On Wed, 31 May 2006 16:44:40 -0400, chuck wrote:

That it will not work if submerged as much as four
feet? From Roy's report on his NEC-4 modeling. It
is presumably based on the known skin depth of RF
at 14 MHz.

Hi Chuck,

You are drawing conclusions from different facts. These plates are
successfully put to this very purpose every day. There is no model
that says that a dynaplate submerged 4 feet "will not work." The
object lesson is that it will merely be a tie point to the length of
wire that is working every inch to it, and that the current in the
last inch will, in all likelihood, not see any benefit of that plate,
IF AND ONLY IF that wire travels through the water, or in very close
proximity to the water. The plate is not ineffective, it is merely
redundant.

If the wire travels through the interior of the boat, where most
transmitters reside, that dynaplate will conduct just as well, and at
as high a current as is necessary for a modestly efficient connection.
This is, after all, the whole point of installing these plates.

Other's have commented you can as easily wire to the engine (if you
have one) to create one great big gobstopper of a capacitor to the
water. Capacitors work quite effectively too, they are called
counterpoises. No engine? The same surface area in metal will
substitute. Too much surface area to equal effectively? Move the
capacitor plate closer to the hull, and reduce the area by proportion.
Does it matter your hull is fiberglass? None whatever.

What loss is it that I perceive? N6LF's results
show near lossless results with only four
shortened radials over seawater.

You still don't know how much loss there is through conventional
means, then, do you? "Near" lossless is not quantitative data.

Other studies have shown a single elevated radial
over land to lose less than one dB over a perfect
ground plane.

You have terrible sources for "other studies," then. That elevated
radial must be up a wavelength. How does this relate to "RF grounding
methods for sailboats?"

Well, what makes life interesting is that to
advocates of the other approaches, there are
obvious advantages.

You still don't have anything that amounts to more than testimonials.

Multiple resonant radials that cover the popular
marine and ham bands on a small boat are not seen
by all as simple.

Exactly. Why would you want to do it?

If you want a dipole, make a VERTICAL dipole, even a lousy one.
Certainly worthy of consideration. Many backstay
antennas are probably operated as half-wave
vertical dipoles (end-fed, of course)

Then it ceases to be a dipole.

I didn't address any matching issues at all that I
can see, Richard. Sorry if I misled you.

Every comment of yours that contains counterpoise, radial, loss, skin
depth, length of wire, or connection is a matching issue.

All of the alternatives utilize the same seawater
for propagation and the same vertical radiator.
They differ in whether there is any high-angle
radiation from a horizontal radiator, and possibly
in the magnitude of their "ground return losses."

If they all utilize the same seawater for propagation and the same
vertical radiator, they all suffer equally - it stands to reason there
is no difference given all the "sameness." It also stands to reason
by your assertion that they differ, that they do not all use the same
seawater or vertical.... Which is it? Let's skip that and cut to the
heart of the matter. How MUCH different?

Start with a conventional untuned vertical using a dynaplate and tell
me, in dB, how much better any other scheme is. Let's confine this to
a practical situation where the rig is under cover and inside the boat
and that you need two leads, one from the tuner antenna connection,
and another from the tuner ground connection.

73's
Richard Clark, KB7QHC

In article ,
Richard Clark wrote:

If they all utilize the same seawater for propagation and the same
vertical radiator, they all suffer equally - it stands to reason there
is no difference given all the "sameness." It also stands to reason
by your assertion that they differ, that they do not all use the same
seawater or vertical.... Which is it? Let's skip that and cut to the
heart of the matter. How MUCH different?

Start with a conventional untuned vertical using a dynaplate and tell
me, in dB, how much better any other scheme is. Let's confine this to
a practical situation where the rig is under cover and inside the boat
and that you need two leads, one from the tuner antenna connection,
and another from the tuner ground connection.

73's
Richard Clark, KB7QHC

This is exactly right. If they all use the same water for RF Ground,
and vertical, for the antenna, then the only difference is, "How much
coupling from the ground stud on the antenna tuner does each system give
to the water?" And that is the Thousdan Dollar question. DynaPlate,
Bonded RF Ground System, wires, radials, whatever, all, just make up one
side of the capacitor, with the water as the otherside and the distance
between is the dielectric. More effective coupling equals lower
impedance RF Ground. All this talk of Modelling is just so much FuFurrR,
for anyone who has installed MF/HF Marine Antenna Systems on these type,
wood or plastic vessels. Anyone with much experience in the field will
tell you, simply, get as much surface area as possible, bonded with
low impedance connections, (Copper Strap) and get it as close to the
water as possible. The Physics of building a bigger capacitor is:
Have as much surface area as possible, with the least space between the
plates. This isn't Rocket Science, it is just basic physics, and all the
crap about tuned counterpoises, and copper screens in the overhead, and
the like is just that...... crap...woun't work, never has, and never
will.
It doesn't take a NEC Modelling Software Package to figure this out, it
just takes some common sense and a bit of OJT Experience....

Bruce in alaska
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add a 2 before @