RE: [amsat-bb] Foliage Attenuation at 2400mhz?

["Robert Maxfield" <maxfield@xxxxxxxxxx>]

I don't have an AO-40 setup, yet, but have been working the FM birds as time
allows. (Soon though)  I have evergreen trees from 80 to 120 degrees azimuth
and I have never been able to get through them, the trees that is.  I
suppose I could stand on the house but then I still the bird would have to
be a minimum of 8 degrees in elevation to get a signal over the top.  (I'm
sure the neighbors get a laugh from watching me wandering around the
neighborhood with a hand held antenna, just to avoid tree antenuation.) You
are LUCKY to have deciduous trees.  I have been thinking about buying the
lot next door and logging it to pay for the AO-40 L band link.  You should
have heard the howl from my wife...........

-----Original Message-----
From: owner-AMSAT-BB@AMSAT.Org [mailto:owner-AMSAT-BB@AMSAT.Org]On
Behalf Of hasan schiers
Sent: Monday, July 29, 2002 4:58 PM
To: w2drz; amsat-bb
Subject: Re: [amsat-bb] Foliage Attenuation at 2400mhz?


Leaves are the biggest problems. I lose about 40 to 50 degrees of azimuth on
2.4 gig rx with AO-40 when the leaves come out. There are a ton of trees
around me and they are mostly deciduous (sp?)...i.e., leafy. When they lose
their leaves I get much better rx azimuth coverage. So, I find the leaves
much more problematic than the branches. 73

hasan schiers, N0AN

schiers@netins.net
or use amsat.org or arrl.net remailer
----- Original Message -----
From: "w2drz" <w2drz@madbbs.com>
To: "amsat-bb" <amsat-bb@AMSAT.Org>
Sent: Monday, July 29, 2002 12:52 PM
Subject: [amsat-bb] Foliage Attenuation at 2400mhz?


>
> Has anyone noted a difference when beaming through trees, with and
> without
> leaves? I'm sure moisture content in the leaf itself, and the leaf
> density
> the signal has to beam through plays any important part in how much
> attenuation takes place, but is there a general "rule of thumb"
> expressed in
> db for this band?
>
> Thanks
>
> Tony - AA2AE
>
>
>
>
>
> part of the answer as follows :
>
> tree noise / earth noise =
>
> the noise generated will increase the receiver background noise from 0
> db
> ( for a very poor receiver system, most likely not hearing sat)
>  to 6 db ( hearing sat fair to good )
>
> up to as high as 12 db + of noise using a hot rx system and pre amp , RX
> NF is .1 to .5 db noise figure, feed is a efficient feed and very good
> good antenna being used  is 20 to 30+ db of antenna gain , able to
> have/hear sat base band noise up to several db over back ground ,
>
> ( system is working excellent )
>
>  can check it by sweeping across the sat and observe the noise increase
> when pointed at sat .......
>
> attenuation will vary as to density of foliage can be a few db to total
> loss of signal 30+ db .... BUT the microwave noise generated by earth
> and/or  foliage is a major contributing loss of usable signal in
> addition to the attenuation of the foliage ..
>
> so answer is your system will work poorly or not at all pointing into
> foliage  ..
>
> am still playing with a 16f877 new controller design that uses dip
> switch settings for the use of pots ( 10 bit analog ),
>  incremental encoders, 16 bit parallel in, and absoult encodes ..
>
> will be back on sat shortly to join the fun when project is compleated .
> --
>
>
> best 73 tom W2DRZ  FN02LA       what we do:
> work: http://www.ramcoinc.com/index.php
> fun: Wild Women/fast cars*motorcycles/booze
> *** oops that was many yrs ago!!
> now just ham radio and chores for XYL
> Lat 42.02.27n Long 079.04.01w
> 12 digit grid FN02LA19XT22 EME on 1296 / 23 cm
> 6M WAS #505, VUCC 6M #857,2M #166,220 #21,432 #86,902 #29,1296
>  #38,2.3 #60,10 GHz #105
>
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