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Topband: Trees As RF Absorbers & Antennas

To: "a COL Topband E-List" <topband@contesting.com>
Subject: Topband: Trees As RF Absorbers & Antennas
From: "Thomas Giella KN4LF" <kn4lf@tampabay.rr.com>
Date: Mon, 13 Oct 2003 10:14:26 -0400
List-post: <mailto:topband@contesting.com>
  The possible negative absorptive effects of locating an antenna transmitting 
setup for 160 meters in a dense forest would be very difficult to measure. If 
the antenna feedpoint impedance changes when the leaves of the surrounding 
deciduous trees fall off in the Fall season and then again in the Spring season 
when the leaves grow back, you could presume that some sort of interaction was 
occurring. But at a wavelength of 160 meters I think losses would be 
insignificant. 
  If you set up two identical 160 meter transmitting 1/4 wave vertical antennas 
one mile apart, one in dense forest and the second one in an open pasture, as a 
receiving station I think you would be hard pressed to be able to tell the two 
apart as far as signal strength, taking into account normal QSB.
  As far as actually successfully using trees for transmitting antennas, I 
think that KF4BWG is being fooled because his BALUN less feedline is doing the 
radiating.

73,
Thomas F. Giella, KN4LF
Plant City, FL, USA 
EL87WX

KN4LF 160 Meter Amateur Radio Resources & More:
http://www.kn4lf.com/kn4lf.htm

KN4LF Daily Solar Space Weather & Geomagnetic Data Archive:
http://www.kn4lf.com/kn4lf5.htm
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