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Wing Tip Internal Antenna

jliltd

Well Known Member
My RV-8 has an antenna glassed into the inside of the wing tip. It looks to be a copper foil strip maybe 28" long and is horizontally phased. It does not look like any of the Bob Archer type. An RG 58 coax pigtail comes off it and goes to the instrument panel area. It is currently unused. It was originally used before a complete instrument panel and avionics makeover a few years ago and that was before I owned the aircraft. I need a VOR/ILS antenna for a GTN 650 and was hoping this might work. I might take the opposite wing tip off to see if there is also one there. Do the hidden wing-tip antennas for VOR every have one element in each wing tip? Or do they only have them in one wing tip. This could be a Comm antenna even though it's not vertical.

Are there other wing tip antenna designs out there other than Bob Archer made of copper?

Jim
 
I will take a picture of it tomorrow. I need to take the other wing tip off to see if there is another antenna in it.
 
Sounds like a MB to me too. Look up the Archer vor antenna on Aircraft Spruce so you know what you’re looking for. Properly installed they’re good antennas.
 
So I finally dug through the aircraft documents and found information on my RV-8's internal wing tip nav antenna. So attached is a photo of the wing tip antenna drawing and documentation. The small print at the bottom indicates this is a Van's Aircraft drawing dated November 2004. it mentions in the instructions the antenna can be used for VOR or UHF. Naturally I would be looking for the VOR tuning (25"). This antenna model appears to be a different design than the more common Archer wing tip antennas.

I plan on using this for my GTN 650 installation for the Nav side.

I see one thing in the drawing that differs from my install. Instead of using a female bulkhead fitting in the wing tip rib (which the drawing mistakenly calls a "male" bulkhead fitting - it's all about the center pin), the builder has a free female BNC pigtail on the end of the coax coming out of the wing. Could that cause a problem? In other words is the bulkhead BNC fitting providing some sort of ground plane that might have been compromised by the builder's bypassing the tip rib with a free floating pigtail?

I would love to hear from anybody who has successfully used this model of VOR antenna. It is already installed with a coax ready to go under the instrument panel from the original builder's avionics stack.
 

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Well I’ll be the first to say I don’t understand this. I would think the unterminated service loop would cause problems. I’d have attached a very short wire from the shield to the end rib, where the coax ends (and the center conductor goes to the foil). It doesn’t hurt to try it. Modern receivers are incredibly sensitive and low-noise, almost anything will work to some extent. But if it were me I’d just put in an Archer type.
 
Why yes. Yes I do have one of those. It's at a friend's hangar at an airport across town but that's a great idea.
 
One of the things that bugs me about installation drawings sometimes is the designer doesn't mention why things are done the way they are, and barring that they don't even make a note on the drawing that a detail is an important part of the installation, like the mentioned bulkhead fitting on the tip rib. So some builder just pulls a coax through the wing with a female connector and decides why spend the time and effort on a bulkhead fitting when there is a perfectly good coax end ready to go on the cable. Most homebuilders want to know all the details and not just, "do it the way the drawing shows" and this would be an example where a neophyte may get crossed up.
 
Why yes. Yes I do have one of those. It's at a friend's hangar at an airport across town but that's a great idea.

Hook it up at the radio end so you'll get a view of the entire systems' performance.

...and report back your findings; this stuff is very interesting.
 
WILCO. It will be after KOSH as I am not going to take down the panel again until I get back.

Thanks for the great idea.
 
Home brew antenna

It should work just fine. As an Amateur Radio Operator and a former Technician, I've made lots of antennas for all sorts of uses and bandwidths. I used to hunt stuck transmitters long ago and still have my Yagi made with aluminum arrows. Worked great. All the parts slid into a square aluminum tube for storage.
 
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