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attenuation of various tree types



Jonathan Naylor wrote:

It all depends on the tree, Firs are instant death for signals. However
less dense trees are not so bad, and I am able to operate 10 GHz
through some local trees, I don't know the type but you can see through
them quite well and the signals do also.


Wayne replies:

Here's my empirical observation of the 2401 MHz attenuation of the trees
around me.

Silver Maple (a sparse tree with medium-size leaves, east of my antennas):
Attenuation in summer is about 2 S-units.  Attenuation in winter is barely
noticeable.  I think S-units on my FT-847 are about 3 dB.  So that would be
about 6 dB attenuation in summer.

Sugar Maple (a dense tree with large leaves, west of my antennas):  In
summer I can't hear the beacon through these trees, so the attenuation is
more than 4 S-units.  In winter the attenuation is about 1 S-unit if I'm
only looking through one tree.  At low elevations in winter I look through
multiple bare trees, and the attenuation is much greater.

Using a G3RUH dish, patch feed, and 0.7 dB NF downconverter, 2 S-units of
attenuation makes SSB contacts extremely difficult.  CW contacts are still
relatively easy, though.

Two common "see through" trees in the U.S. are Honey Locust (in the north)
and Mesquite (in the south).  I imagine they have very little attenuation at
2401 MHz.

Wayne Estes W9AE
Mundelein, IL, USA


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