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From: Bob Bruninga bruni...@usna.edu
To: Thomas Doyle tomdoyle1...@gmail.com
Cc: amsat-bb@amsat.org; andrew abken kn...@hotmail.com
Sent: Sunday, August 05, 2012 12:24 AM
Subject: [amsat-bb] Re: Antenna Polarization Technical Question
Not sure why anyone would want to maintain
is very desirable.
Art,
KC6UQH
-Original Message-
From: amsat-bb-boun...@amsat.org [mailto:amsat-bb-boun...@amsat.org] On
Behalf Of Bob Bruninga
Sent: Saturday, August 04, 2012 3:25 PM
To: Thomas Doyle
Cc: amsat-bb@amsat.org; andrew abken
Subject: [amsat-bb] Re: Antenna Polarization
@amsat.org; 'andrew abken' kn...@hotmail.com
Sent: Sunday, August 05, 2012 10:44 PM
Subject: [amsat-bb] Re: Antenna Polarization Technical Question
Bob,
Just a reminder, a QFH antenna is circularly polarized over the whole
envelope of the antenna. A sharp null exists on the back side. A one
Message-
From: i8cvs [mailto:domenico.i8...@tin.it]
Sent: Sunday, August 05, 2012 3:27 PM
To: AMSAT-BB; Bob Bruninga ; kc6...@cox.net; Thomas Doyle
Subject: Re: [amsat-bb] Re: Antenna Polarization Technical Question
Hi Art, KC6UQH
It is correct that a QFH is circularly polarized over the whole
Andy,
I believe that is true but that does not explain why the optimum
polarity setting on the receive end would
change during a pass. Perhaps there is some sort of Faraday Rotation
effect but I do not believe that
it can change the direction of the circular polarized signal but who
knows what
Hi Tom,
I have also noticed the switching of polarity as the sat travels over.
What I have understood to be the mode by which this is occuring comes from
the fact that circular polarized antennas change polarity as you move out of
the main radiation lobe. The main lobe is circular
I believe that is true but that does not explain
why the optimum polarity setting on the receive
end would change during a pass.
That's easy. The circularity on a pair of crossed dipoles (about all you can
get on a spacecraft) May be designed for Right hand circularity when viewed
from
Bob,
Thanks for the reply. A student of mine once told me that if someone
tells you something is easy - it is not. Even though this is not only
easy but very easy I still need a slight clarification. I think it
boils down to the orientation of the satellite relative to the center
of the earth.
I can't explain it but have noticed the same polarity changes during a
pass. Like S-9 to S-1/nothing switching between polarities with my
antennas... it's been handy to actually have the ability to change
polarities in the past for me. I do not have the ability to polarity
switch on 2 meters,
Tom,
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
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.
There are two perspectives in answering this.
1. You used the word maintain, which implies the ability of the
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.
Lets try this approach... As I said before, By the laws of physics, what comes
out one side of a circular polarized
Hi Thomas, W9KE
In a separate email I have sent to you a very compreensive article
explaining why during an orbit of a LEO satellite like FO-29 the
changes in polarization is generated.
73 de
i8CVS Domenico
- Original Message -
From: Thomas Doyle tomdoyle1...@gmail.com
To:
transmit linearly
with opposite polarity you get more than 20dB of fading.
73 de
i8CVS Domenico
- Original Message -
From: andrew abken kn...@hotmail.com
To: tomdoyle1...@gmail.com; amsat-bb@amsat.org
Sent: Saturday, August 04, 2012 10:45 PM
Subject: [amsat-bb] Re: Antenna Polarization
...@gmail.com
Cc: amsat-bb@amsat.org; andrew abken kn...@hotmail.com
Sent: Sunday, August 05, 2012 12:24 AM
Subject: [amsat-bb] Re: Antenna Polarization Technical Question
Not sure why anyone would want to maintain the
orientation of the satellite in such a way that
would cause the direction
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