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13cm feed question.



Hi AMSATs,

Like my many attempts before, the last attempt to hear AO40 again failed :-( 
After doing many tests and changes, I think I must conclude that the problem 
has to be in the antenna.

The antenna I use in an metal can with an 1/4 lambda element as an feed in 
front of an 60cm dish. I tested the feed at my spectrum analyser with an 
sweep generator, and I tuned it to minimum SWR.

So I would say it is okee, but now I have some other idea what might be the 
problem. Maybe the length of this can is to long, and the RF energy is not 
covering the complete dish. When it will be only covering a little part in 
the middle of the dish, the feed will recieve only little RF. Because the 
feed is in the middle of the dish (no ofset dish) it also blocks more of the 
RF energy.

Somebody has any idea if this might be the problem ?

I am thinking to make some 13cm loop yagi and try if this will work. Maybe 
somebody has experience with recieving AO40 with loop yagi ?
When loop yagi's work, they can be interresting as addition to my portable 
back-pack equipment for AO40 :-) Better than heavy dish :-)

73 de PE1RAH, William
pe1rah@hotmail.com



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