"Richard Clark" wrote in message
...
On Tue, 6 Feb 2007 22:35:04 -0500, "Stefan Wolfe"
wrote:

2. The effect of the 80m hill 10Km away is negligible. The arc tan is only
.008 degrees, thus the transmitter hardly "sees" it.

Actually, Stefan, the transmitter cannot see through it at all.

Exactly . And taking into account the 15 degree bend of the radio horizon
(even at 10 GHz) vs the arctan of .008 degrees for the the hill, reduced
somewhat by the 20 foot transmitter tower to .006 degrees, the hill itself
is invisible at a 30km far field. The bend of the propagating waves which
extends the radio horizon clearly mitigates any possible effects of the 80m
hill.