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Re: Wet Trees?



Re Wet Trees,
We ( PARC) have noticed and are careful to locate all antennas for 70 cm and
higher frequencies above the tree line on Palomar Mountain. 6 M and 2 M do
not seem to be affected, but the difference on 70 cm is very noticeable.
Another effect is when the temperature inversion layer is well formed making
it impossible to bring up our repeaters from some locations. Our repeater
site is at 5600 feet and about 30 miles from the coast. During the summer
the output from our repeaters on 2 M measured from a site that has line of
site, can vary as much as 10 dB during the day.

Art, KC6UQH
----- Original Message -----
From: "Emily Clarke" <w0eec@amsat.org>
To: "AMSAT BBS" <amsat-bb@amsat.org>
Sent: Thursday, January 27, 2005 8:01 AM
Subject: [amsat-bb] Wet Trees?


> In the past few months I've noticed that there are days when I just can't
> work SO-50 below 12 degrees (normally getting down to 5 to 6 depending on
> the azimuth.) The signal seems to fade in and out as the satellite moves
in
> azimuth, sometimes becoming stronger at a lower elevation.  It usually
> seems to happen after there has been a rain.
>
> After testing power out/VSWR and passing the test, the next thing that
came
> to mind is that the wet trees, mostly thick pines and laurels which still
> have their leaves, are attenuating the signal more than when they are
> dry.  Does that seem possible?
>
> 73,
>
> Emily
>
>
>
> ---------------------------------
> W0EEC - CM87tm
> AMSAT Area Coordinator - San Francisco Bay Area
> http://www.projectoscar.net    http://www.PlanetEmily.com
>
> Join AMSAT!  http://www.amsat.org
> ----
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