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ANTENNA AND GROUNDING CONSIDERATIONS
ANTENNAS & TUNERS
If your Icom SSB transceiver is going aboard a sailboat, you
may either use an insulated backstay an insulated sidestay,
or a non-resonant white fiber glass whip antenna off the stern
to make up your antenna system. Your best range will be
from an insulated backstay because of the long length of the
antenna "radiator" which is that portion within the top and
bottom insulators. Have your rigger put the top insulator
about at least 3 feet down from the tip of the mast. Have your
rigger install the bottom insulator at about eye-level when
you're standing back aft. (This length between insulators
should not exceed 120' or be less than 23'.) If you decide to
go for the non-resonant whip antenna, the antenna usually
goes at the extreme stern and mounts either vertically or
raked back at about a 45-degree angle.
These non-resonant antennas may be tuned by the ICOM
automatic antenna tuner that matches the Icom SSB trans-
ceiver. The tuner goes back aft, in the lazarette, or as close
to the antenna as possible. It is completely weather-pro-
tected and can easily take the punishment of being aft and
below deck where you're probably also going to store wet life
preservers, foul weather gear and the like. The tuner inter-
connects with the Icom SSB. Full details are in the tuner in-
struction (installation) manual. We suggest you use
"GTO-15" high voltage lead-in wire from the single wire out-
put of the tuner to your insulated backstay or to your non-
resonant whip. This high voltage wire won't break down in
wet weather or sunlight. Use stainless steel hose clamps to
attach the wire to the insulated backstay. If you decide to use
a non-resonant whip, attach the single wire with a lug to the
feedpoint at the base of the whip.
More about the importance of grounding in a moment.
For those of you with a powerboat, a whip antenna approxi-
mately 16 to 20 feet long is what you'll be using with your
new Icom SSB. The most common set-up consists of the
white fiber glass non-resonant whip antenna that is auto-
matically tuned with the ICOM automatic antenna tuner. Sim-
ilar to sailboat installations, the tuner is hidden out of the way
in the flying bridge area or below deck near the base of the
whip. GTO-15 wire interconnects the whip to the automatic
tuner. The tuner is fed with coax (RG 213) and a control line
from the back of the Icom SSB wherever you plan to hide the
auto-tuner. Remember, the ICOM automatic tuner is fully au-
tomatic, so you can put it completely out of sight!
We suggest you check with the dealer that sold you your
transceiver to purchase the ICOM automatic tuner as well as
a resonant or non-resonant whip antenna assembly. Dealers
that sell ICOM equipment usually have these accessories on
hand.
THE IMPORTANCE OF GROUNDING
Please read this! If you are looking for "super range" with
your new Icom SSB transceiver, we have some tricks that
will give you the same kind of range as globe-circling cruise
ships, super tankers, solo sailors, the Navy and the Coast
Guard. Surface area to the sea water and the use of copper
foil exclusively throughout your RF ground system is the
combination that gives you commercial-type "super range."
The sea water acts like a diving board or side of a pool for a
diver and a swimmer— it gives your signal a solid surface to
push off from. This is technically called a "counterpoise", and
it's the absolute necessary "other-half" of your antenna sys-
tem that must be achieved for your overall single sideband
system to work well.
It's not that hard to develop your own sideband RF ground
system in just about a day's time, and you may even find that
most of the RF ground system is already installed so you
have little to do but to tie everything together with copper foil.
Read on, please, and let us show you how easy it can be.
NON-TECHNICALLY SPEAKING
If you plan to have a technician or a technical friend install
your sideband system, have him skip this part and begin
reading at "Antenna Ground Principles, Technically Speak-
ing." If you plan to do the installation yourself, and this is the
first one you've done, read on!
The water that your boat sits in is the ultimate ground coun-
terpoise. There's none better. Commercial AM broadcast sta-
tions on the coast usually put their giant antenna system in
the mud flats of a local bay for good range.
Some boat suppliers put ground foil and ground screen in
the cabin overhead. This is true on expensive powerboats,
and is sometimes found in a few sailboats. While this type of
overhead RF ground system is better than nothing, it still
lacks the capability of coupling with the ocean or lake as the
ultimate water ground system. A far better RF ground sys-
tem would be the following:
• 9.3 sq. meter; 100 sq. ft. area of foil below water line
• Metal water tanks
• Lead keel
• Foil radials
• Interconnected through-hull
The whole idea is surface area— and this is why a keel bolt,
underwater tanks, through-hulls, and anything else flat and
next to the water does such a good job. Now we know your
next question, "But doesn't a good ground actually have to
be in contact with the water?" Not at all! At radio frequencies
(RF), your underwater ground counterpoise sees the water
in a capacitive way, which gives just as good a ground effect
as if it were actually touching the water!
Now here's another very important point, no round wires for
RF ground! Even if you use welding wire the size of your
thumb, you cannot achieve a good ground counterpoise with
round wire. In our "Technically Speaking" section, we'll tell
you why, but, in non-technical terms, round wires tend to
cancel out at radio frequencies, and they look invisible as a
ground counterpoise interconnect. This is why copper foil
must be used between the chassis of your transceiver to
your ship's RF ground, as the chassis of the automatic an-
tenna tuner to ship's RF ground.
Your better marine electronic stores that sell ICOM equip-
ment will also sell three-inch wide, super-thin, copper foil for
grounding. In a pinch, you can use one-inch wide copper
plumber's tape. Three-inch is better. Note: A three inch strip
mounted three inches away from another three inch strip of
copper foil looks like a nine inch strip to a radio wave.
It's going to take you about a day to work this foil below
decks and below the water line picking up anything and
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