[amsat-bb] DK7ZB 435MHz aerial question

Phil phillor at telstra.com
Thu Jan 28 22:53:18 PST 2010

Thank you for reading this.

I'm in the process of setting up my satellite station after a five year break 
and my UHF aerial doesn't seem to be performing as well as I expect it 
should. I always suspected that it's performance was below par. AO-51, for 
instance, is received no better than strength 3 on my FT-847.

The aerial is a twelve element design (twelve elements in each plane) by 
DK7ZB and is without a doubt the best 435MHz aerial that I have ever built. 
The extra twelve elements have been removed for testing purposes and is 
currently hand held and rotated as accurately as possible. 

I suspect that the poor gain might be due to the matching system because I 
was always unsure of the exact physical length of parallel quarter wave 
matching cable. The element lengths are spot on and the element spacing is 
within a millimetre of the design figures. The SWR, even after all this time, 
is still around 1.2:1. The Belden 9913 cable connecting the aerial to the 
radio is only nine metres long and, as best I can tell, has a about a half DB 

I would like to make e-mail contact with anyone who may have built this 
aerial or one of the other UHF designs by DK7ZB.


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