[amsat-bb] Re: DK7ZB 435MHz aerial question

Stan, W1LE stanw1le at verizon.net
Fri Jan 29 06:49:10 PST 2010

Hello Phil,

One big problem....

ALL elements must be installed to effectively test.
The V and H elements do interact, but that interaction is designed 
around by the designer.

Add the other elements with matching system and retest.

To prove this try modeling the entire element then remove all of the V 
or H elements.

Stan, W1LE    Cape Cod     FN41sr

Phil wrote:
> 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 
> loss.
> 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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