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Re: Dish Question



on 5/9/03 9:53 PM, George Humphrey wrote:

> This is probably a really stupid question, but does dish size have any
> relationship to frequency, or is it just "bigger is better"?

George,

Ed had a great reply and I'd agree.

Bigger is better, but for working satellites you can get too big.  The
bigger the dish, the narrower the beamwidth.  This means your pointing
accuracy has to be better.  For AO-40, if you have a dish big enough to hear
the noise floor of the transponder, having an even bigger dish won't help
all that much except for marginal conditions (when the bird is at bad
squint, etc).  The typical size that is recommended for AO-40 is a 3 foot
dish for S-band.  However, there are people that successfully use smaller
dishes and bigger dishes.

Now, on AO-40 for K band, many people use an 18" dish.

As frequency goes up the gain for a given size of dish moves up as well.  So
size does relate to frequency and bigger is generally better.

73,

Jon
NA9D
-------------------------------------
Jon Ogden
NA9D (ex: KE9NA)

Citizen of the People's Democratic Republik of Illinois

Life Member: ARRL, NRA
Member:  AMSAT, DXCC

http://www.qsl.net/na9d   <- Updated on 1/22/03!!!

"A life lived in fear is a life half lived."


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