HF Antenna on Light Aircraft

Maverick

Maverick

Line Up and Wait
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Apr 2, 2005
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636
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St. Clair Shores, MI
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Display name:
Jean
Has anyone for any reason used an HF radio in a light aircraft and if so what was used for the antenna. I've had an amateur radio license for 30 years now and a friend of mine and I have had this idea of operating amateur radio field day from an aircraft. Of course this would require an HF antenna that could be used with an antenna tuner on the 20, 40 and possibly 80 meter amateur bands. I certainly don't want to do anything that would be in violation of regs or compromise the aircraft.

I spoke with someone at the FAA flight standards booth at Oshkosh once and he told me that antenna couplers have been used that actually use the airframe as the antenna. i have no idea where I would find one that is certified for use in such a manner. All my internet searches have come up empty handed.

Anyone have any ideas?

Jean
 
Sometimes those crossing the Atlantic use HF, maybe one of those ferry outfits or suppliers can help?
 
That was my thought too and at least one of the avionics shops sells a radio for that purpose. The radio is one that is made for amateur radio operators but they have a disclaimer that it is not FAA approved. Still it is unclear what they are recommending for an antenna. I suppose I should give them a call and ask but if it's not an approved installation I want to stay away from it.

Jean
 
Well, last time I used HF in an aircraft (sorry, not light aircraft) I used to just hit the "OUT" button to reel out about a quarter-mile of trailing wire antenna behind us...used to have pretty decent comms at 25,000 over the open ocean with that setup! :)
 
I've long wondered what the attraction is to combine airplanes and amateur radio.

Sure, you can get really high, but your antenna can't have much gain, right?

However, seeing the article above...it makes me wonder if a 2m phone patch might be a really cheap way to have a phone in your airplane. Has anybody done it successfully, and if so, what are the pros/cons?

Thanks,
Bob
WA4YZA
 
RobertGerace said:
I've long wondered what the attraction is to combine airplanes and amateur radio.

Sure, you can get really high, but your antenna can't have much gain, right?

However, seeing the article above...it makes me wonder if a 2m phone patch might be a really cheap way to have a phone in your airplane. Has anybody done it successfully, and if so, what are the pros/cons?

Thanks,
Bob
WA4YZA
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Bob, you've read my mind here; I've often wondered about 2m in aircraft, and have seen non-av VHF rigs in panels on airplanes before. I kind of think it would be better if you could have connectors available to "plumb" the 2m into the audio panel on a temporary basis, rather than having to get a field approval of a permanent installation.

Then again, traffic reporters and S&R folks use non-av radios all the time, so it must not be *that* tough to do.

Next question: I see most modern 2m radios have the DTMF pad in the mic; how to handle that with headset / audio panel hookup?
 
sshekels said:
Welcome from Ka7GXP! If you are interested check out:

http://www.omen.com/f/avradio.html

Chuck has been doing it for a long time, and has been REALLY nice EVERY time I emailed him with an odd question.

S.
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That looks really interesting. I just forwarded that link to my friend as well.

I have two antennas that I bought to cover the 2 meter and 70 cm bands. I need to get those mounted on the aircraft yet.

Thanks,

Jean
N8CTN
 
RobertGerace said:
I've long wondered what the attraction is to combine airplanes and amateur radio.

Sure, you can get really high, but your antenna can't have much gain, right?

However, seeing the article above...it makes me wonder if a 2m phone patch might be a really cheap way to have a phone in your airplane. Has anybody done it successfully, and if so, what are the pros/cons?

Thanks,
Bob
WA4YZA
Click to expand...

My interest is more in the line of doing something different. I'm not really in it to try to win any contest. Besides, field day is a 24 hour event. No way will I be flying for 24 hours. My thoughts are to fly a few hours, land and have the hundred dollar hamburger and then go fly for a few more hours.

I've operated 2 meters and 70 cm from the air in the past. A friend of mine and I have also broadcast live TV from an airplane in conjunction with a Civil Air Patrol disaster relief mission on a few occasions. We really impressed the local emergency services officials with one of those missions. We did this long before the TV stations got their fancy helicopters outfitted with TV down links. But I've never done HF fro the air. It's just another thing to do that I haven't done before.

Thanks,
Jean
N8CTN
 
Glad it was a help Jean!

At another web site (to be un-named) I was flamed about HF in an aircraft. Go figure. Part of pilot training is learning to handle distractions - Most of the flames were about "how can you EVEN THINK of using ham radio when you are BUSY flying?" Hmm, maybe don't use it when your workload is too high? LOL

Anyway, I would guess HF would be a dissapointment in GA. Too small of an antenna, and height does not make all that much difference. (I'm sure Lance would have some good insight here!) VHF on the other hand is VERY COOL. I went up for a scout day on the air, and climbed as much as was reasonable in the 'hawk - Talk about lots of folks thinking that was cool! I had a great time, as did the kids. Pilot non-hams don't get the attraction, even though it's very similar to Young Eagles. Go figure.

Anyway, have fun! If I can be of help, let me know! Maybe we could say hi on HF sometime?!?! (or a air-to-air QSO?) (edited after your last post - Lets try an HF air-to-air sometime!)

73s,

Scott
KA7GXP
 
gkainz said:
Well, last time I used HF in an aircraft (sorry, not light aircraft) I used to just hit the "OUT" button to reel out about a quarter-mile of trailing wire antenna behind us...used to have pretty decent comms at 25,000 over the open ocean with that setup! :)
Click to expand...

I worked with someone in the past who was in communications in the Navy. He told me about the C130 h was a crew member on and the big reel of cable they would reel out for a trailing wire antenna. Trouble is no one makes a trailing wire system for a Cessna Cardinal. :(

Jean
N8CTN
 
sshekels said:
Glad it was a help Jean!

Anyway, have fun! If I can be of help, let me know! Maybe we could say hi on HF sometime?!?! (or a air-to-air QSO?) (edited after your last post - Lets try an HF air-to-air sometime!)

73s,

Scott
KA7GXP
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I'm rarely ever on HF. I upgraded my ticket to Extra just to do it almost never get on those bands. I guess I get more out of the challenge than anything. My HF antenna at home is a G5RV that a friend put up for me. I've used it so little that I can't even tell you how well it works.

Jean
N8CTN
 
I inspect and issue Special Airworthiness Certificates for aircraft being exported. Part of the requirement for over weight over water is to have a HF or some other device like a sat com. It very simple to install 0.051 safety wire works very good. The wire is ran from the top of the fuselage, to the tail, to a wing tip. To install follow AC 43.13-2A chapter 3 procedures.

Our local avionic shops carries all the hardware to attach them.

Stache
 
Maverick said:
I worked with someone in the past who was in communications in the Navy. He told me about the C130 h was a crew member on and the big reel of cable they would reel out for a trailing wire antenna. Trouble is no one makes a trailing wire system for a Cessna Cardinal. :(

Jean
N8CTN
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Hmmmm, one handheld or portable HF radio, salt water fishing rod and reel loaded with metal line... poke the end of the rod out the window.... no STC required!!! only kidding, of course! :rofl:
 
I've worked a couple of guys that identified as aeronautical mobile. I think one of them was using an old ADF sense antenna that was fed from an antenna tuner.

As for 2 meters/autopatch, I see no reason it won't work. The problem will be bringing up multiple repeaters and the possibility of flying out of range before the call is finished. A regular com antenna may be close enough to work for 2 m (I might have to hook the handheld up to my extra antenna one of these days).
 
You can get an aircraft antenna tuned for 2m VHF. Also, you can use just about anything for HF with the right antenna tuner. An automatic tuner might work well for aircraft use.

2m works well from the air, no problem with multiple repeaters or flying out of range.. It works much better than a cell phone.

KD7TBK
 
ErikU said:
You can get an aircraft antenna tuned for 2m VHF. Also, you can use just about anything for HF with the right antenna tuner. An automatic tuner might work well for aircraft use.

2m works well from the air, no problem with multiple repeaters or flying out of range.. It works much better than a cell phone.

KD7TBK
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Erik,

Please forgive anything stupid I'm about to write. I have not used my Amateur license in over 20 years. However, I bought some nostalgic equipment (Heathkit) for HF and a Kenwood 2m rig off of Ebay and I'm slowly working my way back.

I'm wondering...as I'm flying along over some state (pick one), and I need to make a phone call...

1) How do I find a frequency?
2) Are many of the repeaters still private (you need to be a member)
3) How did you interface your a/c power to a 2m rig...or are you using a handheld?
4) Same question with antenna unless you are using a handheld.


Thanks!
 
Stache said:
I inspect and issue Special Airworthiness Certificates for aircraft being exported. Part of the requirement for over weight over water is to have a HF or some other device like a sat com. It very simple to install 0.051 safety wire works very good. The wire is ran from the top of the fuselage, to the tail, to a wing tip. To install follow AC 43.13-2A chapter 3 procedures.

Our local avionic shops carries all the hardware to attach them.

Stache
Click to expand...

Got it !

Thanks,

Jeannie
 
We've got a spare VHF antenna on the club's Arrow, so I figured I'd check it out for an aircraft band hand held and 2m. My MFJ antenna analyzer indicated that the best thing to do with that antenna was remove it from the plane and eliminate the drag. VSWR was too high at any frequency. Oh well.

And, glad to see someone beat me to Chuck's web site for information on HF in the plane. His writeup on what he did in his C-182 is great.

We'll have to see about setting up an HF net for pilot/hams some time...

73

N6TPT
 
sshekels said:
Glad it was a help Jean!

At another web site (to be un-named) I was flamed about HF in an aircraft. Go figure. Part of pilot training is learning to handle distractions - Most of the flames were about "how can you EVEN THINK of using ham radio when you are BUSY flying?" Hmm, maybe don't use it when your workload is too high? LOL


Scott
KA7GXP
Click to expand...

Well I certainly wouldn't be operating Amateur Radio while flying single pilot IFR into the Chicago area but loitering over northern parts of Michigan's lower peninsula on a nice day is a whole different thing.

Thanks again,

Jeannie
N8CTN
 
So maybe I should not have been having a QSO coming into Memphis? LOL

Kinda my thought too - Not too many scary things to watch out for over the flat lands of Northern MN! :)
 
wsuffa said:
I've worked a couple of guys that identified as aeronautical mobile. I think one of them was using an old ADF sense antenna that was fed from an antenna tuner.
Click to expand...

The choices for HF are going to be a trailing wire or something like the old ADF sense antenna (wire from nose to tail). Neither one will work without matching and in general, the longer the wire the better. Conventional methods for artificially increasing the electrical length of an antenna for HF (center or top loading) just aren't practical for airborne use AFaIK.

One other thought, antenna height isn't generally much of a factor on HF as long as the top of the antenna is at least a quarter wave above the ground so I wouldn't expect much improvement in coverage with altitude. Working VHF (2M and shorter wavelengths) which is primarily line of sight could give you astounding reach from high altitude without skip, so you might be able to set some kind of record with that.

Also remember that with an unbalanced antenna like the HF longwire the airframe will be radiating half the transmitted power so I'd be carefull about running anything above 10-20 watts without carefully bonding everything together on the airframe. You could create local hot spots thermally and electrically. Arcing across mechanical structures could be bad for the airframe, and you probably don't want to receive an electrical shock when you touch something on the panel. You will essentially be "inside" the antenna.
 
lancefisher said:
The choices for HF are going to be a trailing wire or something like the old ADF sense antenna (wire from nose to tail). Neither one will work without matching and in general, the longer the wire the better. Conventional methods for artificially increasing the electrical length of an antenna for HF (center or top loading) just aren't practical for airborne use AFaIK.
Click to expand...

You can center load if you install a center load in the long wire (whether old ADF sense or trailing wire). As you note below, the issue is one of a good ground. Loading really does nothing for radiation efficiency of the antenna - that is fully defined by the radiational length/area of the antenna - loading is simply there to get a good match to the transmitter. A good match to the transmitter is important because maximum power transfer happens within the final amplifier only when it is matched 1:1.

One other thought, antenna height isn't generally much of a factor on HF as long as the top of the antenna is at least a quarter wave above the ground so I wouldn't expect much improvement in coverage with altitude. Working VHF (2M and shorter wavelengths) which is primarily line of sight could give you astounding reach from high altitude without skip, so you might be able to set some kind of record with that.
Click to expand...

Antenna height at HF is only a factor if you can create a lower angle to the horizon, thereby allowing further distance to skip.... which is why directional antennas on the ground tend to compress the signal towards the horizon. Or if you are high enough that you get fresnel-zone clearance, turning your HF communication into line-of-sight.

Shorter antennas tend to be much more omnidirectional, meaning more energy goes upward where it is wasted. BTW, the quarter-wave above ground is immaterial... remember that you're forming an artificial ground with the aircraft body.

Also remember that with an unbalanced antenna like the HF longwire the airframe will be radiating half the transmitted power so I'd be carefull about running anything above 10-20 watts without carefully bonding everything together on the airframe. You could create local hot spots thermally and electrically. Arcing across mechanical structures could be bad for the airframe, and you probably don't want to receive an electrical shock when you touch something on the panel. You will essentially be "inside" the antenna.
Click to expand...

Beg to differ. Because the airframe acts as the ground (or counterpoise) there is no splitting of power at all. It does carry 100% of the power at a different phase from that transmitted.

I do agree that you don't want to run too much power, but the possibility of arcing exists with respect to any non-bonded joint, including flight-control cables and wiring.

The situation is really no different than operating from a car, except that RF interference will have a markedly different impact when you're flying.
 
wsuffa said:
You can center load if you install a center load in the long wire (whether old ADF sense or trailing wire).
Click to expand...

Yes you can, but IMO the physical size of the required inductors would be somewhat incompatible with the 100 Kt+ wind in the airborne application. I suppose you could apply streamlining, but there's also issues with mechanical resonance etc. Personally, I'd rather not have a few pounds of stuff whipping around near the airplane in the middle of a wire.

Loading really does nothing for radiation efficiency of the antenna - that is fully defined by the radiational length/area of the antenna - loading is simply there to get a good match to the transmitter. A good match to the transmitter is important because maximum power transfer happens within the final amplifier only when it is matched 1:1.

Antenna height at HF is only a factor if you can create a lower angle to the horizon, thereby allowing further distance to skip.... which is why directional antennas on the ground tend to compress the signal towards the horizon. Or if you are high enough that you get fresnel-zone clearance, turning your HF communication into line-of-sight.

Shorter antennas tend to be much more omnidirectional, meaning more energy goes upward where it is wasted.
Click to expand...

Agreed.

BTW, the quarter-wave above ground is immaterial... remember that you're forming an artificial ground with the aircraft body.
Click to expand...

The reference to antenna height was (unclearly) meant to refer to ground bound antennas. Airborne unbalanced antennas must behave as you say.

Beg to differ. Because the airframe acts as the ground (or counterpoise) there is no splitting of power at all. It does carry 100% of the power at a different phase from that transmitted.
Click to expand...

I could be wrong, but my understanding is that an ungrounded counterpoise will carry all the power as you state, but it ends up radiating half. Either way the real issue is there will be a farily high RF current in the airframe if you are transmitting with high power. The results of that are probably difficult to predict given the irregular shape of the airframe's conductive paths.

I do agree that you don't want to run too much power, but the possibility of arcing exists with respect to any non-bonded joint, including flight-control cables and wiring.

The situation is really no different than operating from a car, except that RF interference will have a markedly different impact when you're flying.
Click to expand...

Oh, I hate to see the word impact used WRT flying!:)
 
lancefisher said:
I could be wrong, but my understanding is that an ungrounded counterpoise will carry all the power as you state, but it ends up radiating half. Either way the real issue is there will be a farily high RF current in the airframe if you are transmitting with high power. The results of that are probably difficult to predict given the irregular shape of the airframe's conductive paths.



Oh, I hate to see the word impact used WRT flying!:)
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It's the full power 180-degrees out of phase. I prefer to think of the radiation from the whole system as one entity, because that's what you've really got in the far field. Elimination of the ground/counterpoise will not eliminate 1/2 of the raditated energy from the system. In a true dipole, yes, you get half the radiation off each side of the dipole, but that's not really what we have here.

(I shall scrape the remaining cobwebs out of the brain shortly).

The real issue, though, is the amount of current (and induced voltage) floating around the airframe (without respect to the amount of radiation eminating from the antenna or the airframe).

BTW, if you think single-pilot QSO's are distracting with voice, there are some folks that have operated single pilot CW from the air. Woof.
 
Every time I read stuff like this I flashback to Maxwell's equations.

Weirdly enough, I know a guy who put them all to music. It's a rather catchy song too.
 
Been browsing around for a few weeks now, figured I might as well join. Great little discussion you all have going here.

Bob, I too thought that a 2m rig would give a cheap phone in the cockpit. I tried it once with a 2m handheld, and the call quality was marginal, although we were able to exchange the information needed. Maybe that was because of the handheld or just because all the noice in the cockpit, who knows.

It did, however, remind me of a flight with a good friend who said I was crazy for doing it, and then proceeded to show me his cheap way of providing phone service to himself in the cockpit when needed. He switched the com2 over to Unicom at the airport a little ways in front of us, and asked the kind folks there to call his house and let his wife know we were 30 minutes out, and to request that she meet us at the airport with his vehicle. After several minutes, we received confirmation back that they had talked to his lovely wife, and she would happy to meet us, provided we bought dinner. After all that, he looked at me and said "All you young kids just don't understand that all those fancy gadgets take up space, and everything you need is already in the plane."

I have to admit, I had never thought of doing this, but I no longer use a cell phone or amateur phone patch in the cockpit. I've not come across anyone yet who says they won't do it. You can't have a long conversation this way, but it gets the job done for short advisory phone calls, which is all I ever really used it for in the first place.

Steve
KC0NHH
 
Yeah; I'm gonna have to bite the bullet and get a Sat phone some day. My main issue is that I don't want to take the time and mental energy to learn the technology. I believe I could probably buy used equipment on ebay and sign up for a satellite-reasonable subscription...and be 2k-4k out of pocket when I make my first call.

The way I have done things for years is: go to an expert and say, "You do it." But the problem here is when I asked how much that would cost for a phone, the answer was, "Oh, about $20,000."

An autopatch would, at best, be something for quick, little, urgent calls...like, "Honey, I'll be an hour late." And what I need is something more reliable...and with better quality.

Not that I'm going to be doing business while flying a missed approach :) but for those hours-upon-hours of straight and level, above 12,500, with George flying...
 
stcurtis said:
I have to admit, I had never thought of doing this, but I no longer use a cell phone or amateur phone patch in the cockpit. I've not come across anyone yet who says they won't do it. You can't have a long conversation this way, but it gets the job done for short advisory phone calls, which is all I ever really used it for in the first place./QUOTE]

IIRC the thread starter was about working a contest while airborne, not how to provide cheap airphone service.

WRT unicom relay's, I've had far less success than you. These days with ASOS and all, it seems pretty rare when an FBO will even answer a radio call and I have had some answer but refuse to make a landline call (too busy at the moment) especially if it's long distance which is quite often the case unless your contact is really close to the airport. And given the short range of most FBO unicoms, I've found that by calling my party on the cellphone as soon as I clear the runway gives almost the same notice.
Click to expand...
 
RobertGerace said:
Not that I'm going to be doing business while flying a missed approach :) but for those hours-upon-hours of straight and level, above 12,500, with George flying...
Click to expand...

One of the services offered by Avidyne on their EX-500 is text messaging to and from the airplane. I suspect this works a lot better when at cruising altitude than near the ground, but it might even work pretty well then given the short burst nature of the traffic. I'd think that'd be handy for those "I should be home by 8:30, what's for dinner" queriess.
 
Lance,

Yeah; but that is $15k before installation...for the $20k I'd rather have the phone ;)
 
I'm confused... What does $20K buy you? Iridium handsets are FAR less than that. I know a guy who has one in his 210 for weather and voice. IIRC, they run about $1500 (or less?) and less than $1.00/min.
 
Autopatch repeaters generally require paid membership.
911 calls may be free. Procedures and frequecies vary according to the individual repeater. The ARRL repeater handbook would be a good place to start.

For nomal contacts just CQ on 146.52.
 
sshekels said:
I'm confused... What does $20K buy you? Iridium handsets are FAR less than that. I know a guy who has one in his 210 for weather and voice. IIRC, they run about $1500 (or less?) and less than $1.00/min.
Click to expand...

$20k buys a phone that's actually installed in the plane and integrated into the audio system IOW what you might see on a bizjet or cabin class piston twin.
 
Ahh! Wow - Although I guess I should not be surpised at the cost. I think I'd so the handheld and figure a way to hook it up...

Aircraft are a wonderful way to spend lots of cash on cool toys!

S.
 
RobertGerace said:
Yeah; I'm gonna have to bite the bullet and get a Sat phone some day. My main issue is that I don't want to take the time and mental energy to learn the technology. I believe I could probably buy used equipment on ebay and sign up for a satellite-reasonable subscription...and be 2k-4k out of pocket when I make my first call.

The way I have done things for years is: go to an expert and say, "You do it." But the problem here is when I asked how much that would cost for a phone, the answer was, "Oh, about $20,000."

An autopatch would, at best, be something for quick, little, urgent calls...like, "Honey, I'll be an hour late." And what I need is something more reliable...and with better quality.

Not that I'm going to be doing business while flying a missed approach :) but for those hours-upon-hours of straight and level, above 12,500, with George flying...
Click to expand...

Last time I set one up (couple weeks ago) I got an Iridium phone with extension antenna and PC cable for data for $1600. Service is still $1.50 a minute voice or data.
 
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