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RE: Echo Antenna Polarity



Art,

No, the only reason for the opposing polarities is to isolate the
transmitters from each other.  There will be no problem on the ground if you
choose to use linear polarization.

Rick
W2GPS
AMSAT LM 2232


-----Original Message-----
From: owner-AMSAT-BB@AMSAT.Org [mailto:owner-AMSAT-BB@AMSAT.Org] On Behalf
Of KC6UQH
Sent: Tuesday, July 06, 2004 12:31 AM
To: Rick Hambly (W2GPS); 'Bill Ress'
Cc: amsat-bb@AMSAT.Org
Subject: Re: [amsat-bb] 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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