There should be no problem at all with some of the antenna being below
deck. It would be good to keep it away from metal stuff of course.
Longer horizontal runs tend to raise issues, though. Probably a greater
chance of coupling rf into the boat's other electrical systems, and a
long run of 20 feet or so (say from the backstay to a nav station
amidships) can radically alter the radiation pattern. Maybe for the
good, maybe not. And that is the main reason that manual tuners are
questionable choices for use with backstay antennas. Nobody wants to try
to manually tune a backstay antenna located at the stern if the rig is
15=20 feet away.

To avoid this run, some of us have resorted to loading the shrouds (and
the whole rig as well) with an L-network quite successfully. I believe a
separate wire run up a flag halyard would be an easier antenna to tune,
but it would introduce other issues.

As Gary has said, it is difficult (but only mildly so) to get a resonant
quarter-wave in a backstay. It would probably require an antenna
impedance analyzer to find resonance. Make it a bit short and add a few
turns of wire (cheap and reliable) to bring it to resonance.


Chuck



Bill Turner wrote:
On Sun, 28 Nov 2004 21:15:13 GMT, Gary Schafer
wrote:


It's kind of difficult to get a resonant quarter wave into a back stay
as you don't usually know where ground is. Ground can be any number of
feet from where the feed point is on a boat. Every thing above real
ground is antenna.


__________________________________________________ _______

Correct. For simplicity, figure the feed point is right where the coax
shield connects to the ground plane. As you said, everything above that
is antenna. On a fiberglass sailboat, the hull is quite transparent to
RF on HF frequencies, so the presence of a few feet of antenna inside
the hull is of no consequence.

--
Bill W6WRT