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Re: SkyCross 2.4 ghz antenna?



Hi All,
I am not impressed, For satellite you want hemisphere performance with gain
a low angles. For a Dish Feed the gain of the feed is determined by the F/D
ratio, the gain is in the dish and you lose when you over or under
illuminate the dish. With AO-40 concrentating on making a good axial ratio
circular feed payed off in a steady signal. I found that this was best
achieved by making the plate slightly retangular and cliping two ends. This
yeilded less than 1 dB of change while rotating a linear antenna 360
degrees. The same test on a 4 turn helix yeilded 4 dB of diference.

Art, KC6UQH
----- Original Message -----
From: "Greg D." <ko6th_greg@hotmail.com>
To: <amsat-bb@AMSAT.ORG>
Sent: Friday, February 04, 2005 1:07 PM
Subject: RE: [amsat-bb] SkyCross 2.4 ghz antenna?


> I guess it would help to give you the URL...
>
> http://www.skycross.com/pdf/em2450ma.pdf
>
> Greg  KO6TH
>
>
> ----Original Message Follows----
> From: &quot;Greg D.&quot; &lt;ko6th_greg@hotmail.com&gt;
> To: amsat-bb@amsat.org
> Subject: [amsat-bb] SkyCross 2.4 ghz antenna?
> Date: Fri, 04 Feb 2005 09:35:28 -0800
>
> Hi folks,
>
> I ran across this on the Web...  It's hard to tell from the picture, but
it
> seems to be a different kind of antenna.  Not a patch, not a helix.  By
the
> specs, a pretty good emulation of an isotropic radiator (no gain, omni
> directional).
>
> Does anyone know how they work, or how they might perform over a ground
> plane as a feed for a dish?  They would seem to be very easy to make...
> 1&quot; square of tin and a pair of scissors.
>
> Greg  KO6TH
> ----
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> Sent via amsat-bb@amsat.org. Opinions expressed are those of the author.
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----
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