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Re: Using C band polar mounts w/ ao-40



>From: KB7WW Art Moe <kb7ww@chatusa.com>
>Maybe my theory and thinking is wrong, but lets say that a dish has 
>a surface error of .5 wave length at 4 Ghz then it would only have an
>error of .25 at 2 Ghz making it BETTER. Or am I thinking wrong. 
>Although at 2 Ghz it still has less gain than at 4 Ghz. 

Tony, Art:

Any roughness in the dish surface becomes less important as frequency
drops.  Many newer c-band TVRO dishes are rated for ku-band as well, so
depending on the individual dish mfr and model [and age], I think there is
little concern for use at either 1.2 or 2.4G.  As far as gain, a 3m
[ten-foot] dish will provide 12 dB more gain than a 2-foot dish, 10 dB more
than a bbq grill dish, and much-much more than most helical beams.  At 2400
a ten-foot dish will show 36 dBi and a bw of 3 degrees; at 1269 gain is 30
dBi, bw 6 degrees.

If I had an equatorial mount TVRO dish I would definitely try it [I have a
33 inch ku-band fixed dish, and a 2.5m az-el dish with drive not in service].

Ed 


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