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I have a ground plane that is a 132 foot vertical radiator (Rohn 25)
with 3 154 foot radials. The insulator is at the 60 foot level of the
tower, along with the radials. The radials are floating, and connected
to the braid of the coax feed line. The vertical radiator connects to
the center conductor of the feedline. A 1:1 current balun is in place
at the feed point. The radials slope at a 20 degree angle from 60 feet
down to 10 feet AGL. The system as installed resonates on 1520 khz with
a vswr of 1.16:1
How do I move the resonant frequency up to 1830 khz? I have tried
several series caps at the feed point, but am getting nowhere other than
into great physical shape climbing the tower every day! I am stuck with
the lengths above as the radials are also guy wires.
Any ideas on what a tuning/matching network at the feedpoint would look
like?
If someone has time to model this antenna for me, I would be most
greatful. Directly under each radial is a ground screen consisting of
3-160 foot radials.
All ideas and inputs appreciated!
(((73)))
Phil, K5PC
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