# Re: Circular Polarization

• Subject: Re: [amsat-bb] Circular Polarization
• From: "Bobbie Johnson" <bobbiej@xxxxxxxx>
• Date: Sun, 25 Oct 1998 21:14:34 -0500

```Agreed. Visuallize yourself standing behind the antenna. Determine if it is
RHCP or LHCP and back up until you reach earth. Nothing changes..

Bobbie  KD4LV
-----Original Message-----
From: Dave Cawley <Timestep@dial.pipex.com>
To: amsat-bb@AMSAT.Org <amsat-bb@AMSAT.Org>
Date: Sunday, October 25, 1998 7:13 AM
Subject: [amsat-bb] Circular Polarization

>From: Dave Cawley
>Cambridge  England
>Timestep@dial.pipex.com
>Tel.  +44 1440 820040
>Fax. +44 1440 820281
>
>
>Dear all
>
>
>My original comment was that I did not understand a comment about a
>satellite's orientation.  I now understand that a satellite due to poor
>stabilization, can turn up-side-down, and have it's antennas pointing out
>into space.  It was further suggested that when the antennas were pointing
>into space, that the received signal would be of the opposite polarity than
>normal, that is to say, pointing towards Earth RHCP and pointing to the
>stars LHCP.
>
>Various analogies were used and exchanged, and the flaws of using analogies
>were exposed !
>
>The difficult point to visualize, is the signal radiation out of the back
>of an antenna, so just suppose for one moment you take a 8 turn helical
>antenna, and remove the reflector.  Then instead of feeding it at the end,
>feed it half way up, this is easier to visualize.  Now look into  what
>would be the front and observe the polarity, then look into the back where
>the reflector once was and observe the polarity.  The one in my garden;
>the polarity is the same.  Proving, in this illustration, that polarity is
>truly intrinsic once the antenna has been made, and that the signal
>received from a satellite with it's antennas pointing skyward is still RCHP
>
>Now, the good news is, that I'm nearly off to visit the Fort Lauderdale
>Super Yacht Show, where amongst other things I will be exhibiting the
>Worlds most expensive Quadafilar Helix Antenna.  So you can come and visit
>me, and ponder on circularity, with a Bud or two ?  And those on the list
>will find a sudden stop to this thread on Tuesday night ?
>
>
>Regards
>
>Dave G4IUG
>----
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>

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