My fuselage is almost finished and I am starting work on the wings. I am considering using one of the antennas that can be placed inside the wing and does not need a ground plane? I am looking at the one is Spruce call "Advanced Aircraft Electronics High Gain Aircraft Antenna Systems". It's about $125. I am aware of mounting locations for a standard mount antenna but I would like to hide the antenna to my hand held radio. Anybody got any experience with these antennas?
Dennis
Antennas without a ground plane
antennas
I put the antenna in the rear of the fuselage, behind the baggage area. Made an aluminum ground plane attached with clamps to the lower tubing and used a standard com antenna. Worked just fine. There maybe a blind spot directly behind the tailpost, but a slight turn will fix that. On one occasion in 10 years I could hear departure calling, but they could not hear me until I made a slight turn from course.
Grady
Grady
Dennis,
Like Grady, I know of several planes using this style. I also know of one who put screen wire inside the tailcone (lighter than aluminum, even if just a bit!) and mounted the antenna in this manner.
Nice thing is that this way your antenna does not show from the outside but transmission and reception is very good.
My Chief has some aluminum foil spread out at the base for a ground plane. Antenna is mounted on the top of the plane and it works fine but in the future I will probably do one inside the tailcone like Grady and the others. Looks better and less drag.
Joe A
Like Grady, I know of several planes using this style. I also know of one who put screen wire inside the tailcone (lighter than aluminum, even if just a bit!) and mounted the antenna in this manner.
Nice thing is that this way your antenna does not show from the outside but transmission and reception is very good.
My Chief has some aluminum foil spread out at the base for a ground plane. Antenna is mounted on the top of the plane and it works fine but in the future I will probably do one inside the tailcone like Grady and the others. Looks better and less drag.
Joe A
Dennis,
I stopped thinking years ago, kept getting a headache when I did it! Besides, the young copilots I keep getting these days feel that they can do all the thinking in the cockpit anyway!
Grady might have tried this but I have not, but hope he chimes in with more info. Remember that if you mount the base of the antenna into one rib I believe that this will also tie it into the leading and trailing edges, thus making the entire wing structure one very large "ground plane" using the ribs and such. Not sure how this would transmit or receive with the antenna wrapped inside the ground plane. Need some more experienced in "sparks chasing" and avionics to answer this one.
Pls let us know what you find out. Could be an interesing mod!
Joe
I stopped thinking years ago, kept getting a headache when I did it! Besides, the young copilots I keep getting these days feel that they can do all the thinking in the cockpit anyway!
Grady might have tried this but I have not, but hope he chimes in with more info. Remember that if you mount the base of the antenna into one rib I believe that this will also tie it into the leading and trailing edges, thus making the entire wing structure one very large "ground plane" using the ribs and such. Not sure how this would transmit or receive with the antenna wrapped inside the ground plane. Need some more experienced in "sparks chasing" and avionics to answer this one.
Pls let us know what you find out. Could be an interesing mod!
Joe
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Jody Wittmeyer
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Stained glass supply shops, hobby shops carry a copper foil tape. Very thin, very light weight, available in different widths. I use 1/4 inch. Makes a very good ground plane. It would stick to formers, ribs, fabric, etc. We edge our glass pieces with it so the solder has smethig to stick to. Try as I might, never could get the stuff (solder) to stick to the glass itself. 
Blue Skies and Stay Safe, and preserve 'em
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Nathan K. Hammond
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I'm not sure mounting the com antenna sideways works. Something about how the frequency waves work,
comms run up and down and navs work left and right.
Plus, I think running it between ribs might blank out too much space.
Personally I would like to try one of those long narrow antenna's in the belly.
But a regular antenna works fine.
nkh
comms run up and down and navs work left and right.
Plus, I think running it between ribs might blank out too much space.
Personally I would like to try one of those long narrow antenna's in the belly.
But a regular antenna works fine.
nkh
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Paul Agaliotis
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kevin mielke
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Here is some info I have found on antenna location using Spruce's "Advanced Aircraft Electronics High Gain Aircraft Antenna Systems". This antenna does not use a ground plane. I sent an email to Comant asking for there advice on locating a ground plane antenna horizontally on the last wing rib between the wing bow.
What cable length is recommended for the antenna ?
Any length can be used. This antenna is impedance matched to 50 ohms to allow you to use any length required.
Can I use it in the plastic or fiberglass wingtip of a metal airplane ?
Yes, but the antenna must be as far from the metal wing as possible.
I thought the com antenna has to be vertical to work.
For maximum sensitivity, this is best. The VHF-5 antenna has a higher gain than others but still when mounted in the horizontal plane the resultant sensitivity is reduced but useable.
Can I mount the antenna on a metal part of my airframe?
No ! This antenna works best when separated from all large metal objects. Mounting it on any metal destroys its antenna properties.
Some people have good operation with a ground plane working with their antenna, does this one do the same?
No, any ground plane will destroy the effectiveness of this antenna.
My fabric airframe is completed, where is the best location for the antenna? Mount it on a wood brace in the fuselage behind the cockpit. Fasten one end to a location on the lower part of the fuselage frame corner. Then fasten the other end to the opposite or diagonal part of the inside of the upper frame corner. Fasten the antenna to this installed piece of wood.
Should I be careful of the angles at which I mount this wood?
No. As long as the antenna is in the same plane as the plane of rotation of
your propeller, it'll work.
What happens if I mount the antenna on one of my wood stringers on the fuselage?
The maximum range will always be off to the sides and the minimum range will be ahead and behind you.
What happens if I mount the antenna on my wood spar in the wing?
The maximum range will always be ahead and behind you and the minimum range will off to the sides.
What if the antenna has to be mounted with a bend to fit in the space I want to use?
Curving the antenna will fill in those minimum range areas mentioned above at the slight expense of the maximum range.
Can't I have both?
No, only a fixed amount of energy can be radiated. If you redirect energy to fill in holes in the pattern you must remove some from one part of the radiation pattern to fill in the other.
Why do I have to keep it away from metal things?
Any metal alters the characteristics of the tuning and pattern in unpredictable ways. Each airframe installation is different, so we recommend that you use tape and experiment with locations until you are satisfied with the operation.
Where is a good location in my fiberglass fuselage?
Put the com antennas on either side in the tail cone, & if the fuselage isn't
tall enough bend the antennas to resemble the letter"C". If you are using two, stagger them on opposite sides and try to have about 24 inches or more in the stagger.
Why haven't I seen this type of antenna previously?
This design has been in operation since 1981 but in response to consumer demand they are now being produced for the non-metal airframe market.
DIAGRAMS
What cable length is recommended for the antenna ?
Any length can be used. This antenna is impedance matched to 50 ohms to allow you to use any length required.
Can I use it in the plastic or fiberglass wingtip of a metal airplane ?
Yes, but the antenna must be as far from the metal wing as possible.
I thought the com antenna has to be vertical to work.
For maximum sensitivity, this is best. The VHF-5 antenna has a higher gain than others but still when mounted in the horizontal plane the resultant sensitivity is reduced but useable.
Can I mount the antenna on a metal part of my airframe?
No ! This antenna works best when separated from all large metal objects. Mounting it on any metal destroys its antenna properties.
Some people have good operation with a ground plane working with their antenna, does this one do the same?
No, any ground plane will destroy the effectiveness of this antenna.
My fabric airframe is completed, where is the best location for the antenna? Mount it on a wood brace in the fuselage behind the cockpit. Fasten one end to a location on the lower part of the fuselage frame corner. Then fasten the other end to the opposite or diagonal part of the inside of the upper frame corner. Fasten the antenna to this installed piece of wood.
Should I be careful of the angles at which I mount this wood?
No. As long as the antenna is in the same plane as the plane of rotation of
your propeller, it'll work.
What happens if I mount the antenna on one of my wood stringers on the fuselage?
The maximum range will always be off to the sides and the minimum range will be ahead and behind you.
What happens if I mount the antenna on my wood spar in the wing?
The maximum range will always be ahead and behind you and the minimum range will off to the sides.
What if the antenna has to be mounted with a bend to fit in the space I want to use?
Curving the antenna will fill in those minimum range areas mentioned above at the slight expense of the maximum range.
Can't I have both?
No, only a fixed amount of energy can be radiated. If you redirect energy to fill in holes in the pattern you must remove some from one part of the radiation pattern to fill in the other.
Why do I have to keep it away from metal things?
Any metal alters the characteristics of the tuning and pattern in unpredictable ways. Each airframe installation is different, so we recommend that you use tape and experiment with locations until you are satisfied with the operation.
Where is a good location in my fiberglass fuselage?
Put the com antennas on either side in the tail cone, & if the fuselage isn't
tall enough bend the antennas to resemble the letter"C". If you are using two, stagger them on opposite sides and try to have about 24 inches or more in the stagger.
Why haven't I seen this type of antenna previously?
This design has been in operation since 1981 but in response to consumer demand they are now being produced for the non-metal airframe market.
DIAGRAMS
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high time cub
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Hi Dennis.
http://www.pipercubforum.com/comms.htm
http://www.pipercubforum.com/comms.htm
You have to be carefull with the polarization of the comm antenna, vertical vs horizontal. I want to say that comm is vertically polarized and hence the standard use of vertical antennas. I do not think that a horizontal mounting to a wing rib would work the best. I have heard of 50-75% losses. It was very easy to mount the 1/4 wave ground plane antenna to a tube and then make a ground plane around it.
I too initially used aluminum foil as a ground plane glued to the inside of the fabric on the belly of the aft fuselage section. (spray glue works wonders.) I then grounded the aluminum foil. Although the antenna was mounted rigidly to a tube, the alumunim foil flexed. Worked great for the radio, but at each annual I would see the foil cracking and disintegrating from the flexing of the belly fabric. It got to be a pain to clean up and then replace the foil, so I mounted a thin aluminum ground plane to a couple of tubes with Adel clamps. End of mechanical woes.
If you really want to use a dipole copper foil antenna, I will try to find the dimensions for a comm antenna. I built one a long time ago for a fiberglass project. A web search for Jim Weir of RST Engineering will probably give you all the info you need. http://www.rst-engr.com/ Note that you need to find some toriods to "balance" the antenna. There should be lots of info on the web. The dimensions of the copper foil are must be tuned to the comm frequencies. Again the antenna will work best if mounted vertically or as close as possible. For me I was just as easy to mount a standard antenna. Of course you can make a 1/4 wave antenna too.
Grady
I too initially used aluminum foil as a ground plane glued to the inside of the fabric on the belly of the aft fuselage section. (spray glue works wonders.) I then grounded the aluminum foil. Although the antenna was mounted rigidly to a tube, the alumunim foil flexed. Worked great for the radio, but at each annual I would see the foil cracking and disintegrating from the flexing of the belly fabric. It got to be a pain to clean up and then replace the foil, so I mounted a thin aluminum ground plane to a couple of tubes with Adel clamps. End of mechanical woes.
If you really want to use a dipole copper foil antenna, I will try to find the dimensions for a comm antenna. I built one a long time ago for a fiberglass project. A web search for Jim Weir of RST Engineering will probably give you all the info you need. http://www.rst-engr.com/ Note that you need to find some toriods to "balance" the antenna. There should be lots of info on the web. The dimensions of the copper foil are must be tuned to the comm frequencies. Again the antenna will work best if mounted vertically or as close as possible. For me I was just as easy to mount a standard antenna. Of course you can make a 1/4 wave antenna too.
Grady