[TowerTalk] Sufficient ground or counterpoise for VHF/UHF antenna?

[Kevin Zembower]

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