In my opinion Hy-Gain designs are very old and going with a OWA would be a
much better approach. Plus the 203BA and 204BA that I previously owned
liked to shed element tips. My homebrew 5el 20m OWA beams with a 52' boom
that I last built from scratch have 1:1:1 SWR across the whole band.
If you wish to use a hairpin match, you probably should connect a 1/2 WL
multiple coax to the feedpoint and check the impedance with an analyzer.
Then you have to play with the match and DE length to get 50 ohms at the
desired frequency. The parasitic elements control the bandwidth.
GL,
John KK9A
Yuri ve3dz wrote:
Hello,
I recently modified my old 204BA using the BV204CA file (YW, Yagi for
Windows by N6BV) from the ARRL Antenna Book.
I moved Driven Element and Director 1, changed the element tip lengths
where necessary and changed Hairpin match length according calculations.
According to the computer model the calculated SWR is 1.09:1 on the
resonant frequency of 14175, and 1.40:1 on the edges: 14000 and 14350 at
the 80' height.
Hairpin spacing that used is 12 inches (different from the original one,
which was 6 inches).
In reality, I have SWR of 1.05:1 on 14090, which appears to be my new
resonant FREQ now, and 1.6:1 on 14000 with 2.6 on 14350.
Why is it so narrow?
What am I doing wrong? Should I use original hairpin rod spacing of 6"?
Old variant of this antenna was wider (better broadband)
Any advise would be greatly appreciated.
--
73, Yuri VE3DZ
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