[TowerTalk] ANTENNA RESONANCE VS HEIGHT ABOVE GROUND - DATA POINTS?

[Larry - K7SV]

Hi all,

We're in the midst of building a fairly long boom yagi for 20M. When 
completed it's going to be at 190ft. We expect to initially tune it (T 
Match) at 15 ft and then tram it to 80 ft or so for further tuning before 
bringing it up to full height.

Initial thought is to tune it 200khz low at 15 ft, but that's just a guess. 
Are any of you aware of data available that might make this a little easier 
than simple trial and error. This will no doubt display a curve that sharply 
rises as one moves an antenna from ground level to some height above ground 
and from there on up to our working height the percentage of change becomes 
fairly small. I'd guess from 30 feet on up the rate of change would be 
greatly reduced from what one would see between ground level and that 
height.

As I think about the question, I find I'm asking myself if there is anything 
in modeling that might provide some answers, but if that were possible I'd 
expect that Steve NR4M who developed the design based on YO would not be 
looking for your help!

73 de Lar K7SV