Thom,
did you measure the feed point impedance ?
I doubt this antenna is electrically an half wave one, it's probably a sort
of quarter wave vertical radiator with a top loading (the sloping wire).
The electrical lenght of this antenna lenght should be around 120° instead
of the 180° as you think.
The complex impedance at the base should be some 200 + Jx and
probably better matched (more bandwith) using a series capacitor equal
to -J and a 4:1 balun (may be 6:1).
This doesn't prohibit the antenna to work efficiently as it's installed.
73,
Mauri I4JMY
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