SSB Antenna

[ORIANA]

I am installing an Icon 810 SSB. I don''t really want to install a long wire on the back stay. Does anyone have any information on a 23'' whip antenna or anything else that seems to work. Thanks for any help.
Hugh

[gstraub]

A 23'' whip should work fine for most purposes. It will have somewhat lower efficiency than a longer insulated backstay at lower frequencies (like down on 4 MHz). As antennas get shorter, like many amateur mobile antennas, most will start using some sort of loading which consists of a coil or helically winding wire on a form. This helps the antenna tune better on lower frequencies and may slightly increase radiation efficiency, but introduces additional losses. I don''t think you would be disappointed in the performance of the 23'' whip.

Gerhard

[GordMay]

I may have misunderstood your query - if so I apologise.
The insulated back stay IS the long line antenna.
The insulated back stay is, by far, the BEST antenna for a sailboat - simple, effective, safe, and unobtrusive.
See:
www.sgcworld.com
Go to "Manuals", and click on "HF SSB Users Guide"
Regards,
Gord

[Koene]

It sounds like you may be reluctant to use your backstay due to installing the insulators. We have returned from 3 years cruising and have used the single side band a lot with great results. I have used a seperate thin copper wire succesfully. Our boat is steel and that does help performance due to the ground plane. I also installed the tuner outside on the radar mast. Many people forget that the antenna out becomes part of your antenna. By installing your tuner outside you could avoid a lot of signal loss depending on your boat material. If you do install your tuner inside the boat have your antenna lead away from ground sources. Do not use wire tabs to lead it up the backstay you do need some clearance. In order to get the best performance you need to worry about your ground setup. Most boats ground plate is to small. You may want to add other sources of metal to create a better ground plane.

Ruben

[GordMay]

Further to Koene:
Standoffs, either for leadin wire to backstay or for separate wire antenna, can be fashioned from small PVC pipe.
Plastic Pipe should be larger diameter than backstay.
Cut Pipe into approximately 1" pieces, using a large diameter drill bit or hole saw. Thus, the ends of the resulting spacers are concave.
Insert a Tie Wrap (wire tie) into the spacer, wrap around the antenna wire, and back through pipe. Wire is now held captive to spacer.
Lay other end of spacer against backstay, and complete wrap around stay, pulling very tight. Trim excess tie-wrap end CLOSE to retainer (gently file end, if neccesary).
Use LOTS of spacers - perhaps every 8 - 10".
Regards,
Gord

[ORIANA]

Thanks everyone for the information. I would rather use a 23'' whip but running an antenna up the backstay and seperate the two sounds even more promising. I will look into this using the PVC spacers. I don''t have a copper ground plane installed. Is this going to be a problem and should this be glassed in the fiberglass hull. Thanks Hugh

[GordMay]

Your SSB will require a good RF ground (counterpoise).
A good RF counterpoise system requires 100 square feet of grounded metal(s) below the waterline, and could consist of:
1. copper foil, below the waterline. Could consist of 3" wide Cu foils @ 3" apart (simulates 9" wide strip) running fore and aft. Fix the foil to the hull, using epoxy, glue, etc.
2. metal water tanks
3. engine block
These all provide a "capacitive" couple to the water.
4. external ground plate
5. lead keel (external)
Wire & cable are useless RF Gnding materials.
Hope this helps,
Gord

[i670684]

Gordon West ran some tests and came to other conclusions, namely that a huge counterpoise/ground system was not needed. I haven''t tried what he recommends, but here''s a link to some more info. I can no longer find the original report. Bottom line is I would try it without installing an extensive ground system. Gordon used the existing bonding system and, through metal thru-hulls seemed to get a reasonable ground.

http://www.sailnet.com/collections/cruising/index.cfm?articleID=suelar0175

[gstraub]

I do not agree with everything Gordon West says, however, as an antenna design engineer for high power mediumwave and shortwave antenna systems, this is one thing that I agree with him on. What many people do not realize is that saltwater is one of the best ground planes there is.

A good low inductance connection to the seawater consitutes about a good a counterpoise as you could ever have. Sitting on top of thousands or square miles of highly conductive ocean, a little extra copper in the bottom of the boat is not really significant. If there is no direct low impedance connection to the saltwater, then the extra copper provides capacitive coupling to the ocean ground. If the antenna feed point (ie the tuner output) were located a couple of stories up on a fiberglass boat, then a counterpoise on the boat would take on more importance because it would be difficult to get a good low impedance ground connection, and in this case, it would operate as a true counterpoise. However, this is seldom the case on the type of boats we are talking about.

Gerhard

[kimberlt]

our Amel came equipped wity a whip antenna
and 2 copper ground plates mounted on the outside of the hull.
while crossing the atlantic we had no problems doing ssb-e-mail and speaking to our weatherman in canada.
fair winds,
eric