Antenna

[mulwyk]

Spruce sells a 'Advanced Aircraft Electronics High Gain" antenna that is designed to mount INSIDE the structure of composite and fabric aircraft. No ground plane needed. They claim it outperforms everything on the market.

Does anyone have experience with this type of antenna? Where do you mount it? Does it really work?

Bob Gustafson

[lktiller]

Re: Antenna

I don't have experience with this particular antenna but with 50yrs electronics experience I've played around with a few antenna systems.
Don't be swayed by sales pitches! Do you really need the extra gain?
There's not enough loss from an internal antenna to justify the extra gain. As long as the internal antenna is not mounted right beside a piece of tubing.
The radios already receive signals from the next state, boosting that reception only means more interference.

The pigtail that come with most handhelds is sufficient at altitude. A rigid antenna is a bit more efficient.

a straight piece of wire (dipole antenna) taped to the fabric inside will work great. See attached pic. The overall length is 45 inches.

[M Jones]

Re: Antenna

I've had and used one of those antennas for a few years Bob. I got it directly from the manufacture (see add in the back of Sport Aviation), but it was much cheaper back then.

It seems to work OK, but I'm going to mount an old style bent whip through the bungy cord opening like some others have done to replace it. I fly with some other Taylorcraft folks and theirs seem much better with that set up.

[mulwyk]

Re: Antenna

Mike:
How did you mount your antenna? Inside the fuselage? Vertical or horizontlal?

Bob Gustafson

[flyguy]

Re: Antenna

Bob,
I would go with the "whip," that is the straight or bent stiff wire, and forget the fancy stuff. The dipole is a great antenna, but it is directional. The whip radiates in all directions unless you put it too close to any vertical grounded metal then it will be directional also. It works better with a ground plane, but will work with only a mounting plate also.
Darryl

[M Jones]

Re: Antenna

Mike:
How did you mount your antenna? Inside the fuselage? Vertical or horizontlal?

Bob Gustafson

Hi Bob,

I made a "temporary" mount that I still use to this day. I cut a 1/4" piece of plywood about 3" wide, and mounted the antenna to that. I then used a few wire ties to mount the plywood piece to the left side of the inside fuselage tubes behind the baggage sling. Because of the length, I couldn't get it as vertical as I wanted, so it's at about a 45-degree angle. Not optimal for Comm. I just didn't want to bond the antenna to the inside so I thought I'd try that. Like I said, it works well enough to go into controlled fields, but it seems to have a "dead" spot, like towards my 2 o’clock position especially. It becomes more obvious when doing some formation flying and trying to talk with the Lead if I'm on the left side I think. If I were to use one of these in a restoration, I would mount it as vertical as possible for best Comm use, probably back in the tail. I never had much interference using it with the Eiseman mags, which was the main reason I tried it out. The noise with the rubber ducky antenna was pretty high with the un-shielded mags.

[btbell]

Re: Antenna

Mike
Any change you could take and post some pictures? I am interested in some kind of antenna and have been asking around. I would prefer not to put an external on the plane if possible. Any pictures that anyone else has of their installations would also be appreciated.
Thanks,
Brian

[flyguy]

Re: Antenna

Actually there is probably some point on the welded tubular structure of a B model that would "load." The entire structure then becomes one big antenna.
I will have to bring it up as a challenge to one of my amateur radio friends. Between us we could probably scare up the right equipment to make the measurements. I suspect a correct point on the tubing to attach the radio antenna cable would let the transmitter "load" into it just fine.
Might give a really strange radiation pattern though!
Let me see if I can get anyone interested in this. I'll add it to my list of projects and if we get any results I'll share them with the group. Couldn't be much worse than some of the kludged antennas I've seen.
Darryl

[VictorBravo]

Re: Antenna

I just had a very experienced electronics engineer do some testing on my handheld installation. For what it's worth, a COM antenna should be oriented vertically for best performance. You can put a whip antenna on and use the metal wing root fairing strip as the "ground plane", if you ground it in turn to the steel tube frame. The diameter of the wire antenna does not matter, all it has to do is stay close to vertical. You could even use a piece of .025 carbon fiber rod from the local hobby shop as the "mast", and attach one thin strand of copper wire to it to function as the antenna. The length of the antenna is somewhat critical and it should be "tuned" to your radio and airframe installation. This is best done by a pro with the proper "SWR" meter to measure the radiation.

[M Jones]

Re: Antenna

Mike
Any change you could take and post some pictures? I am interested in some kind of antenna and have been asking around. I would prefer not to put an external on the plane if possible. Any pictures that anyone else has of their installations would also be appreciated.
Thanks,
Brian

Hi Brian,

No problem taking a picture and posting it. I may not get out to the airfield for a little while though because I'm traveling for the weekend (gotta go see Mom!), then for work all of next week. As soon as I can, I'll post something though.

[jrzangger]

Re: Antenna

When I restored my 46' BC12-D in 1997, my original intention was to keep it as close to original as possible. This meant no external antennaes! I put in two of the dipoles, one for com and the other for the ELT. I mounted them on wood strips and installed them just behind the baggage area as close to vertical as possible. As was mentioned on an earlier post, it was about 45 degrees from vertical. I am now using a bent whip mounted between the shock cord covers and consider it a much better installation. With the dipoles I was only able to get about 10 miles of usable range and now with the bent whip it is closer to 70 miles. No comparison! I still have the ELT on the dipole and can only hope it would work if needed!

[mhorowit]

Re: Antenna

I am now using a bent whip mounted between the shock cord covers and consider it a much better installation.

What are you using as a counterpoise (the part the braid is connected to? - Mike

[taylorcraftbc65]

Re: Antenna

This is probably only for about 1% of the members of this site, but what I have on Manu Sina is a standard aircraft whip that is on the top pf the aircraft between the wings.
When the aircraft was being recovered, a piece of the type of steel mesh that is used to keep stucco in place on vertical walls was cut to size to fit the "box" formed by the upper longerons, and the two spreaders that is used by some for a skylight.
The steel was mounted to the fuselage, with the whip being bolted to it. I plug my JRC nav-com into it, and it works as well nav and com as any panel mounted system would, all without any electrical system.
This idea could only be used by someone who was recovering their plane, but it works VERY, VERY well. I pick up VORs at 80 to 100 miles depending on terrain, power of the VOR, and my altitude.

[flyguy]

Re: Antenna

Man, all this suffering and pain over an antenna. Just bond (glue) a small sheet of aluminum with hole in it to the underside of the fabric, cut hole thru the fabric, bolt the whip thru the hole, connect the antenna coax and get back to flying--cheeesh.
Darryl

[mhorowit]

Re: Antenna

Darryl - some of us are using a 'wind-em-up radio' so we need to squeeze out the last fraction of a watt.

If no one comes up with a good answer, I'll run a heavy bare copper wire from the place the coax braid connects to the cowling, to the fuselage and clamp it in place. And I'll take someone else's advice and run a ground from the negative terminal of my battery box to the fuselage. I'll also take the opportunity to put a fuse in-line with the positive line. - Mike