Dry sand decrease ground reflection over moist soil around the beam direction
of a directed antenna (2 to 6 wave lengths). I found out no advantage directly
below the antenna. More than 25 years ago I tried on my first tower (90 ft up)
a radial net with more than hundred wires, ea. a quarter wave long on 20 m.
After removing the wires NOTHING was to observe. Efficiency, swr and Z
was absolute equal than using a radial net. And of course no effect on that
with
or without a rood grounding system directly on the tower. Dipoles or loops
DON'T NEED a HF ground directly on the tower!
But if I would like to use the tower as a vertical antenna with for 75 Meters
the
advantages with wire radials will be dramatically better. HF ground direct down
the antenna is only important for antennas using as second pole the ground.
73,
Werner
DJ2HZ
measures wrote:
> >
> >At 04:11 AM 10/8/99 -0700, measures wrote:
> >>
> >>>
> >>>I agree hundred percent of Rich's and Phil's opinions. A HF ground is not
> >>>necessary for yagi (dipole) or quad antennas on towers. This only needs a
> >>>good
> >>>lightning ground.
> >>>More important is a free area around the directional antenna. A moist soil
> >>>will improve the reflected signals.
> >>>
> >>On the other hand, moist soil also improves reflections that result in
> >>cancellation.
> >
> >Nope to both.
> >
> >"The effect of ground reflection on antenna performance is dramatic.
>
> ? Would dry sand increase or decrease ground reflection over moist soil?
> >.......
>
> - Rich..., 805.386.3734, www.vcnet.com/measures.
>
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