SSB backstay antenna, a new way

... written for Panbo by Ben Ellison and posted on Jun 30, 2005

GAM split lead SSB antennaI’ve never much liked the practice of inserting insulators in a sailboat’s backstay to create an SSB antenna; I want my backstays in one piece, thank you. Thus the Gam/McKim Split Lead Single Side Band Antenna looks like a much more sensible idea. The new design (bigger drawing here) fits over the stay, is easy to install or remove, and promises better performance with less likelihood of corrosion. Plus it’s “priced to compete with conventional backstay insulators (including swaging costs)”. Nice.

PS, 7/18: Rumor has it that Sail SSB expert Gordon West tested this antenna and found that it worked as well as an insulated backstay, even when fitted over the grounded stay of a steel boat. I’ve also seen reports that it many cases (depends on wire fittings) it is actually less expensive than the traditional insulator set up. Very nice!

Posted by Ben E on June 30, 2005 6:06 AM

Comments

Hmmm.... I'm not an atenna expert, but it seems like they are feed two wire parrellel to the backsty which means all three wires would be "hot" when transmittng so you'd have a random length longwire and you'd need some antenna tuner gear to deal with that I'm assuming. I've not looked in the backstay antenna lengths, but I always assumed (again with that word) they were sized to be tuned for the most appropriate frequency. Also it seems like it would expose anyone in the cockpit to more RF closer to their heads than the normal setup. Anyway, this sounds great from a rigging perspective but not so good on its face from a RF perspective. I'm curious what others think though because I'm a very rusty ham.

Posted by: Patrick at July 1, 2005 10:41 AM | Reply

Posted by: Patrick at July 1, 2005 10:44 AM | Reply

Interesting, Patrick, but my BS meter goes into the red zone when I read aggressive bluster like, "This split lead antenna is a scam. It won't perform worth a damn and is outrageously expensive" from a dude whose idea of good antenna is scrap wire hanging from a spare halliard. Might work ok for a delivery captain, but is that a rig you want to sail around with long term? Apple and orange comparison from an internet troll, I suspect.

Posted by: Ben at July 10, 2005 11:52 AM | Reply

IMHO there will be quite a lot more stray RF zinging around the cockpit with this antenna solution than with an inslated backstay. The dual parallel wires simply couple the RF into the wire backstay. The resulting non-resonant antenna element will be comprised of the backstay, both antenna wires, the stern rigging tang, ground plane, the mast and effectively the whole rig...shrouds and all. With an insulated backstay, the 23 ft section that is between the insulators, together with the single conductor high-voltage feedline from the antenna tuner, is chosen to be harmonically related to the majority of the SSB channels desired. Extra metal hanging off the ends of the antenna....the mast, shrouds etc will all be directly RF driven from the tuner. There is enough parasitic RF current zinging around under an end-fed random length SSB antenna without actually connecting the antenna directly to the sailboat's rigging! I'll hoist a 23 ft wire on a halyard while saving for a pair of quality insulators. http://64.70.221.24/members/addpubs/sanctuary.pdf

Posted by: Silverheels III at February 15, 2007 12:56 PM | Reply

It's better to build a couple of stainless steel vertical dipoles than to pursue ANY kind of insulated backstay arrangement. You'll get much better performance.

Posted by: vronp at February 20, 2007 8:44 AM | Reply

I noticed that this design runs braided copper thru HDPE. If for a backstay(or double backstay) you were to use amsteel(which is a hollow braid), some other suitable HDPE or UHDPE and run a wire for an antenna thru it. Let's also say where the wire stopped and started you kinda pushed the HDPE together like a Chinese finger handcuffs and worked in some insulating goop(please suggest what you think best), with the rubbery characteristics of boatlife,waited until it slightly cured and then stretched it(loaded it till full cure). Wouldn't that work. It seems that type of line is also being used on it's terminal ends with a loop and lashing. Couldn't the loop(eye) go around a ceramic insulator, and then lashed, like the kind you sometimes see where telephone guy wires attach near the ground. Also if the insulating idea worked what would the effects be of the slight salty moisture, surrounding the antenna to a slight depth, what would the effect be on the signal? Also there is the benfit that it is more insulated if the antenna was touched.

Posted by: Bob at June 8, 2007 10:24 PM | Reply

Efficiency looks best in copper....

Material Resistance
(ohm-cmil/ft) (ohm-cm)

Aluminum 15.94 2.650 e-6
Brass 42.1 7.0 e-6
Carbon (amorphous) 3.8-4.1 e-6
Constantan 272.97 45.38 e-6
Copper 10.09 1.678 e-6
Iron 57.81 9.61 e-6
Manganin 290 48.21 e-6
Molybdenum 32.12 5.34 e-6
Nichrome 675 112.2 e-6
Nichrome V 650 108.1 e-6
Nickel 41.69 6.93 e-6
Platinum 63.16 10.5 e-6
Stainless steel (304) 541 90 e-6
Steel (0.5% Carbon) 100 16.62 e-6
Tungsten 31.76 5.28 e-6
Zinc 35.49 5.90 e-6

Posted by: Doug at October 4, 2009 11:38 PM | Reply

Posted by: John Burns at June 24, 2010 1:11 AM | Reply

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