[TowerTalk] trees and verticals

[Roger Parsons]

There has been a great deal of going around the houses.

The original question (and the one that I believe I answered) was related to the effect of trees. 


Wood is a poor conductor. Even wet wood is a poor conductor. Even tree trunks with sap 

rising are poor conductors.

Poor conductors in the vicinity of an antenna have very little effect on its radiation efficiency,
and are likely to have a very minor effect on the pattern. So it's usually fine to have an antenna
close to a tree. 


Lots of any lossy material surrounding an antenna (at any distance) will attenuate the signal
from that antenna. So it's not fine to have almost any antenna in a dense jungle, and it's not 

fine to have a UHF antenna firing through foliage. And so on and so forth....

See my original post which I think explained it better.

One final thought: 


It has been proposed on a number of instances in the past that the back-to-front ratio of a
Yagi could be improved by placing an 'absorber' element instead of, or as well as, the 

reflector. (That is an element deliberately made less conductive by, for instance, having 

a resistor at its centre.) It doesn't work, and it's quite easy to prove that it can't work.

73 Roger
VE3ZI