On 1/22/2022 3:58 AM, John Langdon wrote:
The other thing that K5IU was clear about is that the ground under the
antenna is the dominant factor in performance regardless of the radials you
use.
Ground conductivity affects vertically polarized propagation in two
ways. First, loss very close to the antenna. THAT loss is minimized by a
good radial system. Second is loss in the Far Field where the first
reflection from the antenna is formed to create the vertical pattern.
Sea water is the extreme example -- we make the best possible contact
with it at the feedpoint to provide a really efficient counterpoise,
minimizing loss very close to the antenna, and its very high
conductivity results in a very strong reflection. The vertical pattern
is very narrow (low) if the antenna is very close to the surface. If the
antenna is raised, the vertical pattern remains strong, but gets very
"lobey." There are a few plots showing this in
http://k9yc.com/VerticalHeight.pdf
73, Jim K9YC
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