|September 30, 2002
This is a start to the project of putting some of my surplus big dishes (5' up to 10') on AO-40. These dishes are all prime focus, nominal 0.3 f/d dishes +/-.
First order of business, decent patch feeds. Ok, mounting the
dish should be first, but I have to actually get the new QTH built completely!
|Oh, well, back to feeds....
I've tried many designs, and it appears that the G3RUH-type feed is superior to others. Not that I don't believe that a square patch (rectangular) couldn't be made to work as well, I've just not found the magic combination.
As far as the actual G3RUH feed-- at $170 US I can't afford it.
Not wanting to re-invent to many wheels, I am relying on the research
of W0LMD who has made a simplified version of the type of patch design
I'm notorously bad at measuring round things, so I took a little time and came up with a CAD drawing that summarizes the dimensions from W0LMD's site.
So far I have a correctly scaled (at least on two different manufacturer's printers here) Adobe Acrobat file that contains a template for cutting and drilling the single-band (or dual-band portion of the) 2401 MHz circular patch that Dr. Suding mentions on his site.
W0LMD 2401 MHz Circular Polarized Patch Feed Template