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Re: Echo Antenna Polarity



Rick,
I guess the only question left, are the transmit frequencies close enough to
cause interference to each other if a linear antenna is used for receive on
the ground station? I would think the effort going to opposing rotations was
done for more than transmitter isolation.

Art, KC6UQH

----- Original Message -----
From: "Rick Hambly (W2GPS)" <w2gps@cnssys.com>
To: "'KC6UQH'" <kc6uqh@cox.net>; "'Bill Ress'" <diskdrives@ieee.org>
Cc: <amsat-bb@AMSAT.Org>
Sent: Monday, July 05, 2004 5:55 AM
Subject: RE: [amsat-bb] Echo Antenna Polarity


> Art,
>
> Back in the Nov/Dec 2002 AMSAT Journal I wrote: "AO-E has a UHF Turnstile
> Antenna that is fed by a strip line hybrid antenna phasing network that
> provides the appropriate quadrature phase and amplitude to each of four
> output antenna ports to produce true circular polarization over a wide
range
> of squint angles." For the full article see
> http://www.amsat.org/amsat/sats/echo/article-02-11.html.
>
> The turnstile antenna and the hybrid combiner have been redesigned since
> then.  It would be interesting to see if this is still true with some
tests
> after the satellite stabilizes a bit.
>
> Rick
> W2GPS
> AMSAT LM 2232
>
> -----Original Message-----
> From: owner-AMSAT-BB@AMSAT.Org [mailto:owner-AMSAT-BB@AMSAT.Org] On Behalf
> Of KC6UQH
> Sent: Monday, July 05, 2004 1:10 AM
> To: Rick Hambly (W2GPS); 'Bill Ress'
> Cc: amsat-bb@AMSAT.Org
> Subject: Re: [amsat-bb] Echo Antenna Polarity
>
> Rick,
> In the past with LEO's, the antenna pointing angle could sometimes
require
> both polarity's. This could happen every orbit or may remain stable for
> months dependent on the pointing angle of the antennas on the spacecraft.
>  As Echo has both polarities for isolation, am I correct in assuming that
> both polarities are necessary, will change with pointing angle, and linear
> antennas will not work if both transmitters are operating at the same
time?
>
> Art, KC6UQH
> ----- Original Message -----
> From: "Rick Hambly (W2GPS)" <w2gps@cnssys.com>
> To: "'Bill Ress'" <diskdrives@ieee.org>
> Cc: <amsat-bb@AMSAT.Org>
> Sent: Sunday, July 04, 2004 2:32 PM
> Subject: RE: [amsat-bb] Echo Antenna Polarity
>
>
> > Bill,
> >
> >-------------CUT-------------
>
>
> ----
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>
>
> ----
> Sent via amsat-bb@amsat.org. Opinions expressed are those of the author.
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