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.
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.
participants (2)
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Phil -
Stan, W1LE