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Re: The best feed for my Dish?



On 8 Dec 2003 at 22:52, Luc Langehegermann wrote:

> Hello,
> 
> I have got relativly cheap an 1m mesh dish, approx. 125mm deep, so with an f/D 
> of 0.5. So, the feed should have an illumination angle of approx 105° (-10dB 
> Beamwidth)
> 
> The G3RUH Patch feed does have an illumination angle of 125°, the K3TZ one 
> around 120° (?) so they both will probably overilluminate the Dish.
> 
> So what feed should I use. An 3 turn helix seems to come close to the optimum, 
> but Patch feeds do have an better efficiency.
> 
> Any suggestions?
> 
> Thanks, Luc, LX2GT

Hi Luc

Here i choose the patch feed, but installing it closer to the dish to reduce overillumination. I will end up 
with less gain and less noise. I check here different position on my 2.2M dish with 2 different patchs feed 
and i cannot see greath difference for up to 15cm distance variation. (but i can see variation in noise and 
signal  level)



Luc Leblanc VE2DWE
Coordonnateur AMSAT pour le Québec
Quebec AMSAT coordinator
AMSAT MEMBER (33583)
Sites web sites: www.qsl.net/ve2dwe
                          www.sorel-tracy.qc.ca/~luclebla/

Echolink node 115340 VE2DWE-L
Echolink node 101810 VE2DWE

P.O. Box 341
Sorel-Tracy  QC.
Canada
J3P 5T6

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