I think the general rule of thumb I see mentioned is to use a dish
with a diameter at least 10X the wavelength being used. However, I
have been using a 2-foot diameter dish on 2304 and up and it works
quite well. My best DX with it has been about 500 miles on 2304
through 10368 MHz running two watts.
Using a 5 foot dish on 432 might be a little too small of a dish, but
I suspect it would work on 1296.
The other consideration is if a dish is too big, the beam width gets
so narrow that it's difficult to find the other station and keep the
dish aligned on it (especially in a strong wind). I've seen people use
a 2 foot dish on 24 GHz but it's really tricky to use on that band. A
1 foot dish has a wider beamwidth but not as much gain. So it's a
trade-off.
73, Zack W9SZ
On Thu, Jan 28, 2010 at 11:18 PM, David Ashworth <ahab@sonic.net> wrote:
> Hello to the group, hope everyone is well. I have a question as regards
> microwave reflectors. A fellow ham buddy has two military surplus microwave
> reflector dishes 4 or 5' around, could measure them if that helps. They
> have a hole in the center and some holes around the center hole that
> probably mounted the guts of the antenna. So, my question-is there a good
> rule of thumb as to what frequencies will work with a certain size of dish?
> For example, with a 5' dish, could I put in a dipole element similar to what
> a corner reflector uses, say for 432? Or, would these be for something
> higher in frequency? Haven't had much experience with these, so any help or
> pointers will be appreciated. Thanks in advance, happy trails, Dave, NC6P
>
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