[amsat-bb] Antenna Polarization Question

[jim at k6ccc.org]

When a CP signal, bounces off a reflector, it reverses polarity.  So if you are wanting to generate a RHCP pattern from a dish antenna, the feed needs to be LHCP so that it will come out RHCP after bouncing off the dish.  Make sense?
 
 
73
-----
Jim Walls - K6CCC
jim at k6ccc.org
 

-----Original Message-----
From: "Greg D" <ko6th.greg at gmail.com>
Sent: Wednesday, March 21, 2018 16:36
To: "Jean Marc Momple" <jean.marc.momple at gmail.com>, "Wendy and Terry Osborne" <wandtosborne at gmail.com>
Cc: amsat-bb at amsat.org, "Burns Fisher" <burns at fisher.cc>
Subject: Re: [amsat-bb] Antenna Polarization Question



Jean Marc Momple wrote:
> In a nutshell/ my conclusion/ advice on the RHCP/LHCP issue: to operate the birds for HAM purpose the simplest way is just to have polarization relays on both uplink and downlink antennas, then manually switch polarization as required depending on the fading, which has quite different patterns depending on the bird and their trajectory, after some time an practice it becomes natural and you push the button without even thinking. I do so all the time during Sat. passes.

I think this is the best advice... :)

Greg KO6TH

p.s. All this said in the thread, I am a still bit confused. I thought
circular polarization was like nuts & bolts. You can thread the nut on
a bolt with either piece in either direction; the thread on them doesn't
change just because you picked it up "backwards." I can see the
possibility of a reverse polarization in the side lobes, but out the
back of the antenna shouldn't it be the same as the main lobe? Or am I
nuts (pun intended)?
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