Looks like you have a double dip in impedance typical for staggered tuned
antenna. Is one of the elements "pulling" it or maybe effect of the other
balun and coax within the antenna? (It is in the same plane as the feed and
might be resonant causing the "other" dip. Something like OWA Yagi.) Try to
remove it or check the element dimensions.
73 Yuri, K3BU
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I thought the SWR curve looked strange as well. The SWR has a weird
curve across the entire band. The antenna is actually a 4 element quad.
Its fed with a W2DU style VHF 1:1 balun. The coax is a short run of
RG-8X. The RG-8X uses PL-259s on both ends and I soldered a SO-239 onto
the coax for the balun (see pictures). Any issue with using PL259s and
a SO239?
Here is a picture of the feed system:
http://www.wu2x.com:8888/usenet/P1010062.JPG
Here is a picture of the antenna under test:
http://www.wu2x.com:8888/usenet/P1010058.JPG
This is the data graphed out, so its easier to see:
http://www.wu2x.com/usenet/ReadingA-ReadingB.htm
I took measurements with it fed for vertical polarization and
horizontal polarization. The results are both shown on the graphs.
-Scott, WU2X