[TowerTalk] Sufficient ground or counterpoise for VHF/UHF antenna?
Kevin Zembower
kevin at zembower.org
Fri Dec 24 13:39:31 EST 2021
Hello, all, and happy holidays to those that celebrate them!
Rumor has it that I can expect a new VHF/UHF radio under the tree
tomorrow. This will be my first VHF/UHF base station. In preparation, I
have an about 40 inch VHF/UHF whip antenna on a magnetic mount in my
attic, stuck to a 24 x 35 inch piece of heavy gauge galvanized sheet steel.
Is this adequate for a ground plane or counterpoise? I know it's not the
mass of a vehicle. The SWR is pretty good, I think. It goes from about
1.45:1 to 1.3:1 over the VHF band, and 2.5:1 to 1.3:1 in UHF (with a
consistent set of big fluctuations at 440 and 445MHz. What's that about?).
Would this system be improved by four wires run to the corners of my
attic and electrically bonded to the sheet steel? Would more wires be
better? There's no easy way to ground it to earth from up in the attic.
Thanks for any advice or guidance. Happy New Year to all!
-Kevin
KC3KZ
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