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Hexbeam Antenna Modeling
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Hexbeam Antenna Modeling
Clifford,
There are two styles of hexbeam: the older design which has a W-shape Driver and a W-shape Reflector, and which I call the "classic" on my web site; and my newer broadband design which has a W-shape Driver and a U-shape Reflector. I found in my lab notebook a 2m version of the broadband style; its dimensions a half-Driver 21"; Reflector 40"; end gap 2.5". I think I assumed wire construction using #14 bare copper. That would give a hexagon radius of 12.5". When I model this with EZNEC I see about 3.8dBd Forward Gain and 19dB F/B with VSWR=1.4. The problem is that the rearward response is very smooth and "well behaved" so probably not much use for DF. If I increase the end gap to 5" the Forward Gain and F/B remain about the same, but the azimuth pattern devlops deep side nulls (38dB) at plus and minus 130 degrees which may be useful. The VSWR deteriorates to 1.8:1. Hopefully that may give you a starting point for experimentation. If I get a chance I'll try some modelling experiments on the classic design also. 73, Steve G3TXQ |
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Hexbeam Antenna Modeling
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Hexbeam Antenna Modeling
On Jun 4, 1:09*pm, "J.B. Wood" wrote:
Hello, Steve, and all. *Steve, I see you also have an informative article that is posted online atwww.antennex.com/preview/Dec507/hexbeam.pdf Yes, that article described the process by which I arrived at the broadband version. Since then there have been a couple of write-ups in the monthly Antenna column of RadioCommunication magazine, and RSGB published the design in their recent book "Building successful HF antennas". You may also have seen Leo's (K4KIO) constructional article in the March edition of QST. All that has generated quite a lot of interest in the antenna. I try to avoid exagerated claims for the design - at the end of the day it's a "compressed" Yagi and performs as such. But it does provide useful directivity over the five bands 20m thru 10m, with a single feedline, in a size which suits those of us that don't have a lot of space. It's also pretty easy to construct from readily-available materials, although a number of folk now supply complete kits, including K4KIO and more recently DX Engineering. 73, Steve G3TXQ |
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Hexbeam Antenna Modeling
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Hexbeam Antenna Modeling
"J.B. Wood" wrote : Thanks for the reply, Steve. As for exaggerated claims, I'd have to give the award to the designers of (and explainers of the "theory" behind) the Crossed-Field Antenna (CFA). (Of course the CFA has been the subject of numerous antenneX articles but I'm not placing yours in that group!) 73s, I guess that you haven't seen info provided by Art on his shoe-box sized 160M thru whatever antenna that has +9 db gain, and a pencil-thin beam of radiated particles. Art's technical expertise beats the crap out of the CFA guys, as HE (Art) improves on Maxwell's and Gauss' equations, too. And all of this from a retired mechanical engineer, working in his backyard! Mike W5CHR Memphis |
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Hexbeam Antenna Modeling
J.B. Wood wrote:
Thanks for the reply, Steve. As for exaggerated claims, I'd have to give the award to the designers of (and explainers of the "theory" behind) the Crossed-Field Antenna (CFA). (Of course the CFA has been the subject of numerous antenneX articles but I'm not placing yours in that group!) 73s, Here's my candidate for the award, embodied in a U.S. patent: http://tinyurl.com/h546u Roy Lewallen, W7EL |
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Hexbeam Antenna Modeling
Roy Lewallen wrote:
J.B. Wood wrote: Thanks for the reply, Steve. As for exaggerated claims, I'd have to give the award to the designers of (and explainers of the "theory" behind) the Crossed-Field Antenna (CFA). (Of course the CFA has been the subject of numerous antenneX articles but I'm not placing yours in that group!) 73s, Here's my candidate for the award, embodied in a U.S. patent: http://tinyurl.com/h546u Roy Lewallen, W7EL This particular antenna has the useful property of enhancing plant growth too.. " It has been observed by the inventor and witnesses that accelerated plant growth can occur using the present invention. " I think David Strom knew what we was writing about. He deserves a beer. |
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