Antenna Placement

[daveb]

Any suggestions on where to place a second VHF antenna on a currently flying Long-EZ without cutting anything open? This is for a second radio.

 

Dave

[Terry]

For a VHF nav just use a splitter. Many GA airplanes have only one nav antenna and use a splitter for the second nav and glideslope. For the VHF com there are RF switchers but they are not common. Back in the Vari-Eze days before the Long-Eze, RST had a com antenna with a built in balun. It was mounted on the floor at the back of the air brake torque tube support and the element was run up the back of the front seat and used a foil "X" on the floor for a ground plane. I had one of these in my Vari-Eze and it worked well. If RST no longer makes them I think I have one or two that I'll likely not use. This is a good reason to put in that second antenna even if KNOW your not going to need it. Some one else might.

[daveb]

The second VHF antenna is for coms. The aircraft is to be set up for IFR. The installer tells me it's best not too near headsets and preferably vertical. Seems a bit of a challenge.

[Cozy1200]

Dave,

 

I know your question is more of a placement issue, not an availability question.....

 

I have a complete roll of copper foil tape (100 feet) from RST for my cozy. I have the instruction from Jim as well. If you need some, let me know, I'm sure we can work out a fair price.... more slave labour!

[daveb]

Thanks Drew, noted ... maybe I shouldn't ask where to put it... but I still need to know. The installer was looking on the OUTSIDE of the airframe for placement

 

Plenty of things like this too:-

http://www.aircraftspruce.com/catalog/avpages/antennasystems.php

 

Would this work maybe under the floor? Pretty much hoping for advice on 'where to put it' as well as what to use without cutting anything.

[Terry]

I have also seen the dipole type antenna mounted on landing gear leg

[Cozy1200]

Dave,

 

I dug out the instructions tonight. It's over twenty pages long of detailed notes. I haven't read them all yet, but as you know most new planes embed the foil tape just under the skin.

 

One less than ideal solution would be to stick the foil to the prepared outer skin, then put a ply or two over it. Of course after that it would have to be refinished and painted. Not really any better solution, but still involved a lot of work. A brief glance shows you need about 20" of height for the copper foil antenna.

 

There are several interesting section that would probably be useful for you to see.

 

sorry still no better ideas on a retrofit.

 

We're in OZ, shouldn't we be saying aerial?

[argoldman]

I have also seen the dipole type antenna mounted on landing gear leg

 

If you mount the dipole in the landing gear, you need to make allowance for the flexing of the bow. Without this arrangement (sliding between two non abrasive surfaces), the antenna will work well, but only for a while until it tears.

 

Get that antenna in gear!!

[TMann]

Thanks Drew, noted ... maybe I shouldn't ask where to put it... but I still need to know. The installer was looking on the OUTSIDE of the airframe for placement

 

Plenty of things like this too:-

http://www.aircraftspruce.com/catalog/avpages/antennasystems.php

 

Would this work maybe under the floor? Pretty much hoping for advice on 'where to put it' as well as what to use without cutting anything.

Those are the antenna I'm using for com/nav. I just installed 2 in the leading edge of my canard.

 

You might be able to attach to the inside of the fuse in the console area. I'm not sure how well that would work for comm on account of the preferred arraingement is in the vert.

Just a thought.

[Marc Zeitlin]

The second VHF antenna is for coms. The aircraft is to be set up for IFR. The installer tells me it's best not too near headsets and preferably vertical. Seems a bit of a challenge.

In the COZY, the COM antennae go in the winglets (to be vertical). Depending upon how your winglets are set up, you might be able to install them on the medial side flange of the rudder attach recess. You need at least 40.6" - each LEG is 20.3", with no more than 1/2" between - see:

 

http://www.cozybuilders.org/ref_info/RST_82704.pdf

 

for info. Although the three metal hinges and a few other metal parts are close by, they're relatively small, so hopefully will not have a large effect. You could run the antenna wire across to the hinge side, then down to the wing level and forward to the light wire conduit. The copper tape could be applied to the inner flange and covered with one BID.

[Marc Zeitlin]

Plenty of things like this too:-

http://www.aircraftspruce.com/catalog/avpages/antennasystems.php

 

Wow. Why anyone in their right mind would spend $90 - $130 for something that you can put together in 10 minutes for $5 is beyond my comprehension. My $5 COM antenna lets me talk to ATC from 100 miles out or more, depending on altitude, and my transponder antenna is the same - ATC ALWAYS picks up the transmission, assuming they've got me on radar - how much better could these be? There's "better", and there's "more than good enough". I'm sure they work fine, but a total waste of money, IMO.

[TMann]

Wow. Why anyone in their right mind would spend $90 - $130 for something that you can put together in 10 minutes for $5 is beyond my comprehension.

'Cuz I can.

I use the foil antenna for my fuselage applications but I'm using the pricey antenna for comm & nav. Maybe overkill but it makes me feel as though I'm building a better product (even if it isn't so. )

[Lynn Erickson]

Those are the antenna I'm using for com/nav. I just installed 2 in the leading edge of my canard.

 

You might be able to attach to the inside of the fuse in the console area. I'm not sure how well that would work for comm on account of the preferred arraingement is in the vert.

Just a thought.

Com antennas need to be vertical at least one of the dipole elements. nav antennas should be horizontal. the best place for the Com is in the winglet. I have install them finished Long eze's on the back side of the winglet between the rudder and winglet and drill a hole from there to the wing wire conduit for the wire. the best is to use 1/2" wide copper foil tape. 14 gauge solid copper house wire also works very well.

[Neverquit]

I was told one time to install 2 antennas of each in case one breaks or fails. Strange thing is he told me to install 1 on each end. Such as one on each winglet, etc. If this sounds like a good idea, why not install two next to each other? Will the "spare" antenna interfere with the transmission of the working one?

[longezdave]

I would go with the suggestion you were given. That's what I did. I have a spare com antenna in one winglet and the coax is just sitting there ready for a connector if I ever need it.

 

I havn't seen any results of testing a set-up where there are two antennas in a single winglet. Theory suggests that the performance would be down because of the close proximity of the other antenna. The spare antenna would naturally be tuned to the same frequency as the transmitting antenna and therefore would absorb some of the energy leaving a shadow at best.

[mplafleur]

I was told one time to install 2 antennas of each in case one breaks or fails. Strange thing is he told me to install 1 on each end. Such as one on each winglet, etc. If this sounds like a good idea, why not install two next to each other? Will the "spare" antenna interfere with the transmission of the working one?

Yes, the close proximity of the other antenna will interfere and cause reflections. This is not recommended.

[TMann]

I was told one time to install 2 antennas of each in case one breaks or fails. Strange thing is he told me to install 1 on each end. Such as one on each winglet, etc. If this sounds like a good idea, why not install two next to each other? Will the "spare" antenna interfere with the transmission of the working one?

Hey Greg, if the comm antenna goes bad, use it as an excuse to transition to the blended winglet!

[jdubner]

Any suggestions on where to place a second VHF antenna on a currently flying Long-EZ without cutting anything open? This is for a second radio.

Dave,

 

I faced the same dilemma when adding an antenna for APRS (position reporting/tracking via VHF ham radio) in my very pretty Long-EZ. I decided to install a center-fed half wave vertical dipole on the rear-facing surface of the winglet that did not contain the existing com antenna. Here's the result viewed from the rear of the winglet, facing forward, and with the rudder held out of the way.

 

 

I came up with some copper foil and a ferrite choke from my junkbox but I understand RST Engr. sells these supplies. You can see the end of the choke "buried" in the winglet with the coax feedline passing through it and soldered to each half of the dipole. A small amount RTV secures the ends of the copper foil and connections.

 

The hardest part of the installation was drilling a hole for the coax in the winglet from the antenna's feed point to the area of the position light where I could access it and feed it into the hell hole via the spar. I welded a 1/4" drill bit onto a piece of 1/4" steel rod to make a 4-foot drill bit. Standing on a stepladder I took careful aim and drilled through the foam core until the tip of the bit was visible in the position light's hole (position light removed).

 

 

After that, snaking a leader for the coax through the spar was duck soup <g>. The end result was worth the effort. With 10 watts on 144.39 I'm always in range of a ground station even over the wilds of Idaho's Hell's Canyon:

 

http://www.mail2600.com/cgi-bin/track.cgi?call=K7JD-7&start=2008-1-21&stop=2008-1-22&elim=0

 

YMMV but I feel that VHF com performance will be similar.

[mfryer]

Very nice looking Long-EZ. Do you have any more pictures???

[jdubner]

Very nice looking Long-EZ. Do you have any more pictures???

Do I have any more pictures? DO I HAVE ANY MORE PICTURES? Like most of us I must have a zillion of them <g>.

 

I think those are about the best of the antenna installation but I have some of the panel, airplane in flight, taxiing, etc. if that's what you mean.

 

http://www.mail2600.com/Airplane/index.html

 

I haven't posted the recent ones of my APRS installation but would if there's interest. Or contact me via Email (but not PM).

[mfryer]

Thanks. I now see two challenges in my future. One is to have an aircraft nearly as beautiful as those on your site.

 

The other is to have less gray hair by the time it is complete. (I have a start, but if I strain hard enough I might be able to hold back additional gray).

 

I suppose I should also be happy just to have hair if there is any left as well.

[daveb]

Joe, looks really good. Thank-you. Any more pics or tips would be very helpful. Looks like this is my answer, as a non-builder it also leaves a lot of questions.

 

First concern is that the foil stays put, there is enough room to fit it and no danger of it coming adrift and fouling the rudder. RTV? I guess I'd better ask Drew about that when I go begging for some foil - I think he's only building one Cozy.

[Cozy1200]

I have a 100 foot roll of the foil that has a sticky back. I don't think I'd trust it alone. As Marc suggestioned, I would stick it in place then go over it with one or two plys of bid tape. Being inside the winglet area, it wouldn't need alot of finishing.

 

BTW, how are your soldering skills?

[jdubner]

Joe, looks really good. Thank-you. Any more pics or tips would be very helpful. Looks like this is my answer, as a non-builder it also leaves a lot of questions.

 

First concern is that the foil stays put, there is enough room to fit it and no danger of it coming adrift and fouling the rudder. RTV? I guess I'd better ask Drew about that when I go begging for some foil - I think he's only building one Cozy.

I can't remember much more from the installation and I think RTV was all I used. But that was during my "Pliobond phase" so I may have used some of that tough contact cement on the copper tape/winglet bond. Certainly no fiberglass cloth or epoxy. In the first picture you can see the shape it's in after 5 years and 670 hours flying time.

 

In any case, it's hard to not inspect it during each preflight -- it's right in my face when I inspect the rudder.