Eric Fairbank wrote:
Icom needs to modernize their thinking and get rid of their "old school"
installation guides. Wire radials are the way to go on your sailboat. Not
copper foil or wide copper strips, just plain old 14 gauge wire radials. I
suggest you read some of the threads about this on the Maritime Mobile Ham
Forum from people with real world experience with marine HF installations.
You'll find the answers to your questions the

http://cruisenews.net/cgi-bin/mmham/webbbs_config.pl

Eric

"Will" wrote in message
...
I want to set up a hf antenna for my sailboat.

I have read various guides from Icom etc.

They suggest running copper foil to a Dynaplate and use sea water as the
ground. How can this work when the Dynaplate is below sea water?

Is sea water equal to copper wire radials as a RF ground system?

Does sea water make a good enough ground without radials?

How can a piece of copper metal about 1 ft square equal several radials
laying on the boats deck?

Why do i have to use copper foil when most other people suggest using
ordinary copper wire?

Over seawater what would be the best number of radials to use considering
that maximum length i can run is 40 ft. I am planning to use a backstay
antenna with a SGC 230 Tuner.

All ideas and comments appreciated.

Will



As others have pointed out in other contexts, it is more useful to think
about an HF "radial" on a boat as the "other half" of a vertical dipole,
rather than as an "RF ground". Even with substantial asymmetry (which is
almost a necessity, given the proximity of the horizontal "radial" to
the sea), most autotuners can match an off-center-fed, L-shaped
configuration easily. It is not necessary that the horizontal "radial"
be resonant for good performance.

Disregarding the balanced, center-fed dipole, the most common
alternative approaches to a vertical antenna are 1) the use of the sea
as a large ground plane, usually with a Dynaplate, and 2) the use of a
large conducting surface (traditionally specified as a minimum of 100
square feet) inside the hull. This surface can also be thought of as the
other half of an asymmetrical dipole. It is often connected to the sea
through under water metal parts such as the keel, in which case it
constitutes a kind of hybrid involving both 1 and 2.

Comparative test data on these systems are quite difficult to obtain and
virtually all of the information available is anecdotal, rarely
reproducible, and often contradictory. Analytical studies of these
systems, particularly as applied to fiberglass yachts, are also scarce.

Unless you really know what you are doing, I second Me's advice to find
someone with a lot of experience for assistance. Of course,
experimentation is a good thing, too.

Good luck.

Chuck