JVL loop yagi VNA test

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G4GHD
Posts: 40
Joined: Sun Nov 12, 2017 12:18 am

JVL loop yagi VNA test

Post by G4GHD » Tue Aug 09, 2022 1:05 pm

After a few decades on the roof mast, I've now taken down my original 24cm G3JVL loop yagi and thought I'd check it out on my NanoVNA. The socket has been cleaned up and the tests were done in the clear (as best as I can manage anyhow). Results seem disappointing to me, I'd expected the SWR curve centred on 1.282GHz to be slightly wider and deeper. The other dip at 1.367GHz SWR is what I was hoping for at the lower frequency. Note the impedances too.

Obviously actual antenna performance is not defined by SWR alone, but I was surprised by the results. I'd be interested to know how they compare with others, should anyone have done such measurements.

I do remember when the antenna arrived, G3JVL enclosed a piece of paper detailing his suggested adjustment of the small tabs next to the driven element for improved SWR. Of course, I no longer have that :roll:
1367 MHz.jpg
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1282 MHz.jpg
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Last edited by G4GHD on Wed Aug 10, 2022 3:00 pm, edited 1 time in total.

G4GHD
Posts: 40
Joined: Sun Nov 12, 2017 12:18 am

Re: JVL loop yagi VNA test

Post by G4GHD » Wed Aug 10, 2022 2:59 pm

FWIW, results with the 13cm version.
2473MHz.jpg
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2403MHz.jpg
2403MHz.jpg (553.36 KiB) Viewed 2523 times

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