[amsat-bb] Re: cross boom?
kl7uw at acsalaska.net
Fri Apr 4 20:50:30 PST 2008
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
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.
>----- Original Message -----
>From: <w0dxz at aol.com>
>To: <amsat-bb at 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
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