[TowerTalk] Vertical and radials

[Jim Brown]

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