[amsat-bb] Re: 10' Dish available

w7lrd@comcast.net w7lrd at comcast.net
Tue Oct 17 05:14:38 PDT 2006

Perhaps my helix feeds would be applicable.  Usually designed for off center dishes.  With fewer turns you would have a wider pattern. 
73 Bob W7LRD
-------------- Original message -------------- 
From: "Robert Bruninga" <bruninga at usna.edu> 

> > How does one build a feed to properly illuminate a pizza 
> slice-shaped 
> > reflector? Or is this a matter of 1/4 of a 10' dish being 
> still so 
> > over-kill that you only use the fat end, and under-illuminate 
> that? 
> Well, presumably one will be using this on S-Band either for 
> 802.11 or other 2400 MHz purpose so one has to build his own 
> feed anyway. Probably a dipole over a splashplate. That is 
> typically a good feed for a typical .4 F/D dish? If that is so, 
> then when it is used to illuminate just 1/4th of the dish area, 
> then there is spillover and a few dB are lost. Maybe a good 
> feed for the 1/4 quadrant dish might be a dipole over a 
> splashplate with a director? 
> Someone who is good on feeds might suggest the right answer 
> here... But in any case, one is not trying to illuminate the 
> tastey end tip of the pizza slice, but generally the center of 
> the crusty end... 
> De WB4APR, Bob 
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