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[TowerTalk] trees and verticals

To: "" <>
Subject: [TowerTalk] trees and verticals
From: Roger Parsons <>
Reply-to: Roger Parsons <>
Date: Wed, 28 Dec 2011 14:10:53 -0800 (PST)
List-post: <">>
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

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