one when the author, who obviously has already done so, hasn't, and perhaps can't, reconcile(d) the claims versus the reality? | ||
| K8MHZ | 2006-05-21 | |
|---|---|---|
| RE: Highest Gain Discone Antenna Ever | ||
| "If the author had taken the time to measure and REPORT his MEASURED results we wouldn't be wasting our time applauding 'experimentation' IMO." For one thing, I don't consider applauding experimentation a waste of time. However, Chip not only has a point worth considering, he may be able to provide some insight on why the actual performance may not quite be what is expected of this design. I hope Michael follows through with his work and posts the results of actual testing here. No matter if the results are less than spectacular. Or better yet, if they are spectacular. Some time ago in the late 1980's a professer at Boston University came up with the idea that antenna radiators made from pretty geometric shapes, much like children create by cutting designs in folded paper, would be more effecient than pieces of wire or tubing. I just wonder if anyone was surprised when the prof went ahead and proved that the theory worked, and worked well. I also wonder how many 'nay sayers' told him that his idea wouldn't work. Chip, can you enlighten us? I think if you did you would get the undivided attention of the entire thread, most importantly Michael who is undoubtedly interested in creating new ways to harness radio waves. 73, Mark K8MHZ Reply to a comment by : N1IR on 2006-05-20 If the author had taken the time to measure and REPORT his MEASURED results we wouldn't be wasting our time applauding 'experimentation' IMO. Instead, we have model results, based upon faulty assumptions dealing with: aperture and gain; aperture efficiency; discone power patterns and polarization integrity; polarization; near-field; inapplicability of ray tracing to the design shown; illumination; and more. Why should we build one when the author, who obviously has already done so, hasn't, and perhaps can't, reconcile(d) the claims versus the reality? | ||
| K1CJS | 2006-05-20 | |
|---|---|---|
| RE: Highest Gain Discone Antenna Ever | ||
| By W8ZNX on May 17, 2006: "Ahoy Maties highest gain discone antenna ever define gain omnidirectional means in all directions a antenna can not be omnidirectional and have gain at the same time" Oh? I guess all those manufacturers with gain figures on their products (vertical antenna) are full of it? I think not. Your statement is correct for a discone design but wrong for other designs. In the case of this antenna, since it was developed from a discone antenna design, may not have any gain. The reflector unit does reflect the signal in a horizontal pattern but doesn't appear to concentrate vertically sufficiently to get any gain from it. I wonder if it would be better for receiving signals since it does look to concentrate signals to a degree. Anyway, I applaud his efforts. I hope he keeps up experimenting and creating new designs--he may just hit on something! Reply to a comment by : W8ZNX on 2006-05-17 Ahoy Maties highest gain discone antenna ever define gain omnidirectional means in all directions a antenna can not be omnidirectional and have gain at the same time mac | ||
| GRETA | 2006-05-20 | |
|---|---|---|
| RE: Highest Gain Discone Antenna Ever | ||
| Oh! I went to the other web site and their it was. A little disconed antenna down in the bottom. Cuite. Doesn't a discone already have a flat pattern. A biconical emitter might be a better choice than a discone for getting the field out to reflect off the prabola section as well as getting it to the cone. I liked his graphics at the other site. Very nice. Lots of time spent trying to get his idea across. Wonder how the antenna guru Cebik can figure this one out? Has he made any comment as yet? Reply to a comment by : N1IR on 2006-05-20 If the author had taken the time to measure and REPORT his MEASURED results we wouldn't be wasting our time applauding 'experimentation' IMO. Instead, we have model results, based upon faulty assumptions dealing with: aperture and gain; aperture efficiency; discone power patterns and polarization integrity; polarization; near-field; inapplicability of ray tracing to the design shown; illumination; and more. Why should we build one when the author, who obviously has already done so, hasn't, and perhaps can't, reconcile(d) the claims versus the reality? | ||
| N1IR | 2006-05-20 | |
|---|---|---|
| Highest Gain Discone Antenna Ever | ||
| If the author had taken the time to measure and REPORT his MEASURED results we wouldn't be wasting our time applauding 'experimentation' IMO. Instead, we have model results, based upon faulty assumptions dealing with: aperture and gain; aperture efficiency; discone power patterns and polarization integrity; polarization; near-field; inapplicability of ray tracing to the design shown; illumination; and more. Why should we build one when the author, who obviously has already done so, hasn't, and perhaps can't, reconcile(d) the claims versus the reality? | ||
| N1IR | 2006-05-20 | |
|---|---|---|
| Highest Gain Discone Antenna Ever | ||
| But, it is not a discone. It is a contraption that uses a discone as an illuminating feed. But, since the paraboloid is only partially illuminated, and in the near field, the aperture of the paraboloid does not obey the geometric optics assumptions so applied for this contraption. | ||
| K8MHZ | 2006-05-20 | |
|---|---|---|
| RE: Highest Gain Discone Antenna Ever | ||
| Chip, Greta, Did you go to this link? http://hamdomain.com/para-discone/ There is a better view of the inside of the device. The discone is inside the lower reflector, looks to be made from solid wire and indeed does bear the physical characteristics of a discone antenna. This is not quite apparent from just the pictures in the article. 73, Mark K8MHZ Reply to a comment by : N1IR on 2006-05-19 ...and despite what the author claims, this is not a discone. | ||
| N1IR | 2006-05-19 | |
|---|---|---|
| Highest Gain Discone Antenna Ever | ||
| ...and despite what the author claims, this is not a discone. | ||
| N1IR | 2006-05-19 | |
|---|---|---|
| Highest Gain Discone Antenna Ever | ||
| GRETA-- Again: read carefully. The relevant discussion (I had) was with respect to discones and inverted discones--I already commented on this contraption overall. | ||
| GRETA | 2006-05-19 | |
|---|---|---|
| RE: Highest Gain Discone Antenna Ever | ||
| Oh? when the hubbie and I were looking at it again he chuckled and commented that if you took the upside down umbrilla and put it on top of the cone flat, put led's around the outside. Hung it from a piece of filiment fish line and spun it. He thinks the screen would make a whurring noise and would look like a little alien ship hovering in your bedroom. You could take a fuzzy picture of it and call it a UFO intrusion into your house. Titled " The little space aliens answered my CQ on 25 gigs" "We had 'em for dinner--and darn if they really don't taste just like chicken" Why you could photograph a couple of short chicken legs and who would be the wiser. (baked,normal or the KFC's extra crispy) hubbie said somthing about a top that he had as a kid years ago looked jsut like that. Using the imagination yes indeed it looks like something I had seen before. A jelly fish in the BH's swiming upside down. I am sure the writer is not finding humor in this but, hey most discone antennas I have seen have a flat wheel spoked radiator on top and the same number of slopeing rods that form the skirt. If you invert it won't all the signal just fill the bucket? (Hee hee) No - I always thought that the skirt of the discone had the signal on the outside, not the inside, for a field. I asked my friend the antenna guru and he said it wouldn't even be a nice vertical dipole. I don't know about the camera thing. Reply to a comment by : K8MHZ on 2006-05-19 Chip, I see, your reference was to the technique, not the actual device. Since there are many similarities between optics and antennas I can see where the design appears to be workable. It is the differences between light waves and radio waves that may detrimentally affect the expected performance, do you not agree? Hoping you do agree, I am interested in your explanation as to why you feel the antenna won't work. I hope it's better than some of the explanations on why an EH antenna is supposed to work! I would also like to see some of your photo work. I'm good on QRZ if you want to show off a bit. 73, Mark K8MHZ Reply to a comment by : N1IR on 2006-05-19 Mark-- You need to carefully read what I said. Most of your comments have no relevance to my statements. Here is one (of many) such photo adapters for 360 panoramas. Others are more 'tipped' and conical: http://www.0-360.com/ I am a professional photographer, among other things. 73, Chip | ||
| K8MHZ | 2006-05-19 | |
|---|---|---|
| RE: Highest Gain Discone Antenna Ever | ||
| Chip, I see, your reference was to the technique, not the actual device. Since there are many similarities between optics and antennas I can see where the design appears to be workable. It is the differences between light waves and radio waves that may detrimentally affect the expected performance, do you not agree? Hoping you do agree, I am interested in your explanation as to why you feel the antenna won't work. I hope it's better than some of the explanations on why an EH antenna is supposed to work! I would also like to see some of your photo work. I'm good on QRZ if you want to show off a bit. 73, Mark K8MHZ Reply to a comment by : N1IR on 2006-05-19 Mark-- You need to carefully read what I said. Most of your comments have no relevance to my statements. Here is one (of many) such photo adapters for 360 panoramas. Others are more 'tipped' and conical: http://www.0-360.com/ I am a professional photographer, among other things. 73, Chip | ||
| N1IR | 2006-05-19 | |
|---|---|---|
| Highest Gain Discone Antenna Ever | ||
| Mark-- You need to carefully read what I said. Most of your comments have no relevance to my statements. Here is one (of many) such photo adapters for 360 panoramas. Others are more 'tipped' and conical: http://www.0-360.com/ I am a professional photographer, among other things. 73, Chip | ||
| K8MHZ | 2006-05-19 | |
|---|---|---|
| RE: Highest Gain Discone Antenna Ever | ||
| Chip (again) After looking closely at the pic, I see nothing that could be used to provide a panoramic picture. The upper cone is home made of sheet metal. The lower parabolic does resemble a reflector we use for control of a high powered flash unit. (Reflectors diffuse the flash and softens the lines caused by shadows plus other benefits), but does not appear to actually be one as they are flatter and not made of window screen. Special effects image reflectors have to be very smooth to reduce distortions. I seldom use stuff like that as it is too 'gimmicky'. I prefer to use what is part of the shoot, like the back of a headlight on an older DeSoto. Now I'm not a super pro photographer, but I do shoot weddings and portraits and my work has made it to the front cover of QRZ (June 2006). 73, Mark K8MHZ Reply to a comment by : K8MHZ on 2006-05-19 Chip, A reflector can be used with any lens arrangement. Many high end (medium and large format) film cameras are twin lens reflex. Most good shooters can manage to live with the small difference in the images of the two lenses. Is it your feeling that the reflector won't reflect radio waves the same way it reflects light? Perhaps some explanation thereof would be helpful to the designer. My hope is that Michael continues with the experiment in spite of some of the posts here and passes along the results. I know such information is valuable, but here on eHam we hope to get information like this for....a song. 73, Mark K8MHZ Reply to a comment by : N1IR on 2006-05-19 Just want to make it clear again: this antenna does not work as described. Also, photographers are likely to recognize the cone reflector--it is a common and commercially available technique for doing 360 degree panoramas with an SLR. | ||
| K8MHZ | 2006-05-19 | |
|---|---|---|
| RE: Highest Gain Discone Antenna Ever | ||
| Chip, A reflector can be used with any lens arrangement. Many high end (medium and large format) film cameras are twin lens reflex. Most good shooters can manage to live with the small difference in the images of the two lenses. Is it your feeling that the reflector won't reflect radio waves the same way it reflects light? Perhaps some explanation thereof would be helpful to the designer. My hope is that Michael continues with the experiment in spite of some of the posts here and passes along the results. I know such information is valuable, but here on eHam we hope to get information like this for....a song. 73, Mark K8MHZ Reply to a comment by : N1IR on 2006-05-19 Just want to make it clear again: this antenna does not work as described. Also, photographers are likely to recognize the cone reflector--it is a common and commercially available technique for doing 360 degree panoramas with an SLR. | ||
| AB8JC | 2006-05-19 | |
|---|---|---|
| RE: Highest Gain Discone Antenna Ever | ||
| "That is to say, it appears you have been taking lessons from Vito! Alan, KØBG www.k0bg.com " ------------------------- BWAAAAHAHAHAHAHAHAHAHAH AB8JC Reply to a comment by : K0BG on 2006-05-16 I don't consider myself an antenna guru. I leave that up to Tom Rauch, W8JI, and L. B. Cebik, W4RNL, et. al. However, I can say this with certainty; You state "This table assumes 1db of illumination loss." Well, I think the loss is more like 10 dB, and perhaps more. Further, you're assuming the reflective surface of the cone is 100% effective. Quite obviously, it is not. Maybe, it's more like 60% depending on the frequency in question. Although I don't always agree with Mike, K6AER, in this case he's dead on! And when I see the comments from Chip and Steve, I know I'm on the right track. That is to say, it appears you have been taking lessons from Vito! Alan, KØBG www.k0bg.com Reply to a comment by : KV7X on 2006-05-16 Michael, I applaud the work, creativity, and enthusiasm you put into this project. Amateur scientists and inventors have made big contributions to humankind over the years. This project may not be one of them, judging by the critiques posted here, but keep it up! 73, Terry KV7X | ||
| N1IR | 2006-05-19 | |
|---|---|---|
| Highest Gain Discone Antenna Ever | ||
| Just want to make it clear again: this antenna does not work as described. Also, photographers are likely to recognize the cone reflector--it is a common and commercially available technique for doing 360 degree panoramas with an SLR. | ||
| N1IR | 2006-05-19 | |
|---|---|---|
| Highest Gain Discone Antenna Ever | ||
| It's not upside down. This inverted discone arrangement is commonly used for low angle needs. Go build one, stick up high in the air, and measure the elevation pattern for inverted vs non-inverted. Discones are basically wideband monopoles. | ||
| N1IR | 2006-05-19 | |
|---|---|---|
| Highest Gain Discone Antenna Ever | ||
| Someone asked: 'what message are we sending...?!' I agree--it IS a big deal. In the last several years, the perception of the tech community is that ham radio is a 'Land of the Lost' (as one eham member mentioned) and the trend in hams is to be poorly informed--and thus not helpful in providing a skilled pool. Here's the message: in this era of incredible access to information, make some effort to get said information. Also: if you want to scale the 'shoulders' of giants', be sure you don't go barefoot. Hope this helps. | ||
| GRETA | 2006-05-19 | |
|---|---|---|
| RE: Highest Gain Discone Antenna Ever | ||
| I know why it does't work right. Its upside down. Just filp it over top to bottom. If you put the umbrella on the top and the stove cone on the bottom you won't catch as much rain water then. The umbrella will keept he rain off the inside of the cone shaped thing. Any water that then drips down off the outside of the umbrella will be shed away further by the cone section. How do you guys see a discone in that thing? Can you point out where the skirt is to the flat top spokes that make up the discone. Reply to a comment by : AD6ZU on 2006-05-16 Would it be safe to guess that a vertical cross section of the radiation pattern will show a "pancake" like pattern which flattens our more and more as the gain goes up? Thanks for the article. I love to see works by experimenters who share their ideas. 73 AD6ZU | ||
| K0RNY | 2006-05-18 | |
|---|---|---|
| Highest Gain Discone Antenna Ever | ||
| Dude, I rejoice at finding another discone experimenter. I want to offer the disclaimer that I don't hold any degree in electronics as many hams do, nor am I currently employed in the field. I am an AMATEUR radio operator. While many would be quick to jump on various deficeincies they may see in you work, consider all criticism, it just improves the proposition. Antennas are my main interest in ham radio, not DX, not counties, and discones are my specialty within that realm. Your design is sound to me, and is merely the attempt to make a stressed dish reflector more responsive in bandwidth, using the king of all multiband verticals, the discone. The question of gain? As I remember whatever is above a dipole in theoretical free space. Where people look at pseudo-"gain" in the discone is not the amount of signal it throws, but in it's angle of radiation, which, in mine at least, is flat. I have a witnessed 440 band simplex contact at Dayton Hamvention in 1993 of 24 miles with two watts from a Yeasu HT that had a homebuilt discone atop an 8 inch standoff, and people wonder why I love discones so much. Do that with a rubber duck. My own experiments ceased a few years ago through inactivity in radio, I was phasing 2 discones for a measure of directionabilty as the military did and also their work in discone antennas that transmitted outside the "disk's" design size, a 2 meter disk with cone elements for 6 meters resonated with good SWR on 6 meters. Good job and carry on my friend. I hope to find circumstances so that I can construct my long awaited discone for 6 meters this summer. 73 Corny | ||
| KB4EMF | 2006-05-18 | |
|---|---|---|
| RE: Highest Gain Discone Antenna Ever | ||
| Just what kind of message are we sending to the person who took time to experiment and posted his experience, and to all the aspiring new comers? For established hams, it is fairly obvious that the theory behind his claim of high gain has flaws... but not all of us are engineers or ham with 20 years of experience. Most of us had a moment that made us think... hummmmm.... looking at common house hold metals and spent next 5 days perfecting the idea.... He had a good time doing this and is proud of it.... I'm sure he learned alot of things he could have never learned just reading antenna books. Hams are supposed to experiment. We are supposed to share ideas. In addition, this is a hobby, not a profession so not everybody has expertise of the pros. I see nothing wrong with constructive criticizms pointing to the individual with some examples, where he might have gone wrong, so he can continue his quest and improve his next design. But some of you are just ridiculing his effort. This is just shameful. Reply to a comment by : KC8VWM on 2006-05-18 ...Doctor Curmudgeon & Co. Reply to a comment by : N1IR on 2006-05-18 ...geeks from Land of the Lost. | ||
| KC8VWM | 2006-05-18 | |
|---|---|---|
| RE: Highest Gain Discone Antenna Ever | ||
| ...Doctor Curmudgeon & Co. Reply to a comment by : N1IR on 2006-05-18 ...geeks from Land of the Lost. | ||
| N1IR | 2006-05-18 | |
|---|---|---|
| Highest Gain Discone Antenna Ever | ||
| ...geeks from Land of the Lost. | ||
| KC8VWM | 2006-05-18 | |
|---|---|---|
| RE: Highest Gain Discone Antenna Ever | ||
(...Sounds like ZZ top tune "She's Got Legs") He's got antennas... he knows how to turn them. He never bleeds on anyone, cause he knows how to tune them. He lets you wonder, how his transmitter's getin' out.. Antenna waves be burnin' up the air, .. my tubes are turnin' red. Got a backup generator..., I just usin' it instead, it burns up my feedline.., all the way up the top of my antenna masthead. Catch my antenna vibrations.... Would you catch my signals vibrations.... Yeah, it's all right Yeah yeah yeah... it's all right. Reply to a comment by : W8ZNX on 2006-05-18 Webster's New Collegiate Dictionary Omni A combining form meaning all Mac | ||
| W8ZNX | 2006-05-18 | |
|---|---|---|
| Highest Gain Discone Antenna Ever | ||
| Webster's New Collegiate Dictionary Omni A combining form meaning all Mac | ||
| K8MHZ | 2006-05-18 | |
|---|---|---|
| RE: Highest Gain Discone Antenna Ever | ||
| Chip, The donut is a great analogy. To an extent. The problem is that in order to create high gain in a desired azimuth, a null must be created by virtue of the re-location of power. Modeling depicts huge nulls above and below a vertical radiator. In reality, there is considerable weakness at points coaxial to the radiator, but far from a complete null. In real life (if one could call my life real :) ), I have used different VHF antennas. What I found was that a small 'unity gain' antenna 16 inches tall performs about 85 to 95 percent as well as a 'high gain' "5.6 dB" antenna that is 54" long. Since I don't like the 'ungainly' look of the longer antenna, and I can get my Caravan into the garage with the smaller one, I not only use the smaller one but continually question the accuracy of advertised gain. Sure, the numbers work on the computer, but I don't see the same thing in practice. Since both antennas are mag mounted, I predict that if I switch the small antenna mount to a drilled NMO, the small one will easily outperform the larger one. I also have much exposure to commercially installed VHF antennas. The largest I see are 1/4 waves with drilled mounts. I also see some of the Antennex 'stealth' antennas that are about 3 inches tall under a radome being used. I NEVER see loading coils, co-linears, or any of the 'tricks' hams use. This could be due to fragility, but I think there is more to it. Now, to make things even more mind cluttering, the polarity of the wave comes into play. Do gain calculations merely assume that all antennas will have the exact same polar orientation? By playing around with easily movable VHF antennas, I have found that a difference of almost 40 dB can be made by changing the position of the antenna. I have also found that in some cases the best performance is NOT with the antenna perpendicular to the earth as the transmitting antenna is. Modeling presents a 'picture' of a shape that has a surface defined by points of equal signal strengths. The surface takes on a two dimensional form and we measure the energy there in the terms of millivolts/cm(squared). In modeling as long as the antenna is on the surface of the modeled shape it should bring the same signal to it's reciever. My real live experience is that this is very largely dependant upon the angle of the antenna. It also seems to me that the antenna is an almost one dimensional object and not accurately described by two dimensional predictions. Now, with a mind this cluttered, how am I supposed to write decent antenna songs?? 73, Mark K8MHZ Reply to a comment by : KA0GKT on 2006-05-17 The gain of any parabolic or spherical reflector antenna is expressed by the equation: G=(Pi squared x D squared)/ wavelength squared Where D= diameter of the antenna in the same units of measurment as the wavelength and G is in dB over an isotropic source. Most amateur built dish antennas have around a 35% efficiency due to the surface imperfections of the reflector. So, a reflector with a 2-meter aperature would have a gain of 3.18 dBi at 144 MHz Assuming an efficient feed and an efficiency of the reflector of 35% This figure takes into account just the gain of the dish in the direction of the aperature. Your design reduces the signal by spreading it out over 360-degrees. The half-power beamwidth of your antenna can be expressed by the equation: BW= (70x wavelength)/d Where d is the diameter of the dish in the same units as the wavelength. At 144 MHz, the half-power beamwidth of the same 2-meter diameter antenna would be 72.9 degrees assuming an accurate parabola or spherical reflector. Antennas are great projects and wonderful fodder for experimentation. Edison said it best Genius is 10% inspiration and 90% perspiration. You certainly used a lof of both in this experiment. Keep working on antenna projects. They're Educational...(Shhh, don't let anyone know how much fun they are!) 73 DE KAØGKT/7 --Steve Reply to a comment by : KC8VWM on 2006-05-17 Sometimes experimental antenna designs like this one have useful components or characteristics about them that may be useful for designing or improving other similar antenna designs. I feel this antenna might have some of those characteristics. For example I was thinking what would happen if you could adjusted the distance of the cone by adjusting the distance using a motor away and toward the parabolic reflector. 73 Charles - KC8VWM Reply to a comment by : KI4GSF on 2006-05-17 And here I thought Amatuer Radio allowed experimentation for experimentation's sake. I applaud your efforts and look forward to any updates you may post Reply to a comment by : KC8VWM on 2006-05-17 Looking at the design a little closer it appears that the cone might behave in a similar manner as an adjustable beam does on a maglight flashlight. Perhaps the cone only widens the width of the beam eminating from the parabolic reflector. 73 Charles - KC8VWM Reply to a comment by : N1IR on 2006-05-17 Mark-- A good analogy is to consider a very fat donut. Now: squish it a bit--where does the dough go? It used to be making it fat in width, but now it is forced out the sides. That's how you get a gain increase in omniazimuth--but only over a restricted range of elevations. The higher elevations are now much worse. Most of the time all we want is the low elevations, ergo the perceived advantages. 73, Chip | ||
| KA0GKT | 2006-05-17 | |
|---|---|---|
| RE: Highest Gain Discone Antenna Ever | ||
| The gain of any parabolic or spherical reflector antenna is expressed by the equation: G=(Pi squared x D squared)/ wavelength squared Where D= diameter of the antenna in the same units of measurment as the wavelength and G is in dB over an isotropic source. Most amateur built dish antennas have around a 35% efficiency due to the surface imperfections of the reflector. So, a reflector with a 2-meter aperature would have a gain of 3.18 dBi at 144 MHz Assuming an efficient feed and an efficiency of the reflector of 35% This figure takes into account just the gain of the dish in the direction of the aperature. Your design reduces the signal by spreading it out over 360-degrees. The half-power beamwidth of your antenna can be expressed by the equation: BW= (70x wavelength)/d Where d is the diameter of the dish in the same units as the wavelength. At 144 MHz, the half-power beamwidth of the same 2-meter diameter antenna would be 72.9 degrees assuming an accurate parabola or spherical reflector. Antennas are great projects and wonderful fodder for experimentation. Edison said it best Genius is 10% inspiration and 90% perspiration. You certainly used a lof of both in this experiment. Keep working on antenna projects. They're Educational...(Shhh, don't let anyone know how much fun they are!) 73 DE KAØGKT/7 --Steve Reply to a comment by : KC8VWM on 2006-05-17 Sometimes experimental antenna designs like this one have useful components or characteristics about them that may be useful for designing or improving other similar antenna designs. I feel this antenna might have some of those characteristics. For example I was thinking what would happen if you could adjusted the distance of the cone by adjusting the distance using a motor away and toward the parabolic reflector. 73 Charles - KC8VWM Reply to a comment by : KI4GSF on 2006-05-17 And here I thought Amatuer Radio allowed experimentation for experimentation's sake. I applaud your efforts and look forward to any updates you may post Reply to a comment by : KC8VWM on 2006-05-17 Looking at the design a little closer it appears that the cone might behave in a similar manner as an adjustable beam does on a maglight flashlight. Perhaps the cone only widens the width of the beam eminating from the parabolic reflector. 73 Charles - KC8VWM Reply to a comment by : N1IR on 2006-05-17 Mark-- A good analogy is to consider a very fat donut. Now: squish it a bit--where does the dough go? It used to be making it fat in width, but now it is forced out the sides. That's how you get a gain increase in omniazimuth--but only over a restricted range of elevations. The higher elevations are now much worse. Most of the time all we want is the low elevations, ergo the perceived advantages. 73, Chip | ||
| KC8VWM | 2006-05-17 | |
|---|---|---|
| RE: Highest Gain Discone Antenna Ever | ||
| Sometimes experimental antenna designs like this one have useful components or characteristics about them that may be useful for designing or improving other similar antenna designs. I feel this antenna might have some of those characteristics. For example I was thinking what would happen if you could adjusted the distance of the cone by adjusting the distance using a motor away and toward the parabolic reflector. 73 Charles - KC8VWM Reply to a comment by : KI4GSF on 2006-05-17 And here I thought Amatuer Radio allowed experimentation for experimentation's sake. I applaud your efforts and look forward to any updates you may post Reply to a comment by : KC8VWM on 2006-05-17 Looking at the design a little closer it appears that the cone might behave in a similar manner as an adjustable beam does on a maglight flashlight. Perhaps the cone only widens the width of the beam eminating from the parabolic reflector. 73 Charles - KC8VWM Reply to a comment by : N1IR on 2006-05-17 Mark-- A good analogy is to consider a very fat donut. Now: squish it a bit--where does the dough go? It used to be making it fat in width, but now it is forced out the sides. That's how you get a gain increase in omniazimuth--but only over a restricted range of elevations. The higher elevations are now much worse. Most of the time all we want is the low elevations, ergo the perceived advantages. 73, Chip | ||
| KI4GSF | 2006-05-17 | |
|---|---|---|
| RE: Highest Gain Discone Antenna Ever | ||
| And here I thought Amatuer Radio allowed experimentation for experimentation's sake. I applaud your efforts and look forward to any updates you may post Reply to a comment by : KC8VWM on 2006-05-17 Looking at the design a little closer it appears that the cone might behave in a similar manner as an adjustable beam does on a maglight flashlight. Perhaps the cone only widens the width of the beam eminating from the parabolic reflector. 73 Charles - KC8VWM Reply to a comment by : N1IR on 2006-05-17 Mark-- A good analogy is to consider a very fat donut. Now: squish it a bit--where does the dough go? It used to be making it fat in width, but now it is forced out the sides. That's how you get a gain increase in omniazimuth--but only over a restricted range of elevations. The higher elevations are now much worse. Most of the time all we want is the low elevations, ergo the perceived advantages. 73, Chip | ||
| KC8VWM | 2006-05-17 | |
|---|---|---|
| RE: Highest Gain Discone Antenna Ever | ||
| Looking at the design a little closer it appears that the cone might behave in a similar manner as an adjustable beam does on a maglight flashlight. Perhaps the cone only widens the width of the beam eminating from the parabolic reflector. 73 Charles - KC8VWM Reply to a comment by : N1IR on 2006-05-17 Mark-- A good analogy is to consider a very fat donut. Now: squish it a bit--where does the dough go? It used to be making it fat in width, but now it is forced out the sides. That's how you get a gain increase in omniazimuth--but only over a restricted range of elevations. The higher elevations are now much worse. Most of the time all we want is the low elevations, ergo the perceived advantages. 73, Chip | ||
| N1IR | 2006-05-17 | |
|---|---|---|
| Highest Gain Discone Antenna Ever | ||
| Mark-- A good analogy is to consider a very fat donut. Now: squish it a bit--where does the dough go? It used to be making it fat in width, but now it is forced out the sides. That's how you get a gain increase in omniazimuth--but only over a restricted range of elevations. The higher elevations are now much worse. Most of the time all we want is the low elevations, ergo the perceived advantages. 73, Chip | ||
| WHATURNUTS2 | 2006-05-17 | |
|---|---|---|
| RE: Highest Gain Discone Antenna Ever | ||
| Ahhhh I too am not a antenna guru but, something I did notice. Your picture of the antenna shows a Parabolic Discone and a cone on top. At the bottom of the of the bottom of the parabolic element in the center is the emitter. Now if we take the distance from the emitter in wavelengths to the skirts of the Parabolic dish, such as you have drawn in your sketch, they will be at different lengths (as shown in your drawing spacing). Now lets take the length of the wave as it goes upward towards the conic section. Again these lines you have drawn show that some parts of the waves will refract sooner than others. Measure the distance on your drawing from the center of the cone to where they are at the outside of the parabolic to the cone. This then clearly show that where it strikes the conic section for reflection at different times instead of unity. Won't that have a cancelation effect as some will arrive at a leading length (T1) while other will arrive at a longer path lenght (T2). Thus as they then cross (again using your drawing) won't they then be opposite in phase and thus cancel out some of the gain you said you getting. After all this isn't a tube in a vaccum that has emissions from one element to the other. I think its looking a lot like a sprinkler head pattern out on the lawn. Maybe I might be wrong but, I can't see how your going to keep the distances of the wavelengths phases from getting all screwed up and having a loss effect. Vito might want to jump in here and correct us if were wrong. Nice try though. keep up the research work. I have to agreee with the others though -- this is not a discone antenna in a true sense. Reply to a comment by : K8MHZ on 2006-05-17 "Writing song lyrics about them is geeky." I thought you were commenting on Michael's article when you said you wanted to turn the computer off. I can totally understand you not liking my attempt at writing lyrics. Now you can see why I haven't quit my day job! Your clarification on the meaning of the term omnidirectional as most folks use it is certainly prudent. I have difficulty understanding the advertised gain of many 'omnidirectional' antennas. I simply can't see how narrowing the pattern can give that much gain in a 360 degree application. Another thing about gain we aren't always told is that we have to determine a desired direction, angle, etc. in order to realize the desired effects. If our target is not in that direction, gain means nothing. Truly, the only gain that means squat is the gain the station we are working can measure. What good is the rest of it? 73, Mark K8MHZ Reply to a comment by : N1IR on 2006-05-17 ...when people say 'omni' they mean 'omniazimuthal' as opposed to 'isotropic'. | ||
| K8MHZ | 2006-05-17 | |
|---|---|---|
| RE: Highest Gain Discone Antenna Ever | ||
| "Writing song lyrics about them is geeky." I thought you were commenting on Michael's article when you said you wanted to turn the computer off. I can totally understand you not liking my attempt at writing lyrics. Now you can see why I haven't quit my day job! Your clarification on the meaning of the term omnidirectional as most folks use it is certainly prudent. I have difficulty understanding the advertised gain of many 'omnidirectional' antennas. I simply can't see how narrowing the pattern can give that much gain in a 360 degree application. Another thing about gain we aren't always told is that we have to determine a desired direction, angle, etc. in order to realize the desired effects. If our target is not in that direction, gain means nothing. Truly, the only gain that means squat is the gain the station we are working can measure. What good is the rest of it? 73, Mark K8MHZ Reply to a comment by : N1IR on 2006-05-17 ...when people say 'omni' they mean 'omniazimuthal' as opposed to 'isotropic'. | ||
| N1IR | 2006-05-17 | |
|---|---|---|
| Highest Gain Discone Antenna Ever | ||
| ...when people say 'omni' they mean 'omniazimuthal' as opposed to 'isotropic'. | ||
| N1IR | 2006-05-17 | |
|---|---|---|
| Highest Gain Discone Antenna Ever | ||
| Mac-W8ZNX Sure you can Mac. The coverage at higher elevations is less. Hi gain omni's exist. | ||
| KE4ZHN | 2006-05-17 | |
|---|---|---|
| Highest Gain Discone Antenna Ever | ||
| Maybe Im missing something here. All the discone antennas I ever saw had the cone side facing down, not up. Im no antenna engineer but from what I have read the only way to get any usuable gain from a vertical antenna is to focus its radiation pattern lower, towards the horizon. This thing appears to be upside down. | ||
| W8ZNX | 2006-05-17 | |
|---|---|---|
| Highest Gain Discone Antenna Ever | ||
| Ahoy Maties highest gain discone antenna ever define gain omnidirectional means in all directions a antenna can not be omnidirectional and have gain at the same time mac | ||
| KT8K | 2006-05-17 | |
|---|---|---|
| RE: Highest Gain Discone Antenna Ever | ||
| Kudos to Mike KD8CIK! I only hope the performance of this extremely interesting antenna corresponds to its physical beauty. Don't let the nay-sayers slow you down, Mike. Apply the appropriate equipment and bring us back some test results. I am deeply interested in seeing how this antenna performs. Keep up the great work, and thanks much for sharing it with us. (I LOVE this stuff!) 73 & best rx de kt8k - Tim Reply to a comment by : N1IR on 2006-05-17 Jeez... I'm so grateful I learned to come home at night and turn this stuff off.... Reply to a comment by : K8MHZ on 2006-05-17 Home,home on the Range Where the near and the far fields stray Where seldom is heard A discouraging nerd Saying 'Vertical's the only good way' (My apologies to Vito, but I couldn't resist!) 73, Mark K8MHZ Reply to a comment by : KA4KOE on 2006-05-17 Really, the only way to settle all the hubbub is to go to an antenna test range...... "Home, Home, on the range....." "Where the hams and the Someone help me out here. PHILIP Reply to a comment by : KC8VWM on 2006-05-16 The cone reflector seems like it would refract? the signal in the desired onmi directional direction away from the antenna in practice, however I am not so sure if the antenna would be that broadbanded in nature when transmitting. In short,the measured distance the reflector cone distance is located away from the parabolic reflector feedpoint would have to be a a frequency specific distance in order to achieve a decent VSWR when operating on any specified frequency. This is why I am thinking the distance between the cone and the reflector feedpoint would have to be frequency specific in order for it to achieve a good VSWR. Unless I am missing something it also seems that the angle of radiation would change significantly in nature depending on the frequency used because of the conical design shape of the cone. In other words, different frequencies would reflect from the cone at different points, causing different takeoff angles away from the antenna. Interesting design and I can see what your trying to achieve in practice. Now if we can make the theory work, you might actually have something. I enjoyed thinking about this design and how it would work. Thank you and keep up the experimenting. We need more of this sort of thing. 73 Charles - KC8VWM Reply to a comment by : AD6ZU on 2006-05-16 Would it be safe to guess that a vertical cross section of the radiation pattern will show a "pancake" like pattern which flattens our more and more as the gain goes up? Thanks for the article. I love to see works by experimenters who share their ideas. 73 AD6ZU | ||
| N1IR | 2006-05-17 | |
|---|---|---|
| Highest Gain Discone Antenna Ever | ||
| Antennas are fine. Writing song lyrics about them is geeky. Can we move on? 73, Chip | ||
| K8MHZ | 2006-05-17 | |
|---|---|---|
| RE: Highest Gain Discone Antenna Ever | ||
| "I'm so grateful I learned to come home at night and turn this stuff off...." This implies that you only can tolerate eHam at work?? I'm just not sure how to take your statement, Chip. All we is doin' is havin' a good time here watching a new ham do an experiment. As (I think) Edison has been know to assert that there are no failures in research, only experiments that teach us what doesn't work. I would also like to add that over the years I have made a moderate amount of money making things work that I was told would not and fixing things I was told could not be fixed. In this world there are things that are impossible for some, and quite attainable for others. It's music to my ears to hear "Well I'll be damned, he (insert favorite expetive here) did it!" Keep on Truckin' Michael, I like your thirst for knowledge and your handiwork ain't bad either. Chip, I hope you know that I am not just picking on you (if I were I know you would be willing to step up to the plate!). This is aimed at a few of us that would prefer to diminish Michael's efforts. When he is done, HIS information won't be second hand, no matter what the outcome. And it's all gotta start somewhere. 73 and Good Luck Michael, Mark K8MHZ Reply to a comment by : N1IR on 2006-05-17 Jeez... I'm so grateful I learned to come home at night and turn this stuff off.... Reply to a comment by : K8MHZ on 2006-05-17 Home,home on the Range Where the near and the far fields stray Where seldom is heard A discouraging nerd Saying 'Vertical's the only good way' (My apologies to Vito, but I couldn't resist!) 73, Mark K8MHZ Reply to a comment by : KA4KOE on 2006-05-17 Really, the only way to settle all the hubbub is to go to an antenna test range...... "Home, Home, on the range....." "Where the hams and the Someone help me out here. PHILIP Reply to a comment by : KC8VWM on 2006-05-16 The cone reflector seems like it would refract? the signal in the desired onmi directional direction away from the antenna in practice, however I am not so sure if the antenna would be that broadbanded in nature when transmitting. In short,the measured distance the reflector cone distance is located away from the parabolic reflector feedpoint would have to be a a frequency specific distance in order to achieve a decent VSWR when operating on any specified frequency. This is why I am thinking the distance between the cone and the reflector feedpoint would have to be frequency specific in order for it to achieve a good VSWR. Unless I am missing something it also seems that the angle of radiation would change significantly in nature depending on the frequency used because of the conical design shape of the cone. In other words, different frequencies would reflect from the cone at different points, causing different takeoff angles away from the antenna. Interesting design and I can see what your trying to achieve in practice. Now if we can make the theory work, you might actually have something. I enjoyed thinking about this design and how it would work. Thank you and keep up the experimenting. We need more of this sort of thing. 73 Charles - KC8VWM Reply to a comment by : AD6ZU on 2006-05-16 Would it be safe to guess that a vertical cross section of the radiation pattern will show a "pancake" like pattern which flattens our more and more as the gain goes up? Thanks for the article. I love to see works by experimenters who share their ideas. 73 AD6ZU | ||
| N1IR | 2006-05-17 | |
|---|---|---|
| RE: Highest Gain Discone Antenna Ever | ||
| Jeez... I'm so grateful I learned to come home at night and turn this stuff off.... Reply to a comment by : K8MHZ on 2006-05-17 Home,home on the Range Where the near and the far fields stray Where seldom is heard A discouraging nerd Saying 'Vertical's the only good way' (My apologies to Vito, but I couldn't resist!) 73, Mark K8MHZ Reply to a comment by : KA4KOE on 2006-05-17 Really, the only way to settle all the hubbub is to go to an antenna test range...... "Home, Home, on the range....." "Where the hams and the Someone help me out here. PHILIP Reply to a comment by : KC8VWM on 2006-05-16 The cone reflector seems like it would refract? the signal in the desired onmi directional direction away from the antenna in practice, however I am not so sure if the antenna would be that broadbanded in nature when transmitting. In short,the measured distance the reflector cone distance is located away from the parabolic reflector feedpoint would have to be a a frequency specific distance in order to achieve a decent VSWR when operating on any specified frequency. This is why I am thinking the distance between the cone and the reflector feedpoint would have to be frequency specific in order for it to achieve a good VSWR. Unless I am missing something it also seems that the angle of radiation would change significantly in nature depending on the frequency used because of the conical design shape of the cone. In other words, different frequencies would reflect from the cone at different points, causing different takeoff angles away from the antenna. Interesting design and I can see what your trying to achieve in practice. Now if we can make the theory work, you might actually have something. I enjoyed thinking about this design and how it would work. Thank you and keep up the experimenting. We need more of this sort of thing. 73 Charles - KC8VWM Reply to a comment by : AD6ZU on 2006-05-16 Would it be safe to guess that a vertical cross section of the radiation pattern will show a "pancake" like pattern which flattens our more and more as the gain goes up? Thanks for the article. I love to see works by experimenters who share their ideas. 73 AD6ZU | ||
| K8MHZ | 2006-05-17 | |
|---|---|---|
| RE: Highest Gain Discone Antenna Ever | ||
| Home,home on the Range Where the near and the far fields stray Where seldom is heard A discouraging nerd Saying 'Vertical's the only good way' (My apologies to Vito, but I couldn't resist!) 73, Mark K8MHZ Reply to a comment by : KA4KOE on 2006-05-17 Really, the only way to settle all the hubbub is to go to an antenna test range...... "Home, Home, on the range....." "Where the hams and the Someone help me out here. PHILIP Reply to a comment by : KC8VWM on 2006-05-16 The cone reflector seems like it would refract? the signal in the desired onmi directional direction away from the antenna in practice, however I am not so sure if the antenna would be that broadbanded in nature when transmitting. In short,the measured distance the reflector cone distance is located away from the parabolic reflector feedpoint would have to be a a frequency specific distance in order to achieve a decent VSWR when operating on any specified frequency. This is why I am thinking the distance between the cone and the reflector feedpoint would have to be frequency specific in order for it to achieve a good VSWR. Unless I am missing something it also seems that the angle of radiation would change significantly in nature depending on the frequency used because of the conical design shape of the cone. In other words, different frequencies would reflect from the cone at different points, causing different takeoff angles away from the antenna. Interesting design and I can see what your trying to achieve in practice. Now if we can make the theory work, you might actually have something. I enjoyed thinking about this design and how it would work. Thank you and keep up the experimenting. We need more of this sort of thing. 73 Charles - KC8VWM Reply to a comment by : AD6ZU on 2006-05-16 Would it be safe to guess that a vertical cross section of the radiation pattern will show a "pancake" like pattern which flattens our more and more as the gain goes up? Thanks for the article. I love to see works by experimenters who share their ideas. 73 AD6ZU | ||
| KA4KOE | 2006-05-17 | |
|---|---|---|
| RE: Highest Gain Discone Antenna Ever | ||
| Really, the only way to settle all the hubbub is to go to an antenna test range...... "Home, Home, on the range....." "Where the hams and the Someone help me out here. PHILIP Reply to a comment by : KC8VWM on 2006-05-16 The cone reflector seems like it would refract? the signal in the desired onmi directional direction away from the antenna in practice, however I am not so sure if the antenna would be that broadbanded in nature when transmitting. In short,the measured distance the reflector cone distance is located away from the parabolic reflector feedpoint would have to be a a frequency specific distance in order to achieve a decent VSWR when operating on any specified frequency. This is why I am thinking the distance between the cone and the reflector feedpoint would have to be frequency specific in order for it to achieve a good VSWR. Unless I am missing something it also seems that the angle of radiation would change significantly in nature depending on the frequency used because of the conical design shape of the cone. In other words, different frequencies would reflect from the cone at different points, causing different takeoff angles away from the antenna. Interesting design and I can see what your trying to achieve in practice. Now if we can make the theory work, you might actually have something. I enjoyed thinking about this design and how it would work. Thank you and keep up the experimenting. We need more of this sort of thing. 73 Charles - KC8VWM Reply to a comment by : AD6ZU on 2006-05-16 Would it be safe to guess that a vertical cross section of the radiation pattern will show a "pancake" like pattern which flattens our more and more as the gain goes up? Thanks for the article. I love to see works by experimenters who share their ideas. 73 AD6ZU | ||
| KC8VWM | 2006-05-16 | |
|---|---|---|
| RE: Highest Gain Discone Antenna Ever | ||
| The cone reflector seems like it would refract? the signal in the desired onmi directional direction away from the antenna in practice, however I am not so sure if the antenna would be that broadbanded in nature when transmitting. In short,the measured distance the reflector cone distance is located away from the parabolic reflector feedpoint would have to be a a frequency specific distance in order to achieve a decent VSWR when operating on any specified frequency. This is why I am thinking the distance between the cone and the reflector feedpoint would have to be frequency specific in order for it to achieve a good VSWR. Unless I am missing something it also seems that the angle of radiation would change significantly in nature depending on the frequency used because of the conical design shape of the cone. In other words, different frequencies would reflect from the cone at different points, causing different takeoff angles away from the antenna. Interesting design and I can see what your trying to achieve in practice. Now if we can make the theory work, you might actually have something. I enjoyed thinking about this design and how it would work. Thank you and keep up the experimenting. We need more of this sort of thing. 73 Charles - KC8VWM Reply to a comment by : AD6ZU on 2006-05-16 Would it be safe to guess that a vertical cross section of the radiation pattern will show a "pancake" like pattern which flattens our more and more as the gain goes up? Thanks for the article. I love to see works by experimenters who share their ideas. 73 AD6ZU | ||
| N5EAT | 2006-05-16 | |
|---|---|---|
| RE: Highest Gain Discone Antenna Ever | ||
| All it's going to take is a field strength meter applied at various points around the vertical and horizontal axis of this antenna to determine where the power is concentrated. The field strength meter helped me determine why a huge Texas Bugcatcher on a vehicle of mine wouldn't work worth a nickel. It's donut was below the truck -it literally had a take off angle which was below a line parallel to the ground. Not being willing to turn my truck onto it's cab - i went back to a couple of ham sticks... Congrats on the great work. Take some real world measurements and see what you get. Reply to a comment by : AD6ZU on 2006-05-16 Would it be safe to guess that a vertical cross section of the radiation pattern will show a "pancake" like pattern which flattens our more and more as the gain goes up? Thanks for the article. I love to see works by experimenters who share their ideas. 73 AD6ZU | ||
| K0BG | 2006-05-16 | |
|---|---|---|
| RE: Highest Gain Discone Antenna Ever | ||
| I don't consider myself an antenna guru. I leave that up to Tom Rauch, W8JI, and L. B. Cebik, W4RNL, et. al. However, I can say this with certainty; You state "This table assumes 1db of illumination loss." Well, I think the loss is more like 10 dB, and perhaps more. Further, you're assuming the reflective surface of the cone is 100% effective. Quite obviously, it is not. Maybe, it's more like 60% depending on the frequency in question. Although I don't always agree with Mike, K6AER, in this case he's dead on! And when I see the comments from Chip and Steve, I know I'm on the right track. That is to say, it appears you have been taking lessons from Vito! Alan, KØBG www.k0bg.com Reply to a comment by : KV7X on 2006-05-16 Michael, I applaud the work, creativity, and enthusiasm you put into this project. Amateur scientists and inventors have made big contributions to humankind over the years. This project may not be one of them, judging by the critiques posted here, but keep it up! 73, Terry KV7X | ||
| N9ESH | 2006-05-16 | |
|---|---|---|
| Highest Gain Discone Antenna Ever | ||
| You gotta be kidding! | ||
| KV7X | 2006-05-16 | |
|---|---|---|
| Highest Gain Discone Antenna Ever | ||
| Michael, I applaud the work, creativity, and enthusiasm you put into this project. Amateur scientists and inventors have made big contributions to humankind over the years. This project may not be one of them, judging by the critiques posted here, but keep it up! 73, Terry KV7X | ||
| N1IR | 2006-05-16 | |
|---|---|---|
| Highest Gain Discone Antenna Ever | ||
| tHIS IS so WRONG.... Your discone only illuminates a fraction of the paraboloid,and at the lower frequencies is very much in the near field, so your geometric optics analysis does not apply. Among other issues. What you describe, at least in part, is a common trick used in cornucopia antennas, for example. K6AER is far more gracious than I am...read his comments carefully. Wideband feeds are a well-established technology at this point, and there is no benefit to using a discone as you describe. Sorry. | ||
| K9ZF | 2006-05-16 | |
|---|---|---|
| Highest Gain Discone Antenna Ever | ||
| Interesting concept, but I doubt the practicality. Now here is a thought. At 2.3 GHz, the size would be more practical, and might make one heck of a wifi antenna... OK, anyone have plans for a nice colinear 2m verticle, omni? I've seen the "super-J's", but would like go bigger. Let's say something around 10 to 15 feet long... Copper pipe, or Wire inside PVC, or? Let's build something!! 73 Dan -- K9ZF /R no budget Rover ***QRP-l #1269 Check out the Rover Resource Page at: <http://www.qsl.net/n9rla> List Administrator for: InHam+grid-loc+ham-books | ||
| KB4EMF | 2006-05-16 | |
|---|---|---|
| RE: Highest Gain Discone Antenna Ever | ||
| A very intersting idea... but I have one problem with the theory behind it. Antenna of any kind have no gain overall. It doesn't amplify signal in any way. Instead, it focuses energy in to a direction or two. By focusing energy, for limited directions, if your target is in the direction of the focus(foci), you get more energy, thus you achieve gain. So, if you take a highly directional antenna, such as parabola, with high gain, and place a reflector that distributes the focused beam to 360 degrees, you pretty much un-did the gain. It is possible you may have not much gain than a vertical dipole. The only way this antenna can achieve any gain is if the vertical pattern is narrowly focused. By design, the energy coming out of a parabola with radiator at focus will be parallel. This is true regardless of the reflector size. Then if you reflect it by 45 degree plate, then the energy will again by parallel, this time horizontally. by thinking this, bigger the size, won't reflect in more gain. I'm pretty sure, this theory doesn't quite translate to real life. Now, when I say gain, I am not talking about in comparison to isotopic antenna. Any antenna without loss has gain over isotopic antenna as no real antenna can emit evenly to all directions. (just so we are clear) Nevertheless, it's interesting.... I'd be interested in seeing the comparison between your theory and the actual field measurement. You may have something going here.... then you may not. Reply to a comment by : NT4XT on 2006-05-16 Wow. ET Phone Home. ;-) | ||
| NT4XT | 2006-05-16 | |
|---|---|---|
| Highest Gain Discone Antenna Ever | ||
| Wow. ET Phone Home. ;-) | ||
| K1CJS | 2006-05-16 | |
|---|---|---|
| Highest Gain Discone Antenna Ever | ||
| Mike, Did you try making or getting a phasing harness? Although I am not generally knowledgeable about the specifics of a harness for the two meter band, it seems that two equal lengths of 72 ohm co-ax at a certain length (or multiple of) may be used successfully, just as such a method is used for big rig CB antennas. While a 'T' connector may work, if your cable lengths are not equal you won't get the full benefit--just as if the antenna are not spaced properly, you won't get the full benefit. Nice read, however, and food for thought. Thanks! | ||
| WB2WIK | 2006-05-16 | |
|---|---|---|
| RE: Highest Gain Discone Antenna Ever | ||
| Is it April 1st already? Reply to a comment by : KB3FWW on 2006-05-16 Most ideas don't hold water, but it looks like this one would hold water, snow, leaves or anything else that's in the area. | ||
| KB3FWW | 2006-05-16 | |
|---|---|---|
| Highest Gain Discone Antenna Ever | ||
| Most ideas don't hold water, but it looks like this one would hold water, snow, leaves or anything else that's in the area. | ||
| K6AER | 2006-05-16 | |
|---|---|---|
| RE: Highest Gain Discone Antenna Ever | ||
| The parabolic reflector you have depicted is no where near large enough to properly reflect the vertical wave form in a non orthogonal vertical direction to obtain a flat wave front for the second reflector at the lower frequencies. At 450 MHz the reflector will need to be about 25-30 wavelengths. Now if you build the parabolic properly for 450 MHz and higher frequencies the diameter for 450 MHz will be about 11 meters in diameter for any useful reflected gain. Now you have to build the second omni reflector which will also be about 11 meters in diameter while maintaining proper structural rigidity. Antenna parabolic gain is a function of (HPBW=70ë/D) at 450 MHz for an 11 meter dish and an antenna feed efficiency of 30% (on the high side) will yield a gain of about 29 dBi. This is a wave front gain that has to be split into many azimuth directions by your second reflector and will be come fractional in gain in any one direction. The net yield in omni directional gain is lost. Several factors contribute to antenna gain. Beam width compression, the focus of the antenna pattern is what provides gain. Either you focus the pattern in the elevation (E Plane) or in the azimuth (H plane) or both. This is why (I applaud your efforts) you have not found an antenna design like the one you described. Reply to a comment by : WF7A on 2006-05-16 Very clever! I doff my hat to you, Mike. One of my co-workers walked by and said, "What a crazy looking water fountain." Makes you want to throw coins in it, eh? Since the antenna is large for its electrical wavelength, I'd be curious to know what would be the best or ideal stacking dimensions for 2-M and/or 70-CM use. Good job! Rich | ||
| KK4BH | 2006-05-16 | |
|---|---|---|
| Highest Gain Discone Antenna Ever | ||
| Michael, I am far from being a antenna design engineer, but if this design of yours works as good as you say, I hope you don't hesitate too long applying for a patent or somebody else will get rich off of your efforts. 73 Ken KK4BH | ||
| WF7A | 2006-05-16 | |
|---|---|---|
| Highest Gain Discone Antenna Ever | ||
| Very clever! I doff my hat to you, Mike. One of my co-workers walked by and said, "What a crazy looking water fountain." Makes you want to throw coins in it, eh? Since the antenna is large for its electrical wavelength, I'd be curious to know what would be the best or ideal stacking dimensions for 2-M and/or 70-CM use. Good job! Rich | ||
| K8GU | 2006-05-16 | |
|---|---|---|
| RE: Highest Gain Discone Antenna Ever | ||
| I see how the feed works from the web link now. So, my statement about the reflector being shielded is incorrect. I still don't think it's taking the best advantage of the reflector... Reply to a comment by : K8GU on 2006-05-16 While I applaud experimentation, I have I hard time with this antenna from a theoretical standpoint. A discone is the conical dipole version of the groundplane antenna, hence its broad bandwidth. Given a sufficiently-dense groundplane, the parabolic reflector in the present design would be "invisible". (In other words, the feed doesn't take full advantage of the discone's radiation pattern.) I would be curious what the author had in mind for an application. Certainly smaller broadband gain antennas are possible for the frequencies of interest? Reply to a comment by : KB2NAT on 2006-05-16 Good article, good comments, too. I "gained" a lot. Rick | ||
| K8GU | 2006-05-16 | |
|---|---|---|
| RE: Highest Gain Discone Antenna Ever | ||
| While I applaud experimentation, I have I hard time with this antenna from a theoretical standpoint. A discone is the conical dipole version of the groundplane antenna, hence its broad bandwidth. Given a sufficiently-dense groundplane, the parabolic reflector in the present design would be "invisible". (In other words, the feed doesn't take full advantage of the discone's radiation pattern.) I would be curious what the author had in mind for an application. Certainly smaller broadband gain antennas are possible for the frequencies of interest? Reply to a comment by : KB2NAT on 2006-05-16 Good article, good comments, too. I "gained" a lot. Rick | ||
| KB2NAT | 2006-05-16 | |
|---|---|---|
| Highest Gain Discone Antenna Ever | ||
| Good article, good comments, too. I "gained" a lot. Rick | ||
| K5DVW | 2006-05-16 | |
|---|---|---|
| RE: Highest Gain Discone Antenna Ever | ||
| Interesting idea. Do you have more details on the feedpoint and how it's matched and what the VSWR vs frequency looks like? Reply to a comment by : AD6ZU on 2006-05-16 Would it be safe to guess that a vertical cross section of the radiation pattern will show a "pancake" like pattern which flattens our more and more as the gain goes up? Thanks for the article. I love to see works by experimenters who share their ideas. 73 AD6ZU | ||
| AD6ZU | 2006-05-16 | |
|---|---|---|
| Highest Gain Discone Antenna Ever | ||
| Would it be safe to guess that a vertical cross section of the radiation pattern will show a "pancake" like pattern which flattens our more and more as the gain goes up? Thanks for the article. I love to see works by experimenters who share their ideas. 73 AD6ZU | ||
