Marine HF - switchable, distinct, short & long range antennae

[klewless]

Hello, Klewless here. Longtime lurker, first-time poster.

Although a licensed and experienced user of different bands and gear for professional (CCG 60 t limited Master) and volunteer (longtime 'lifeboat' crewman) applications, coming to terms with a personal, recreational Marine HF setup is the most daunting challenge of my comms experience.

Let me thank anyone who reads this ahead of time: I greatly appreciate you and the forum. Note also, that criticisms are welcome.

Sooo... I'm looking at spending the equivalent of one year at a technical college on SSB gear. Icom m803, or possibly the GMDSS vers., w/Tuner, Pactor 4, prof. Dynaplate installation, etc.

I figured that before asking these questions in person and looking like a moron to my installer - 'a someone' who speaks regularly with my local Transport Canada Examiner - I'd instead chance looking like one here and just hope and pray it never gets back to my local overlords.

Alright, I want to ask about the possibility of having two antennae for my HF. One for short-range, the other, for long-range. I anticipate making use of both and given the investment I would like to develop as much value as possible from the system. Anticipated areas of travel include both polar regions, Pacific N, E, S, W. Perhaps something like a backstay antenna or a vertical antenna strung up between masts on a ketch, and a horizontal twin dipole.

Only one antennae at a time would be activated so it seems to me they could not interfere with each other. I assume the switch would occur post-tuner, and I'm curious what losses such a switch might incur if this installation in the end does have potential. From my technically ignorant perspective, this switch seems the likely flaw, but at the same time, I can't imagine something hasn't been devised by this point.

Concerning earth/grounding: It doesn't seem feasible to deploy dual groundings on a 50ft sailing yacht, but so long as the system switches completely, physically from the second antenna, it seems to me one ground system ought to suffice. I realize that different ground systems also predictably offer advantages for longer and shorter wave comms, but having two groundings on the boat does not seem feasible. Maybe I'm wrong on that.

Thanks for your time and interest.

[wholybee]

The simple answer is that for short range you use VHF, and VHF has its own antenna.

But, regarding the SSB. You can have more than one antenna. They can share the same ground/counterpoise if the type of antennas dictated that. You could either switch between antennas on the output side of the tuner, or use a coax switch at the radio output and use 2 tuners. I would suggest that latter, since the 2 antennas would probably be very different, and one might not even use a tuner, or a completely different type of tuner.

That said, a sailboat is a unique situation. There is basically only one type of antenna you should use, a random length wire antenna. Usually this is the backstay, sometimes it is a long fiberglass whip. The design and length of this antenna would not change for the intended range. So, really no reason to have a long range and short range antenna.

You _could_ conceivably build an antenna specific for ground wave communication, or specific take off angles to achieve certain characteristics for distance. But such antennas don't translate to an installation on a boat very well. And aren't really necessary when VHF is readily available.

[Jammer]

Originally Posted by klewless

Hello, Klewless here. Longtime lurker, first-time poster.

Hi. Hope you have a clew, or at least hope that your sail does

Alright, I want to ask about the possibility of having two antennae for my HF. One for short-range, the other, for long-range. I anticipate making use of both and given the investment I would like to develop as much value as possible from the system.

Sure. Let's explore that together.


Generally, with HF on boats, people use backstay antennas because the backstay is already there, so there's no need to add something that creates windage, cost, etc., or especially to have something that has to be deployed when in use and then put away. The backstay antenna has the advantage that, except in the event of a loss of the rig, it is ready to use in any emergency and doesn't have to be deployed or set up.

Depending on who you're talking to and what you consider to be "short" range vs. "long" range, there may be better alternatives.

In reality, most short/mid-range HF from one boat to another boat is going to use the 8 MHz band, because it almost always works for that, and unlike the 40 meter ham band it isn't especially crowded. Most of the nets that still operate are in this band also (but not all). So you could build something specifically for that band, maybe a nice basic center-fed dipole sloper, with a couple of small loading coils if you need them to get the length down to what you can manage on your boat.


For longer range comms when the sunspot conditions allow use of higher frequencies, antennas are physically smaller and you would have more choices.

Only one antennae at a time would be activated so it seems to me they could not interfere with each other. I assume the switch would occur post-tuner, and I'm curious what losses such a switch might incur if this installation in the end does have potential. From my technically ignorant perspective, this switch seems the likely flaw, but at the same time, I can't imagine something hasn't been devised by this point.

Insertion losses for switches are typically not signficiant. You can switch either post-tuner or pre-tuner. Some antenna designs do not benefit from an antenna tuner for example so you might only use the tuner for one (or some) of your antennas. Coaxial switches are available from places like Gigaparts or The Antenna Farm. For post-tuner switching, a simple knife switch works best.

Concerning earth/grounding: It doesn't seem feasible to deploy dual groundings on a 50ft sailing yacht, but so long as the system switches completely, physically from the second antenna, it seems to me one ground system ought to suffice. I realize that different ground systems also predictably offer advantages for longer and shorter wave comms, but having two groundings on the boat does not seem feasible. Maybe I'm wrong on that.

Typically, band-specific antennas don't rely on grounding. A major drawback of the backstay antennas in widespread use is that they depend on a good seawater ground for best results.

You may want to think through your overall communications strategy given that marine HF is currently in decline. Shipcom and similar voice-based shore stations are gone now and do not appear likely to return, and the amateur radio community has become hostile towards marine uses. Meanwhile alternatives like Starlink, Iridium, Iridium Certus, and various lower-cost satellite communication devices (InReach among many others) have become more compelling than HF on grounds of overall cost and performance.

[Jim Cate]

^^^^^

and the amateur radio community has become hostile towards marine uses.

I've been operating as a maritime mobile for some 38 years now and have never experienced a negative reaction from the ham world. Could you elaborate a bit on your statement, please.

Jim N9gft/mm VK4gft/mm

[Jammer]

Of course, Jim. Perhaps I should have been more specific. As you may remember, I've been licensed since the late 1980s but only sporadically active.

In the USA, amateur radio, particularly HF, has become more contest-centric over the years and has become increasingly opposed to what we could call "utility" uses, that is, any sort of communications that carries information of any utility or value. This has been done based on an increasingly broad reading of the FCC limitation on using amateur radio for commercial purposes. Since substantially all human activity has some sort of economic nexus it becomes impossible to engage in substantive communications. So it becomes impossible to discuss slip arrangements, parts, repairs, anything other than weather. Maybe not even that if you're paying someone to talk to you about the weather.

This is in contrast to the more traditional reading of the rules, from the 1950s, which was that you couldn't use amateur radio in furtherance of your own trade or business but that more or less anything up to that point was fine. So if you ran a concrete company you had to use the commercial frequencies for dispatch. But if you were an individual in a remote area and were trying to coordinate a concrete delivery you could use amateur frequencies to do it and back then no one cared.

Where this has been most problematic is in the relatively recent loss of the ability to use winlink for email, for winlink users with USA call signs. Even for non-USA callsign holders, there have been reports of people having their callsign banned from winlink after a station operator reads through their mail and observes traffic that the operator considers objectionable due to its commercial nature.

There was one recent story of someone trying to get their autopilot to work, emailing the manufacturer, and having comms cut off while they were on passage somewhere by some busybody winlink operator who decided it was too commercial.

Probably things are better in Oz.

[klewless]

Yeah, it was take-off angles that I was thinking of, primarily. Thanks for reply.

I'm on Canadian Pac. coast, which is essentially wilderness, but, for example, I know a lot of trawler cptns, their TODs, MMSI's and targeted offshore grounds, who are well out of VHF range but will respond to hF. In fact, it can be harder to get off the radio with those guys, than on. ha. Lots of good traffic and met info to be gleaned there.

Plus, in an emergency at sea, making sure that the people 24-48hr away from me can hear me seems entirely practical.

Given some of the possible conditions and coastal geography, I thought having two antennae would at very least provide me a practical education on propagation.

If I attempted sat-coms, guaranteed the cheapskate owner will one day knock on my door with an inmarsat bill scrunched up in his chubby fingers demanding payment. Ask me how I know. lolz.

The difference between going someplace and knowing nothing, as compared to even just knowing one thing, is remarkable. Esp. boats that are 24-36hrs travel distance from you, that's the sweet spot, and VHF just doesn't cut it.

With nothing you can do, well, nothing. With something you can often infer enough to build out a whole operation. Every plan seemingly, 'goes to hell when contact with the adversary is made', but Eisenhauer still knew how important having a plan was, regardless.

Thanks for directing me to consider the tuner more thoroughly.

[Jammer]

Originally Posted by klewless

Yeah, it was take-off angles that I was thinking of, primarily. Thanks for reply.

Generally, control of the take-off angle would be a luxurious thing to aspire for when it comes to antennas on boats.


HF on boats works because a boat on passage can be made free of man-made electrical noise to an extent that few land-based stations can achieve. Therefore HF comms can take place even though antenna performance is poor, as it must be, because it is not possible to have a tri-band half-wave yagi 80 feet above the ocean on a rotator, and it is not possible to have an 80 meter NVIS antenna because there's no place to put it.

[S/V Illusion]

Originally Posted by klewless

Yeah, it was take-off angles that I was thinking of, primarily. Thanks for reply.

A non-issue. The take-off angle is a function more of elevation than antenna type. And all verticals have an inherently low major lobe angle.

Given some of the possible conditions and coastal geography, I thought having two antennae would at very least provide me a practical education on propagation.

Antennas don’t affect or change propagation. If you really want to study propagation, using multiple antennas serves only to confuse the observed effects.