On 9/7/2012 7:51 PM, Chuck Gerarden wrote:
I have read in ON4UN's book
that the radials should be offset from each other and not connected
between each vertical. Can any one confirm this?
As it happens, I have a similar installation here -- a 115 ft tower with
sloping wires insulated from the tower and fed from the bottom against
four elevated radials for each vertical. I feed one or the other, but
not both. NEC shows some interaction between them, which I am
controlling by shorting the feedline of the unused antenna in the shack,
making the feedline a shorted stub. LOTS of NEC modeling went into this.
:) The radials are installed as ON4UN recommends -- no connection
between the two verticals.
My radials are elevated about 16-18 ft (3 ft at the feedpoint, rising
gull-wing style as the leave the feedpoint). I originally installed them
at about 4 ft, and the efficiency was poor. This summer I raised them
and the efficiency seems better. Since the tower is a passive reflector
(thanks to a SteppIR and a 22 ft 2M Yagi on an 8 ft mast on top), I have
eight on-ground radials on it, and may add more. The tower and its
radials are grounded, the elevated radials are not.
73, Jim K9YC
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