wrote:
You wrote:
In article ,
(Richard Harrison) wrote:

If "skin effect" prevents penetration to a copper plate on the hull,
fine. RF has then made the transfer to the sea at a shallow depth.
That`s the goal.
Bull****, where do you guys come up with this stuff....Skin Effect is a
a Boundry Thing, and the hull of the vessel is the "Boundry of the Sea
Water" even if it is 10 feet below the sea surface.

Finally someone gets it! This is what Roy said way back in his first
report of his modeling, that the ground plate if fastened to the hull
will be on the surface of the water even if it happens to be several
feet below. The other side of the ground plate is air. In other words
the hull is displacing the water. Unless of course the boat has sunk.

It is interesting to speculate about the
proportion of displacement currents passing
through the air to the inside of the hull and then
through the hull to the grounding plate, vs. the
proportion passing from the surface along the
water-hull interface to the Dynaplate.

As Roy pointed out, one reason seawater "works"
despite its low conductivity relative to copper is
that a high percentage of the "ground" return
current is concentrated very close to the antenna
where path conductance is high. If the water path
from the surface to the Dynaplate is vertical
(four feet) does that mean return currents must
pass through four additional feet of seawater and
thus will encounter greater losses than if the
Dynaplate were at the surface?

Or will the vertical water path "collect" the same
or even greater return currents than a horizontal
water path? I've heard of radials sloping up and
away from the antenna at 45 degrees, but 90
degrees? (Assumes tuner ground terminal directly
adjacent to Dynaplate on other side of hull) Ought
to be easy to model.

Interesting, no?


For the guys that are referencing the N6?? Article about very short
elevated radials over sea water; please note that he is saying those
short elevated radials are tuned with loading coils.


Yes. That is what he reported on his modeling.

Elevated radials will not work unless they are 1/4
wave resonant or
tuned with a loading coil.

This is not at all obvious to me except at a
semantic level. And lest anyone misunderstand,
Gary is not suggesting that N6LF made that statement.

Is an automobile body (on land) conceptually
analogous to non-resonant, elevated radials? Does
it work? Would it work less well over seawater
(let it levitate or make very quick QSOs)?

Would a random length whip on HF work with a tuner
and a single, non-resonant wire about 25 feet
long, in lieu of the auto body? Would it work less
well over seawater?

If you're with me this far, the next question is
"how much better or worse?". And then on to the
other tradeoffs: radiation patterns, safety,
simplicity, RF coupling, etc.

Alternatively, we can explore why it won't work.


73
Gary K4FMX


73,
Chuck
NT3G

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