|Subject:||Re: [TowerTalk] HF Vee Beam Experience?|
|From:||"Rick Stealey" <firstname.lastname@example.org>|
|Date:||Thu, 13 Sep 2007 21:57:03 +0000|
OK, I'll bite. How well does it work I used a rhombic up at KL7AIZ that
I can't resist - let me also ask you, how do you know yours was dynamite? (assuming that means it worked fantastic.) Because you worked stations and they gave a good signal report? Maybe it was really just a mediocre antenna, but you still got good reports, as most of us do when we are being heard, especially if you are in Alaska!! Now if you say you had an A-B switch and compared it real time to a yagi, dipole, whatever, then maybe you really know it was dynamite.
Mine? Well my rhombic worked out just like the model said it would. It had gain comparable to my 3 element beam at 55 feet in A-B tests(the Rhombic was only at 35 ft), and it had substantial f/b. Mine was about 210 ft on a side, 377 down the middle, out of the handbook. I built it for fun, hoping (although the model said otherwise) that it would tear the band up. It didn't. Four poles, lots of wire, lots of tree trimming, open wire line, tuner, terminating resistor, fixed direction, and the end result is no more performance than I got from my 3 element yagi. But in fairness to the Rhombic, it was at a distinct disadvantage at the low height.
It was interesting playing with it with an antenna analyzer and seeing how the input Z varies all over the place with no terminating R, but really settles down when it is terminated.
If anyone uses 4NEC2 I can give them the file for the model I built. It allows you to change lengths, angles etc. and see the effect on the pattern.
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