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RE: Circular patch behaves linear

>elliptical polarisation at 45 deg to the patch edges, which looks great on 
>a 0 and 90 deg sample but terrible when you sample at 45 deg 
>intervals!  To minimise the effects of moving cables etc getting in the 
>way, I used a rotating joint behind the test antenna.  Test equipment was 
>an ANA with the patch on port 1 and the sampling antenna on port 
>2.  Spacing between patch and sense antenna was in the order of 15 inches 
>giving a measured loss of about 30dB if I remember correctly.
>simulated (double dip with higher frequency dip deeper) with second dip

Hi Charles,

A lot of us have been reading your comments with a great deal of interest, 
keep them coming...

Some may be interested in the way I developed a patch feed several years ago.
My test equipment is minimal, no convenient way to determine circularity so 
I just use the sun, and tune for "max smoke"....  A dual feed "patch 
tester" is under construction!!

My original "patch tester" is at:


with the following files there:


The completed patch that I use now is PATCH2.ZIP

I use it on a 30" dish, and hear the noise floor very well...

            73, Dave wb6llo@amsat.org
                    Disagree: I learn.... 

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