If you are using linearly polarized yagis, just mount each vertical and separate horizontally about 5-6 feet using an aluminum crossboom. There is no need for non-metallic boom if the crossboom is perpendicular to the plane of polarization. Ideally, the separation would be so that the field of neither antenna were to touch, but practical separation of the field of the higher frequency antenna is sufficient. If you get cross-talk between VHF and UHF it may be and advantage to have one antenna place in the opposite polarization. Then mount each on a 45-degree slant -----/
I use two x-yagis mounte on metallic crossboom. The antennas are mounted in an X----X configuration and both are RHCP with no problem of cross-talk using up to 50w. Preamps are used with both antennas so either mode-UV or VU may be used. My crossboom is about 6-foot long and both antennas have about 18-foot booms.
73 Ed - KL7UW http://www.kl7uw.com/sat.htm for pictures
At 06:38 PM 4/4/2008, Michael A. Tondee wrote:
I used schedule 80 PVC with a large wooden dowel pushed inside for added rigidity. I sealed each end with epoxy. It's been going strong for a couple of years now. I saw your other post about antennas. At present I'm using a four element 2 meter beam and an 11 element 70cm beam in vertical polarization. Both are homebrewed using Ken Britain's "cheap yagi" design. 73, Michael, W4HIJ ----- Original Message ----- From: w0dxz@aol.com To: amsat-bb@amsat.org Sent: Friday, April 04, 2008 10:36 AM Subject: [amsat-bb] cross boom?
In putting together my antenna,?? (144-432)I need something to use as a horizontal- cross? support boom. What would be the best length, and,? what would be the minimum length,,,? would 6? ft separation be OK?? To minimize problems, should I mount one beam horizontal, one vertical? Does it matter which one, is? which way?
I doubt I can find a fiberglas boom locally,,,? what else could I use?? or, where can I order a fiberglas boom?
thanks Bob W0DXZ _______________________________________________ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
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Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb