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RE: Echo Antenna Polarity



Art,

No, there is one transmit antenna consisting of a phased array of four
monopoles that is fed by the hybrid combiner to produce circular
polarization.  There are two inputs to the hybrid combiner that are
internally mixed in such a way that one of the inputs will result in the
antenna producing RHCP, the other produces LHCP.

Both transmitters operate simultaneously on slightly different frequencies
and both use the same antenna but the results are different.

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 11:56 AM
To: Rick Hambly (W2GPS); 'Bill Ress'
Cc: amsat-bb@AMSAT.Org
Subject: Re: [amsat-bb] Echo Antenna Polarity

Rick,
You mentioned two transmitting antennas of left and right hand rotation for
isolating two transmitters. Are these transmitters intended to be operated
on the same frequency, at the same time? If so linear polorization will not
sepreate them.

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.
> Not an AMSAT member? Join now to support the amateur satellite program!
> To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org


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