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RE: Patch Antennas




>
>The thing that probably saves the patch fed offset fed dish crowd is one 
>of the reasons that offset fed dishes exist at all. (They give better G/T 
>for space comms than prime focus dishes assuming a proper feed.)  Because 
>of the 20 plus degree "slant" of where the parabola slice points, the 
>overspill points up and not at the ground (Yah, they could still point at 
>a tree or building though), and the sidelobes point up into space somewhat 
>and not along the horizon.  So even though overillumination and sidelobes 
>hurt, they don't hurt as much as they do on a prime focus dish.
Hi Fred,

I compared a patch feed with an optimized helix on an offset dish, and it 
works just
as well as the helix.   I am in the process of optimizing the patch on the 
offset..
My offset is "upside down"....

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