Jeff wrote:

If you understand what I wrote above, you'll see my point was about
local conductivity and how it affects the radiation pattern after being
launched from an antenna, rather than the variability along a signal
path, although I did mention for completeness that models can now take
such variability into account.


Spike

I think it is your choice of words that is causing the confusion. It is
not normally the practice to consider the ground conductivity over the
entire transmission path when considering the radiation pattern of an
antenna. It is usual to have a 'local' radiation pattern and then
consider what happens on the path as a separate (path loss) issue.

Ground conductivity more that a few wavelengths from the antenna has an
insignificant effect on the antenna pattern.

Ground conductivity around the antenna has a small effect on the antenna
pattern in the real world.

If you doubt this, download the free demo version of EZNEC and compare
the pattern of an antenna over average ground to an antenna over
poor ground.


--
Jim Pennino