Backstay antenna length decision

[derfy]

Okay .. enough "over thinking" and "fish frying". Thanks to all for the great reference info, particularly from John and Brian.


Will post a final report in a few weeks when I am done installing and tweaking.



Cheers

[ka4wja]

derfy,
Please know we are all here to help....anytime...
And, I personally think your willingness to learn (asking questions) is GREAT!!

Originally Posted by derfy

Okay .. enough "over thinking" and "fish frying". Thanks to all for the great reference info, particularly from John and Brian.

Will post a final report in a few weeks when I am done installing and tweaking.

Cheers

My main advice, however, is to not "over think" the basics that have long been established by good engineering practices and real-world experience, but rather spend more time learning the intricacies of radiowave propagation and HF radio operations!

This is something that is often overlooked and quite honestly, except for the wiring/connections/commissioning of your communications system, is THE primary determiner of how much success the average sailor attains with their HF communications...

Hands down this is what is vitally important....most sailors spend years learning and honing their sail trim skills/techniques, many hours/days/weeks learning navigation, diesel maintenance, head repair, etc. etc., but spend little time at all studying / learning HF radiowave propagation and HF radio operating techniques....(including lots of real-world experience / time on-the-air)...

And, this why sometimes my words can be seen as rather strident (but hope I'm never rude?)...

So, derfy, please continue to learn and ask questions....just look at more than just these items / subjects...

Fair winds

John

[plebian99]

While any random length of wire works, if you are a long distance sailor you need to consider the efficiency of the overall antenna system.


If you are mainly a coastal cruiser and hugging the coast of your own country then the backstay length and how much radiated power you are wasting is hardly an issue if you are using frequencies blow 12mhz.





If you are migrating into the deep Pacific and Indian ocean I would think more carefully about backstay length. especially considering how poor propagation is at the moment.





In general on the high frequencies best efficiency for long distance communications comes from keeping your radiatiating angle and lobe below 15 degress. In general once you go over 5/8 ths wavelength in length you start to split the lobe and get a lot of high angle of radiation from your antenna which wastes power sending it to where it is doing no good for your signal strength.



In general its 5/8X984/ frequency. So if the highest frequency you are planning to operate is 15mhz then the backstay should be optimised for the length of no more than 41 feet. The difficulty comes when trying to avoid the 1/2 wavelength on 8mhz and 12mhz so the magic length will be a combination of trying not to go above 5/8th wavelength and avoiding the half wavelength on the lower coastal frequencies.



If you are a ham generally this means you want the maximum efficiency on 20 meters and hence that would mandate a backstay length of no more than 40 feet to meet the maximum 5/8 length.





I have never found that a high angle radiator that wastes power on high angle lobes to be an efficient antenna even in coastal communications. If you want long distance reach go for a low angle radiator not a high angle radiator and that means no longer than 5/8ths. I am a ham so my backstay is no longer than 41 feet on 14mhz. This is long enough for high efficiency on the lower frequencies with an antenna tuner and where signal levels are strong enough where you dont have to worry about 3db loss since you will be so strong. I want the ability to send an email and communicate with realiability hence my choice.



A piece of wet string laying on the deck is good enough for coastal communications including feeding your lifeline as an antenna. This might seem like overthinking but really there is no such thing as overthinking when it comes to the efficiency of an antenna system and when it comes to designing a communications system for reliability.



I am in the over thinking camp because the laws of physics mandates maximum effiecieny not lazyness and poor aptitude. But hey if this is too much information overload, throw it up and suck it and see. Everything sorta works when it comes to radio, even the worst antenna and ground. Being on top of a saltwater is what saves most sailors from their misinformed decision making.



I did a signal survey over many Sydney to Hobart yacht races. I used a very accurate communications receiver with a S-meter that had a less than 1db accuracy.(dbuv) There was anywhere from 20 to 30 yachts all within 20 nautical miles all with professional HF communications installations. There was an incredible 40db variation from this fleet sample from the weakest to the strongest. And this variation came mainly from poor installation, poor antennas, poor grounds and not propagation variation since they were all in the same zone.. I was using a calibrated EMC antenna. So there you go, if you overthink you can get 40db over the yacht that takes a lazy and casual non technical approach to a technical subject! You can find all this information in the ARRL antenna handbook, buy a copy its a good learning aid for those who are interested.

[Cpt Pat]

Originally Posted by s/v Jedi

With a good automatic antenna tuner you should be able to TX at all frequencies. My smart tuner (sgc works on every radio) does for sure.

That said, I would go down 2 meters from the top so 15m length. The reason is that I know it works well on both the SGC and Icon tuners I have. If you have a different one then you may have different requirements.

I also have an SGC tuner. It'll tune a paperclip at 160 meters (OK, a slight exaggeration). If the OP is using any other tuner, it may not perform as well.

20 meters is the best daytime band, and an important freq. is 14.300 MHz. It is almost continually guarded for marine distress calls and hosts seafarer's nets.

I avoided the issue of antenna 1/2 wave resonance entirely by using a delta loop antenna. More on that here: https://www.eham.net/article/29751

N8QH

[Topspin]

Originally Posted by Cpt Pat

I avoided the issue of antenna 1/2 wave resonance entirely by using a delta loop antenna. More on that here: https://www.eham.net/article/29751

N8QH

Hi Cpt Pat,

unfortunately, I can´t view the picture of your setup in the above link. I understand that the delta loop does not need a ground system. I also understand, that you use a delta loop from bow to stern to masttop.

Would a configuration of 22m/22m/4.5m ( port stern / masttop/ starboard stern) work as well? Probably not that good, because the base length of the triangle is not wide enough, but such a configuration would be easy to realize.



-Richard (VK4WRS)

[Topspin]

OK, I found the other thread for delta loops at this forum. Other sources recommend feeding at an edge of the triangle for favourable polarisation and leaving the upper edge open to keep the tuner happy. I am still not quite sure about the impedance at different feedpoints.....
Maybe an interesting concept.

-Richard

[Cpt Pat]

Originally Posted by Topspin

Hi Cpt Pat,

unfortunately, I can´t view the picture of your setup in the above link. I understand that the delta loop does not need a ground system. I also understand, that you use a delta loop from bow to stern to masttop.

Would a configuration of 22m/22m/4.5m ( port stern / masttop/ starboard stern) work as well? Probably not that good, because the base length of the triangle is not wide enough, but such a configuration would be easy to realize.



-Richard (VK4WRS)

Below is a copy of the drawing. Click on the thumbnail.

The element lengths aren't critical. Achieving resonance isn't a goal. Bigger is better, and your boat is bigger than mine. A delta loop is not as efficient as a resonant antenna, but it also isn't as frequency selective.

In the drawing, I indicate the line that runs through the bilge is "ground." By that term, I mean that is where a connection is made to the boat electrical negative. It's DC ground. There is no RF "ground" per se and no connectivity to the water. A loop doesn't require a ground plane.

The antenna is no more directional than a backstay antenna.

I do recommend a lightning drain path. I attach a 2 sq. foot zinc plate to the backstay chainplate, and trail that plate when needed. It produces no RF effect: I see no change in antenna effectiveness with or without the plate in the water. Don't use copper or bronze if you have an aluminum propeller. It will create a galvanic couple and rapidly corrode the prop. When not selling snake oil, some people have gotten rich selling bronze "dynaplates." By the way, those plates don't behave well if a lightning hit is ever discharged. Attached to the hull, they can blast a hole in the hull. Water can't be compressed, fiberglass can.

I used stainless steel braid for the element running through the bilge after I realized in "version 1.0" of the antenna that seawater dissolves copper braid. Here's a source: http://www.ags.bz/. When I worked as a broadcast transmitter engineer, that's all we used for the tower ground plane radials. Never copper in saline environments. I shake my head when I see someone laying copper wires or mesh inside their hull for a ground plane. If it's ever exposed to salt water, check to see if it hasn't been turned to powder in a few months.

My design is heresy for traditionalists. Fortunately, on CF, they don't burn heretics -- only flame them.

Since you don't have to make any modifications to your rig, I suggest experimenting with a temporary set up. WWV makes a good test beacon at 2.5, 5, 10, 15, and 20 MHz. There are other lower powered beacons listed here: https://www.hfunderground.com/wiki/Radio_propagation_beacon. Use "CW" or USB mode to hear those otherwise unmodulated beacons.

[continuouswave]

Originally Posted by plebian99

...So there you go, if you overthink you can get 40db over the yacht that takes a lazy and casual non technical approach to a technical subject!

Yes, the antenna is the most critical element of the station in most instances, and in the case of end-fed vertical monopoles, the ground or counterpoise is the most critical part of the antenna.

[ka4wja]

My apologies to all, for not being more precise in my words...

I never meant to say (nor imply) that doing due diligence in antenna system design was bad....certainly I 100% believe the opposite!
(anyone that's ever read one of my long-winded ramblings on antennas can attest to that, as well as listened to me ask questions of the inquisitor regarding details of their application, when asked about what is the best antenna....LOL)

What I was trying to say is that for this gentleman and his application, he was "over thinking" this a bit...




And, while I've steered away from controversy here, and won't go on arguing these points...allow me to be even more precise...

Back > 15 years ago, I spend some time in conversation (a few weeks of him and I discussing and modeling) with the late L.B. Cebik, W4RNL (SK), discussing the possibilities (lack of them, actually) of accurate antenna modeling for backstays on sailboats....with all the other rigging, mast, boom, etc.....there were just too many variables to make any of the current models give accurate results....
{fyi, L.B. was a buddy whose work is still used today....heck, I've used some of his papers in some seminars I teach....and sadly we also had elderly/ill family in common...}


So, while I do appreciate the new modeling.....it's not exactly telling us anything we haven't known for decades....
An approx. 40' (40' to 45') backstay antenna is darn close to being the "best overall" solution for most HF sailing applications....


And, fyi....if you have a look at some of L.B.'s papers (the slippery sloper....and the 5/8-wave myth/mystique?), you can quite quickly see that the whole "43' vertical craze" is more marketing hype than reality....(there are high-angle lobes in a 5/8 vertical along with the lower....and that's at best, over so-called "perfect ground".....and of course how the actual radiation angle of slopers isn't as low and narrow as a "vertical", even over sea water....)


Further, fyi....L. B. did latch onto a some interesting occurrences in some of his modeling of backstay antennas....For sloping verticals, particularly ones that are sloped from a conductive support, the higher angles from antenna lengths beyond 0.64lamda (while still present) are not the only lobes (lower ones do exist)...
{I've since moved thru 3 or 4 computer changes....and don't have those model results here with me, or I'd post 'em here.....but, if I can locate them in March, I will....}



Okay....okay...
Now do you all see why I was trying to encourage the average sailor to "not over think" this???

It's not because this isn't important, but rather for the average sailor, the old adage of 40' - 45' long backstay antenna is still the best overall choice....(for those looking at optimizing for the lower HF region, especially wishing to reduce tuner losses for MF and low HF, a longer antenna is good....for those looking to optimize for the upper HF region, a shorter antenna is good...)


And, lest we forget that now-a-days we are using 8mhz as a long-range band (as well as 40m ham band), where just 4 - 5 years ago, these were "regional" bands (and daytime for local comms, out a few hundred miles), but now these are those long-range bands that 12mhz, 14mhz, and 16mhz had been....
Heck, I get AMSA BOM maritime weather on 8176khz now, all the time....when just a few years ago I used get great copy on 12362 and 12365, and rarely heard 8176....and this is from the same dock in Florida, approx 9000 - 11,000 miles away!



Oh, and not to split hairs here, but it's not a "5/8's wave" (0.625 lamda) that is the critical point, but rather 0.64 lamda.....above which point you lose the low angle lobes....
You see, there are things that the average sailor just doesn't need to worry about...


Gosh, can we now just let derfy use his radio?

Fair winds to all.

John

[Topspin]

Hi all,

I know, I should set up another thread... I am still thinking about alternatives to the backstay antenna. Like probably many other sailors, I abhor the idea of cutting my backstay and putting in insulators which cost almost 1 grand. I also understand, that installing a proper HF-ground may be a serious project, even when using the cheap 5$ ground :-)

So the idea of using an alternative backstay is tempting, especially when there is a possibility of not having to deal with the counterpoise.

As I am far from designing my own antenna, I would like to ask the more knowledgeable OMs here about an idea that came to me when I considered two alternative backstay antennas and joining them into a delta loop using the automatic antenna tuner. Have a look at the picture, viewn from the stern, the lower attach points are the port/starboard sides of the solar arch). The tuner is placed below the solar panels.
Beam width is 4.5m, mast height is around 20m. Such an antenna would cost less then 50$ (wire, 2 small pulleys, some thin rope) and would be easily installable in less than 1 day and only one trip to the mast top. It could possibly be easily converted into an inverted V......

Any ideas about that ?



-Richard (VK4WRS)

[ka4wja]

Richard,
{I'm not sure if you're based in Cairns, but fyi I will be in Cairns (actually staying in Palm Cove) for 5 days in the middle of Feb. }



1) I understand your questions here (yes, you're asking many questions in one).



2) And, yes, I agree you should start your own thread
(which will attract much opinion, after all, you'd be basically discussing re-inventing the wheel....and probably give me a headache reading....LOL....so, chances are that I'll steer clear of it....)




3) For clarification...you're floating on one of the best antenna grounds there is, the sea water....and connecting to that is not difficult, nor expensive.....so, avoiding a monopole antenna because of a perceived complexity in designing/building an antenna ground, seems odd to me....

And, fyi, any single-ended antenna (monopole) whether it holds up your mast, or is simply an extra wire supported by the mast, or a whip, etc....any of these require an antenna ground (sometimes called a counterpoise)....but balanced antennas (such as loops of sufficient size, dipoles, etc.) of course do not require any antenna ground at all...




4) But, to be clear, I think you are going about this an entirely opposite way than what is normal "good antenna engineering".....sorry my friend, but in my opinion/experience this is fairly backwards way to designing / looking for antennas...

Bottom line.....the way you design an antenna system is to determine your specific application, and design an antenna that meets those design criteria....and one that of course fits in the space you have available as well as one that you can mount/install securely...

But, it seems that you're dreaming up antenna ideas that are inexpensive and then see if someone can tell you how well they'd work??

If you're looking to save money, then make your own antenna without expensive insulators, etc....and one that some have used is just to load-up the entire rig!
You simply feed a chainplate with a piece of GTO-15 wire from the tuner, and connect a piece of copper strapping from the tuner ground lug to the sea water (underwater grounding plate, Dynaplate, or a thru-hull), and you're done!
How well will it work???
Well, nobody knows.....'cuz this is VERY boat specific....but it's cheap and easy....so, if that's your goal, go-for-it!

But, if you want an antenna that suits a particular application, then design the antenna for that application.....yes, it may cost some $$$ that you haven't built into your budget, but certainly less than what most spend on a new smart phone every year or two.....so, the "cost" is relative...




5) As for your specific idea....a tall and narrow loop (delta loop or any shape, that is tall/narrow or short/wide), generally present a fairly low-impedance and poor wideband performance, but at resonance present an easy match to low-impedance feeders (coax)....

Sorry, I don't have the time to model this.....you're on your own there...

But, fyi, I designed/built a similar antenna (albeit 110' wide and 20' tall loop) for 75m DX work, side-fed, for vertical polarization....and while it did work (and was easy to adjust to low-VSWR with 50-ohm feed), it was a single band antenna.....and when attempting to use (with remote tuner) on multiple bands, it was a rather poor performer compared to a simple dipole, on just about any skywave path (many tests at ranges of a few hundred miles, ~ 1500 miles, and also 4000-5000 mile paths), and to be honest was a total dog of an antenna on any band other than 75m!

So, without modeling it on a wide range of freqs/bands, I'm going to make an educated guess that you'd not be happy with its performance....

And, btw, save the effort altogether if you're considering this tall/narrow design as an inverted-V (whether end-fed or center-fed), as you'd be better off using just one wire (monopole).....which is what we've all been talking about (a "backstay antenna")....




6) BTW, I'm curious here....
Can someone please tell me where are all these sailors that abhor cutting SS wire?? (I see some posting on-line about this, but I've not seen this in the real-world)

I've been doing this for decades, and have seen my share of dismasting results, and never seen a rigging insulator failure.....but have seen a LOT of swage/wire failures (from crevice corrosion and just plain old rust)...

If well maintained, a piece of rigging wire is unlikely to fail, except for at a fitting / swage, etc....so, yes, I see that if you add more fittings you are technically adding another potential point of failure, but proper inspection/maintenance is needed for all rigging and rigging fittings, so what is it that some sailors are concerned about?

Yes, I understand the costs of the insulators and labor costs of a rigger....yep, these can be budget-busters, but other than costs, I haven't seen other legit reasons to be concerned....



Okay there's more, but that's about all I can muster tonight....

Why not just start your own thread?

Fair winds.

John

[Topspin]

Originally Posted by ka4wja

Richard,
{I'm not sure if you're based in Cairns, but fyi I will be in Cairns (actually staying in Palm Cove) for 5 days in the middle of Feb. }

Hello John,

Palm Cove is a beautiful place to be (I just live 2 beaches to the south). I hope the weather will bring you lower temperatures and lower humidity (right now it is almost anbearable without aircon). If you need information or help, please drop me a PM.

3) For clarification...you're floating on one of the best antenna grounds there is, the sea water....and connecting to that is not difficult, nor expensive.....so, avoiding a monopole antenna because of a perceived complexity in designing/building an antenna ground, seems odd to me....

And, fyi, any single-ended antenna (monopole) whether it holds up your mast, or is simply an extra wire supported by the mast, or a whip, etc....any of these require an antenna ground (sometimes called a counterpoise)....but balanced antennas (such as loops of sufficient size, dipoles, etc.) of course do not require any antenna ground at all...


4) But, to be clear, I think you are going about this an entirely opposite way than what is normal "good antenna engineering".....sorry my friend, but in my opinion/experience this is fairly backwards way to designing / looking for antennas...

Bottom line.....the way you design an antenna system is to determine your specific application, and design an antenna that meets those design criteria....and one that of course fits in the space you have available as well as one that you can mount/install securely...

But, it seems that you're dreaming up antenna ideas that are inexpensive and then see if someone can tell you how well they'd work??

If you're looking to save money, then make your own antenna without expensive insulators, etc....and one that some have used is just to load-up the entire rig!
You simply feed a chainplate with a piece of GTO-15 wire from the tuner, and connect a piece of copper strapping from the tuner ground lug to the sea water (underwater grounding plate, Dynaplate, or a thru-hull), and you're done!
How well will it work???
Well, nobody knows.....'cuz this is VERY boat specific....but it's cheap and easy....so, if that's your goal, go-for-it!

I must admit, that my DX times are 30 years ago and I have worked with a 4-band vertical and a W3DZZ pretty well. So please forgive me, when I try to think things through in terms of limited experience and just a little bit of knowledge. I understand, that a forum like this is a good way to get into contact with more knowlegeable people.

I personally do not understand why I should cut my backstay and use expensive isolators, when an alternative backstay antenna will do it.

The counterpoise is a bigger problem. I do not want to drill too many holes into a hull, so I don´t like the idea of a dynaplate. In terms of using a through hull, I think that is a smart idea and I keep that in mind. The other option of using copper foil to create a capacitive bond is smart, but I have seen a friend doing that with a very high amount of work (but admittedly good result). So my idea was to look at options to avoid the counterpoise problem, which led to the idea of using a type of dipole or the delta loop.

And what is wrong in reducing the cost ?

5) As for your specific idea....a tall and narrow loop (delta loop or any shape, that is tall/narrow or short/wide), generally present a fairly low-impedance and poor wideband performance, but at resonance present an easy match to low-impedance feeders (coax)....

Sorry, I don't have the time to model this.....you're on your own there...

But, fyi, I designed/built a similar antenna (albeit 110' wide and 20' tall loop) for 75m DX work, side-fed, for vertical polarization....and while it did work (and was easy to adjust to low-VSWR with 50-ohm feed), it was a single band antenna.....and when attempting to use (with remote tuner) on multiple bands, it was a rather poor performer compared to a simple dipole, on just about any skywave path (many tests at ranges of a few hundred miles, ~ 1500 miles, and also 4000-5000 mile paths), and to be honest was a total dog of an antenna on any band other than 75m!

So, without modeling it on a wide range of freqs/bands, I'm going to make an educated guess that you'd not be happy with its performance....

Thank you, that is exactly the information I was after. Nevertheless, I will set up a second alternative backstay just to have some options for experiments and otherwise rely on a radial type counterpoise or just a wire dropped into the water.....

6) BTW, I'm curious here....
Can someone please tell me where are all these sailors that abhor cutting SS wire?? (I see some posting on-line about this, but I've not seen this in the real-world)

I've been doing this for decades, and have seen my share of dismasting results, and never seen a rigging insulator failure.....but have seen a LOT of swage/wire failures (from crevice corrosion and just plain old rust)...

Maybe it is just a fight between reason and emotion? I know that backstay insulators are pretty safe, but cutting the thing hurts.......

Thanks a lot.

-Richard

[plebian99]

Any altternative to the normal backstay will need to be considered very carefully. Its unfortunate that many hams think that the only objective in antenna design is to get an antenna up regardless of how efficiently it radiates. If you consider what drives and delivers a signal to the far end of the world then you quickly run out of options if you want an effective signal. Sure anybody can come with a contraption or sneak a wire around the boat and call it a "mydesign" created antenna. But is it any good.


1. The number 1 requirement for any antenna is to radiate your signal at the apporiate angle of radiation. If you dont consider angle of radiation or takeoff angle you really just wasting your time.

2. Since most long distance propagation paths rely on takeoff angles between 1 and 15 and very feew long distance paths rely on high angles, any antenna that you create should focus the majority of your power in this 1 to 15 degree range.
3. On a yacht the only antenna that will achieve these desirable take off angles over saltwater is a vertical antenna, or some antenna that has dominant vertical polarisation. The only way you get can these takeoff with a horizontally polarised antennas is mounting very high 0.75 lamda or higher.
4. I really dont know why you fear cutting yoru backstay so much when they all certified structural rigging components that have more than enough safety margin?
5. The other issue you forgetting about is that maintaining the antenna pattern on all frequencies is a tough ask. The most efficient antenna for maintaining the ideal pattern on all frequencies is a vertical antenna fed with a automatic antenna tuner since the losses are minimal. If you compare matching losses with the losses of a antenna producing a bad radiation pattern you are way ahead with the matched antenna tuner losses. You can look at any Navy, Military or commercial ocean going vessels and they all use vertical antennas fed with antenna tuners between 25 and 35ft long. Even commercial aircraft use a short tuned tail vertical shunt antenna with poor efficiency and a high efficiency tuner because they can mitigate losses because they are so high above lossy ground. We should take this lesson as sailors and accept the fact that seawater is a low loss ground use antennas that best work over this low loss ground.

6. If you have a lot of time on your hands and are a ham there is no harm in learning and experimenting with odd bits of wire "just to get a wire up" but dont confuse effectiveness with mindless endeavors. Getting a antenna modelling program will save you lot of effort.
7. In an amergency you can feed your top lifeline as an NVIS antenna and even this low antenna that is nearly scraping the deck will enable coastal communication. NVIS signals are very strong and I would not worry about crap antennas on short range coastal communications circuits.


8. I would put all my endeavors into short loaded vertical or antenna tuner matched vertical antennas. Even if you want to feed your whole mast and rig you will need some form of isolation to break various elements to perform. Feeding the rig as a loaded vertical would work very well on the low bands. However you will have to then float your rig and then expose yourself to an unground mast with the dangers of that!


9. That stretched delta loop antenna can be simply feed through a variable capacitor against ground. Again it will work just like a fat vertical, but vertical polarisation it will be. if you feed it as a random length loop you will get lucky on some bands and unlucky on a lot of bands. A lot of bother for a poor return.


10. Get the backstay insulators, antenna tuner and use a 41 ft vertical and call it quits.


11. I worked Jeanne Socrates VE0SJ from every square inch of the globe using her backstay antenna and autontuner. It was like a total circumnavigation test of communication paths on 7 and 14 mhz something that could be repeated on the marine frequencies. There was never a time I could not work her only because she was skilled ham operator, enjoyed ham radio, was on all the time, and had a good installation. No magic, voodoo ground bought in a packet or other rubbish to make others rich who exploit ignorant people(kiss ground)Sometimes as hams self obsessed with tinkering with grounds and antennas when the most effective solution has already been determined for you by propagation and the many sailors who have achieved success. Why reinvent wheel?


12. If you do want to make the backstay more efficient put a insulator right in the center and load it with an inductor and switch this inductor on various frequencies against ground. Even removing the inductor and using half a backstay on the higher frequencies produces even better result. The same thing is dont on battle ships 22 to 25 foot verticals for the higher frequencies, and the 35ft vertical for low frequency communication and sometimes they use 1kw or 5kw of power. Listen on the aircraft frequencies of 5mhz and listen how well low efficiency vertical antennas work if you have a proper ground much like that of seawater. Sailors are looking for voodoo and magic when none is needed for HF communications when you are sitting on seawater and have a marvelous antenna that will have decent pattern on all frequencies between 1 and 15mhz. If you do want better efficiency from 15 to 30mhz a shorter vertical would be a good idead, but considering where we are in the sunspot cycle I would not bother. You cannot beat a 5/8 wave antenna or 40ft vertical antenna on 14 mhz nor can you design an antenna with a better pattern or efficiency for long distance propagation on a yacht sitting over saltwater. If you examine a performance ham station based on land, the formula will be exactly the same, verticals, phased verticals over miles of radials. We fortunate we dont have to invest our retirement money into copper wire over seawater! But if you do have money to waste you can buy the wires in the hose pipe kiss ground!

[j.g.evans]

I have done some simulations of a very complex model of using a backstay as an antenna, insulated and not. All simulations show that the signals are coupled into everything and re-radiated. The radiation patterns and antenna impedance are good at some frequencies and ugly at others with and without a top insulator. I chose not to cut my rod rigging and put in an isolator. I was able to use Winlink on 4-22 MHz with an Icom 706 and an AT 120 tuner. Another reader commented that the ground is important too. It is hard to achieve anything approaching an ideal or good ground. In one boat I used the keel and in another I used CU sheathing inside the hull to capacitavely couple to the water. Both worked; but, were far from an ideal ground.
Just do something and it will surprise you.

[Steve DAntonio]

Originally Posted by Stewie12

I used a centre fed dipole attached to the back stay. It was great.

I to have had good results with the KISS product, btw.

One can agonize over these length calculations too much IMO. I would avoid the 23 foot minimum, then make the backstay antenna section as long as practical, installing the lower insulator above head height to prevent someone being shocked if they were holding the antenna while someone else was transmitting. Another contributor noted, rightly, to include the GTO cable length as part of your calculation and remember it is a transmitting part of the antenna, so avoid running it, or the tuner, under a bunk for instance.

You might find this article helpful in the set up. Setting up single sideband - Ocean Navigator - January/February 2003