I think it's highly unlikely that your 2 meter beam is actually affecting
your A3 on 20, assuming the booms are lined up with each other and the 2
meter beam is vertically polarized. Even if it's horizontal I wouldnt
expect much coupling to 20, but that could cause some problem on 2 without
additional spacing. There is no component that could be close to
resonance on 20 in the modest length boom on 2 meters. The only possible
scenario I can think of is some combination of feedline/antenna resonance
going on, but that's pretty remote. If you think that might be a problem,
you could try using some ferrite beads appropriate for HF on the 2 meter
feedline near the antenna feed (basically an UN-UN RF Choke). I'll bet
your high SWR is due to some other problem.
However, you are correct in that separation of different antennas systems
is never bad! If you can get it, use it!
73, Tyler K3MM
To: towertalk@contesting.com
cc: (bcc: Tyler G Stewart/BENN/CEC)
Subject: [TowerTalk] spacing of 2 meter and tribander
I have a cushcraft 10 element 2 meter beam 3 feet above my A3s and the 20
meter swr is degraded to approximately to 2:1 instead of 1.2:1. K3MM's
suggestion of the fiberglas mast is excellent and go with as musch spacing
as possible. I have noticed no pattern degradtion on eaither band and the
the a3s works fine but my amp would like a little better SWR
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