> I built 1/4 wave and 1/2 wave verticals for 20 meters.
> The 1/4 one one had 32 1/4 wave radials. The 1/2 wave
> one had only the shield of the feedline as a counterpoise.
> I did an A/B test using received signals off the air.
> I could not discern any consistent advantage of one
> versus the other. YMMV.
>
There's no mileage to vary because a receiving test is hardly any
kind of accurate assessment of antenna transmitting efficiency. Put
up a half wave vertical and put in a ground system of at least 60 half
wave length radials. Feed it with around 10 watts and conduct a field
intensity measurement from around 3 to 5 miles away. Do the same
thing, this time with the ground system completely disconnected from
the ground common point. Let us know what you see. That's about the
only decent test. And as Paul mentioned, every medium wave station
with a 190 degree tower would have gladly saved tens of thousands of
dollars in ground system costs if this were not true. By the way,
since it's a voltage fed vertical, you actually should have mesh
around the feedpoint to serve as an electrostatic shield. But for
ham, I'll let that one slide.
It's a shame QST has perpetuated the myth of the vertical unbalanced
antenna near ground that doesn't need any kind of shield against
earth.
73
Rob
K5UJ
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