[amsat-bb] Re: Antenna Polarization Technical Question
domenico.i8cvs at tin.it
Sat Aug 4 20:06:59 PDT 2012
Hi Tom, KN6ZA
With only a 3db loss you can use a linear rec. antenna with no polarity
switching, and avoid the large fading that would occur if the satellite was
transmitting circular RHCP or LHCP........(but not linear as you stated)
On the other side if you receive linear and the satellite transmit linearly
with opposite polarity you get more than 20dB of fading.
----- Original Message -----
From: "andrew abken" <kn6za at hotmail.com>
To: <tomdoyle1948 at gmail.com>; <amsat-bb at amsat.org>
Sent: Saturday, August 04, 2012 10:45 PM
Subject: [amsat-bb] Re: Antenna Polarization Technical Question
> I don't think any one who designs a system "wants" this to occur, but
as a function of overall system cost it is one of the unavoidable realities.
> Its actually a great compromise, because with only a 3db loss you can
use a linear rec. antenna with no polarity switching, and avoid the large
fading that would occur if the satellite was transmitting linear.
> Now if you have the money to build a satellite that can point itself at
the receiving station at all times ie: geo synchronous:)$$$$ then that would
be the cats meow;)
> > Not sure why anyone would want to maintain the orientation of the
> > satellite in such a way that would cause the direction of circular
> > polarization to change during the path. Perhaps people selling antenna
> > circularity switches would like it but other than that I do not
> > understand why it would be done. I am most likely missing something
> > important.
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