My opinion is that it adds unwanted horizontal radiation. Some will argue that
the current in the upper part of vertical radiator is increased, but so is the
current in the horizontal part, something seemingly overlooked by many.
In my case I *shortened* the loading wire to make the feedpoint capacitive and
then matched with a shunt inductor.
As a practical matter, this didn't improve the 2:1 match bandwidth one bit.
Without the matching and with my ground loss, the Z pretty much followed the 2:1
circle on the Smith chart with about 25 ohm at resonance and the reactance being
the big variable. With a 1/2" Heliax feeder and a tuner in the shack I was
good. With the L-network (series C furnished by the antenna and a shunt
inductor) I have a 50 ohm match at the design center and pretty much the same
bandwidth within the 2:1 circle. The real part of Z is now the big variable.
If I was manually adjusting a tuner, I might actually prefer the former. The
shunt L does provide a DC ground however, and the shorter wire fits my available
space better.
Wes N7WS
On 12/18/2018 2:01 PM, Todd Goins wrote:
So, Mirko brings up an interesting point. I can run out far more than 35'
horizontally. Should I make the wire a lot longer in that dimension? I was
working with the 130' (approx) total length I'd read about using for the
43' vertical's top loading wire. I know, I should be modeling this myself.
:-(
But if adding extra wire in the horizontal might help then that would be an
easy modification.
Any opinions?
Thanks,
Todd - NR7RR
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