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Re: N3IYR S-Band dishes



I had a quick look at the N3IYR web site last night. At
least one statement he makes is untrue, it makes you wonder
about the rest.

He states that you have to have a solid dish at 2.4 GHz, this
is rubbish. Go to any decent textbook about dish antennas and
you will find that you can use a mesh provided that the holes
in it do not exceed a certain fraction of a wavelength. Even
my 11 GHz satellite TV dish is perforated, albeit with very small
holes.

His feed does indeed look like a helix, and it may be the best
option anayway. The patch is a lovely antenna, I use the K3TZ
designed patch and I am very happy with it, but it only works
with dishes with a certain f/D ratio. In comparison the helix
is flexible as it can be adjusted to suit many different f/D
ratios depending on the number of turns. It so happens that with
the f/D ratios that are ideal for a patch, you need a very small
helix feed, and the helix is starting to get very inefficient. So
the patch wins easily.

Jonathan  G4KLX / HB9DRD
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