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Re: XM Radio Antennas as Patch Feeds??



At 11:02 PM 2/7/2003 -0600, Jon Ogden wrote:
>Hey guys,
>
>I was thinking about an economical way to get a decent preamp and patch feed
>if the time ever comes when I go to a bigger dish.  Since I have XM Radio, I
>got to thinking about some stuff.
>
>XM operates at 2332.5 to 2345 MHz.  The LNA on the antennas has a 0.8 dB NF
>with about 20 to 24 dB gain.  The satellite portion of the antenna (it has
>capabilites for receiving terrestrial repeater signals) is circularly
>polarized.

Most likely right-hand CP which makes it opposite what you want for an
AO-40 feed (LHCP feed --> RHCP after reflection from the dish).

>The best thing is that these things cost about $50 and are in a waterproof
>housing.
>
>The question is what sort of bandwidth they have.  The Terk web page says
>that the bandwidth is 12.5 MHz.  But that's what XM's bandwidth is.  I
>wonder what the real capabilities are.  There may be some internal filtering
>that will really limit it.  The polarization of the internal patch may be
>wrong.  I don't know.

Most likely is does not have a narrow filter which means the gain-bw may be
5% of Fo (120 MHz).

>Has anyone messed around with one of these and characterized it up to 2401?
>It could be close but no cigar, or it could be an economical feed antenna.
>I'm curious.

Is it powered via the coax and what voltage?  Why not try it?

Ed - AL7EB
>
>73,
>
>Jon
>NA9D
>-------------------------------------
>Jon Ogden
>NA9D (ex: KE9NA)
>
>Citizen of the People's Democratic Republik of Illinois
>
>Life Member: ARRL, NRA
>Member:  AMSAT, DXCC
>
>http://www.qsl.net/na9d   <- Updated on 1/22/03!!!
>
>"A life lived in fear is a life half lived."
>
>
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