Having walked around on the beach with a battery K2 listening to incoming
signals on a short antenna, walking 50 feet from the water drops signals
multiple S units. Over the beach there is an absorption zone starting at
the sand at water’s edge which goes higher and higher the farther from the
water. This isn’t EZNEC, just observation on Core Banks, NC during a number
of IOTA contests. Very easy with all those signals to hear what was going
on.
On 40m there was a big difference between a doublet at 40’ and 50’, back
from the beach about 200’.
Apparently sand wetted with salt water is quite lossy.
But even not optimal at the beach smacks the snot out inland locations.
Which IMHO explains the wide variety of beach-based reports.
Also a very short vertical radiator away from water’s edge will not hear as
much as a tall one as the tall wire has more intercept outside the
absorption zone next to the sand.
It’s really quite a complex subject.
73, Guy K2AV
On Tue, Dec 20, 2022 at 7:28 AM <n4is@comcast.net> wrote:
> Hi Frank
>
> You wrote " . A vertical over a salt marsh or within about a wavelength of
> salt water will produce
> 6 dB or more of gain at low angles compared to a vertical with poorly
> conducting soil in its reflection zone
> "
>
> The assumption that "next to the water" is the same as "in the water" , is
> a
> not right. It is not the same !
>
> I listen to George signal with vertical "in the water " and the 10 db
> difference in signal is real. Moving the antenna on the beach and you lose
> 10 db or even more on practice, not on paper.
>
> I see that on my S meter more than a dozen times.
>
> George has a vertical on his house in Miami, the ground plane is just a
> plate down the water. The vertical is made with fiberglass pole 18m high.
> My
> antenna is a full size vertical with a good radial system over the
> Everglade
> land, if I dig 2 Ft I have water from the Everglade underground river.
>
> George can run a pile up from Europe with 10W, I can keep up with him
> running legal limit power. We are talking about 160m only.
>
> 73's
> JC
> N4IS
>
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