In article ,
"Jerry Peters" wrote:

Hello group - This is my second post regarding SSB installation

Three quick questions if I may. First, I understand that round wire is
invisible in the grounding system and flat sheet or screen copper is
required/preferable. If screen is used, what are the critical
characteristics - grid size, wire size, etc? I am concerned that the screen
is just a bunch of small round wires. Second question is related. It is
recommended to use several isolation capacitors for establishing the
connection to the engine or other DC ground to avoid a DC ground loop
between the antenna system and the radio. Once again, aren't the lead wires
to the capacitors round wire and won't they "disappear" electrically? Third,
is it important to keep the ground plane below the water level?

My current plan is to laminate the interior of the hulls (catamaran), above
and below the water line, with copper "insect screen" and tie it to the
engine ground, water tank, etc with 3" copper straps and pull it all back to
a single point at the tuner.

Opinions?

Jerry Peters



MF/HF Low Impedance RF Ground Systems are not that hard to understand,
if one just uses a bit of common electrical reasoning.
First, The water that your floating in is the best ground around.
Second, Coupling your Antenna Ground to that water is what we are
really talking about in these discussions.
Third, there are two ways to accomplish the above said "Coupling".
Directly connecting the Antenna Ground to the water, and capacativly
coupling the Antenna Ground, to the water. The former works really well,
but electrolysis will eat your connections Big Time. DynaPlates are your
friend. The later is what most plastic and wood vessels use to
accomplish this. Think of the water as ONE plate of the two that are
required to build a Capacitor to couple the RF to the water. Think of
the strap, screen, metal fueltanks, metal water tanks, keel metal,
ect, as the other plate of the capacitor.
Now how do we get MORE capacitance between the two plates? First, move
the two plates CLOSER together. Ie get the screen, straping, tanks,
keel, as close to the water as possible. Like right next to the hull.
Second, Add more SURFACE AREA to the plate inside the hull. More screen,
more tanks, more metal, more, more, more.
With enough coupling your Antenna Ground should be capable of good
efficency clear down in the 1.6 Mhz range. With a marginal RF Ground
your going to have to rely on 4 Mhz and above for communicating.
Your autotuner will take care of the antenna tuning, but it NEEDS a
really Good RF Ground to work PROPERLY. Autotuners have one very
LARGE failing. They CAN"T tune frequencies close to the 1/2 wave
natual resonace frequency of your antenna. Usually about 150 Khz
on each side, higher and lower. So you must design the antenna
so that the 1/2 wave point is in at a frequency that you AREN'T
EVER going to use.

end of Lectu RF Grounding on Nonmetal Hulls - Part 1


With a metal hull, this is not a problem as the whole hull is the plate,
insulated by the bottom paint from the water, and protected from
electrolysis by your zincs.

Bruce in alaska
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add a 2 before @