On Thu, Apr 2, 2015 at 12:51 PM, Kenneth Silverman <kenny.k2kw@gmail.com> wrote:
> One time in Jamaica I ran a test between two 10m verticals: one right on
> the sea wall, and another 100' back and spaced about 200' apart (enough
> that they shouldn't have much interaction at 10m). The vertical on the sea
> wall was at least 2 S-units better than the one 100' back, and often much
> more.
These kinds of results are like my walkabout-on-the-beach results with
my Elecraft K2/10/battery plus short antenna. I was listening during
the IOTA (lots of stations) to 40m CW signals which should be low
angle: Europe in early afternoon. Kenny was talking about a 10-12 dB
differential. In my case, I saw variation on a given station from
"569" or "559" to uncopyable in the noise. While that is as
quantifiable as jello, it is a LOT of loss however fuzzy the number
may be. Quite adequate to inform antenna placement decisions.
If someone offered me a bucket of gold coins that someone loosely
estimated at 50 to 70 pounds, I'd take it regardless of the lack of
precision measurement :>)
The big gorilla in the room remains invoked losses in the "ground"
media, whatever it is, however close or far from the antenna, however
invoked, and how to avoid same. At the beach, sand is a terrible
ground media, thus transiting wonderful to awful walking out of the
water up the beach.
This still applies to an ocean view "cliff-side" QTH. To minimize
ground loss directly underneath, push a cliff-side antenna as close to
the cliff as it may be supported. For counterpoise, erect an FCP
parallel to the cliff edge. The point is to get the sea water
reflection, with as little ground loss penalty as possible. You can
still screw up the advantage of a cliff-side QTH by not paying
attention to the gorilla.
A friend who has a saltwater fronting house in Florida has tried a
multiband vertical at his low sea-facing wall, back ten feet from the
water, and out at the end of the pier. The pier location is a clear
all around winner. There is still dirt below the antenna at the wall
location. Eliminate the gorilla.
73, Guy
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