[amsat-bb] Re: patch feed and proper dish

[Ronald Long <rlong3@xxxxxxxxxxxxxxx>]

I would like to add one more comment to my previous post on this topic.

Some 'modern' solid dishes have a rounded outer edge. This is not just to 
make them look pretty or for some structural reason. A properly designed 
rounded edge cuts down on edge diffraction with consequent reduction in 
back lobes in the final pattern. What is properly designed? If there is 
interest I'll dig out a reference. As I recall it has to do with frequency 
and radius of the 'roll'. By the way the 62cm solid dish I mentioned does 
have a rolled edge although I have not pursued its dimensions vs. 2.4GHz. 
This dish is a one of a kind that I bought several years ago at one of the 
AMSAT-NA symposiums. It seems to be military in that it is painted olive drab.

ron w8gus.

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