Re: [amsat-bb] Patch (K3TZ) Questions

["Bill Acito" <w1pa@xxxxxxxxxxx>]

Could something like this be used as a dish feed for the downlink ($40 on
special)?

http://www.hyperlinktech.com/web/hg2408p.html
(I have no financial interest in this company)

Bill
W1PA


----- Original Message -----
From: "Frederick M. Spinner" <fspinner@hotmail.com>
To: <w1pa@hotmail.com>; <amsat-bb@amsat.org>
Sent: Tuesday, July 02, 2002 12:59 PM
Subject: Re: [amsat-bb] Patch (K3TZ) Questions


>
> Since the patch is at zero ohms in it's geometric center anyway, just
screw a stud to the ground plane there.  This will not work on a "slotted
antenna", however.
>
> The impedance of a patch varies from about (depending on design) from 200
Ohms on the periphery to zero ohms in the center.  The 50 ohm point is
somewhere about halfway between and this is why the feeds are in a little
from the edges.
>
> Fred W0FMS
>
> >From: "Bill Acito" <w1pa@hotmail.com>
> >To: <amsat-bb@AMSAT.Org>
> >Subject: [amsat-bb] Patch (K3TZ) Questions
> >Date: Mon, 1 Jul 2002 15:16:37 -0400
> >
> >1) Has anyone tried leaving the corners and putting a slot in the K3TZ
patch
> >design to ensure circular polarization? There seemed to be some
discussion
> >(from K3TZ himself, no less) that the design is not c-polarized
(although,
> >from what I've read, folks are getting good performance anyway). Has
anyone
> >tried this design:
> >
> >http://nr.stic.gov.tw/ejournal/ProceedingA/v24n2/130-133.pdf
> >
> >...to see if this improves performance? I assume the scaled up dimensions
> >are way off because of the difference in dielectric constants between the
pc
> >board material in the paper and air. I even found references that K3TZ's
> >design _should_ be circular polarized:
> >
> >http://www.eetasia.com/ARTICLES/2001JUN/2001JUN15_RFD_AN.PDF
> >
> >but I am no patch design expert by any stretch of the imagination.
> >
> >2. G3RUH's patch is a grounded design (per his literature), to prevent
> >static damage to the front end. Again, I'm no expert, but is there any
> >reason why a 100K-1Mohm 1/8w resister couldn't be used as a standoff for
the
> >K3TZ design patch, providing a discharge path from the patch element?
> >
> >      ---|-------------------------
> >         R                    #
> >--------|--------------------#----------
> >
> >Bill
> >W1PA
> >
> >----
> >Via the amsat-bb mailing list at AMSAT.ORG courtesy of AMSAT-NA.
> >To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org
>
>
>
>

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