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Re: Wet Trees?



Art,

I agree that with so much variation, it would be difficult to gauge foliage 
attenuation or relate your backyard trees to some kind of standard. But to 
the best of my knowledge, attenuation is still proportional to frequency.

All things being equal, the higher the frequency, the greater the 
attenuation. I metioned the "textbook" 3db per meter of foliage for 2.4Ghz 
to give Emily some idea of what to expect from her situation. I guess you 
could extrapolate from there.

73, Tony KT2Q

> Tony,
> I think that determining the attenuation of foliage is folly. There are so
> many different types of leaves, different square areas, different moisture
> levels, and different densities that defy quanitization. I do ATV and
> general opinions of others on ATV is if there are trees you are dead duck 
> as
> far as sending and receiving signals above 2 M  Removing some bushes in my
> front yard rased the 10,368.330 beacon from an S1 to 10dB over S9
>
> Art,KC6UQH
> ----- Original Message -----
> From: "KT2Q" <dxdx@optonline.net>
> To: <amsat-bb@AMSAT.Org>
> Sent: Thursday, January 27, 2005 8:55 PM
> Subject: Re: [amsat-bb] Wet Trees?
>
>
>> Emily,
>>
>> I asked a similar question a while back about AO-40's S-mode downlink. 
>> The
>> answer I got was that most satellite communications text books state that
>> attenuation at 2.4Ghz was about 3db per meter of foliage. Assuming that
>> foliage attenuation varies with the square of the frequency, there should
> be
>> much less atennuation at 435mHz than 3db per meter.
>>
>> I'm sure Dominico ( I8CVS) would have the answer to this one.
>>
>> 73, Tony KT2Q
>>
>>
>>
>> > On Thu, 27 Jan 2005 08:01:51 -0800, Emily Clarke <w0eec@amsat.org>
> wrote:
>> >> In the past few months I've noticed that there are days when I just
> can't
>> >> work SO-50 below 12 degrees
>>
>> >> 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
>> ----
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----
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