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post #19 of (permalink) Old 2011-10-19, 11:14 AM
Join Date: Jul 2009
Location: Eastern Ontario (Ottawa/Kingston)
Posts: 1,996

Yes, I believe it is quite possible to make a home made dish.

Another member (cyberham, post #7) mentioned a home made design seen in an ARRL magazine. American Radio Relay League (?)

I too have seen a home made design in a very old ARRL book. - when I was browsing in a library.

It was, I think, 12 ft dish made of 6 ft aluminum tension tubes as the frame, and mesh.
( the theory behind the design is that rods bent and held under tension form a parabolic shape ? I think that was the idea. )

The guy was using it, I think, for personal, home, Radio Astronomy hobby (!)

Yes, I've browsed (just a little) some of the calculations and theory behind satelite dish design - and it's very interesting.

You mention, you've got a 4ft dish but wanna have one a little larger? 5ft ?
I think that one (1) extra foot makes a big difference in receive area of the dish - and therefore a big difference in the receive capability of the dish.

Idea for all: What about extending an existing dish by adding an extra foot (ex. of mesh) around the outside? Possible? But that might alter the design characteristics of the existing dish some ... for sure.

Also, I have read that the higher in frequency you go, the more accurate the parabolic shape of the dish reflector has to be, and the more smooth the surface has to be.

(i.e. for C-band frequencies, the tolerances required are "do-able" by hobbyists, but if you go up in frequency, the tolerances get smaller and much harder for hobbyists to build realisticly. But higher frequencies usually require smaller dishes anyway - as the gain of the dish based on size also increases quite a bit as frequency increases - there's a formula I have seen that shows gain vs. size based on frequency)

Very interesting stuff. I am no expert - but the theory is fascinating.
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