[TowerTalk] Effect of Ground Quality and Terrain vs Distance from Antenna?

[Joe Giacobello]

I have read in several reliable sources that it's really the quality of 
the ground and the terrain about 2-1/2-3 wavelengths from the antenna 
that determines the effective height of an antenna and the resulting TOA 
and gain.  If that's the case, does that mean that a 40M antenna on a 
hill that rapidly drops off by about 400 feet in height over a radius of 
about 350 feet effectively increases the height of the antenna by 400 
feet?  I know some of you folks out there have done terrain analysis and 
wonder if that conclusion is accurate?  Again, if that's accurate, does 
it make more sense to put the radials for a ground mounted vertical 
2-1/2 to 3 wavelengths from the antenna rather than directly under it?

I'd be interested in your comments on these questions.

73, Joe