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

[Jim Brown]

On 12/24/2021 10:39 AM, Kevin Zembower via TowerTalk wrote:
> Is this adequate for a ground plane or counterpoise? 

Yes
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?).

Either resonances in the sheet steel based on its dimensions, or 
conductive surrounding objects. SWR is NOT a measure of antenna 
performance, it only increases loss, and for the values you've measured, 
not by much. If the feedline isn't very long, I wouldn't worry about it. 
But I WOULD use coax bigger than RG58, which gets pretty lossy at VHF, 
even more at UHF. RG8X is a good choice.

73, Jim K9YC