Topband: Trees As RF Absorbers & Antennas

Thomas Giella KN4LF kn4lf at
Mon Oct 13 11:14:26 EDT 2003

  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.

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

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