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advice on mounting nav antenna

prkaye

Well Known Member
I'm going to be installing a Nav Antenna that i'm getting from SteinAir. I'm looking for advice on mounting it. I have seen here that many people put these in the wingtip. Questions:
1) What is the best way to attach the antenna in the wingtip - epoxy?
2) Does the orientation of the antenna matter?
3) What about ground-plane, if installing in the fiberglass wingtip?
Thanks!
Phil
 
I'm going to be installing a Nav Antenna that i'm getting from SteinAir. I'm looking for advice on mounting it. I have seen here that many people put these in the wingtip. Questions:
1) What is the best way to attach the antenna in the wingtip - epoxy?
2) Does the orientation of the antenna matter?
3) What about ground-plane, if installing in the fiberglass wingtip?
Thanks!
Phil
I will answer with my experience, which has been very successful. Others with more antenna expertise may also comment.
1. I used hinges to install my wingtips and attached the Archer antenna using the same rivets used to attach the hinge half. I also put a piece of fiberglas tape across the long leg to keep it from flopping around.
2. Yes. Follow the installation instructions for the orientation and the wire routing to be successful.
3. Just ground the antenna properly. My antenna gets an adequate ground to the wing through the two sides of the hinge. Others have added a separate ground wire to the wing. The fiberglas is transparent to the radio frequency.
 
I'm going to be installing a Nav Antenna that i'm getting from SteinAir. I'm looking for advice on mounting it. I have seen here that many people put these in the wingtip. Questions:
1) What is the best way to attach the antenna in the wingtip - epoxy?
2) Does the orientation of the antenna matter?
3) What about ground-plane, if installing in the fiberglass wingtip?
Thanks!
Phil

The most common wingtip antenna is called an ‘Archer’, after its original designer, Bob Archer. Technically it’s a bent quarter wave, working against a ground plane, and fed by a gamma match. So
1. There is a ground leg on this antenna, which must be electrically connected to the metal end rib (the rib will serve as the ground plane). The instructions suggest using nutplates and the wingtip attach screws to connect the ground leg to the rib. Others have riveted an aluminum angle onto the end rib, and mounted the ground leg to the angle. Some just let the rest of the antenna lay inside the wingtip; some use tape or a strip of fiberglass/epoxy to keep it from bouncing around.
2. VOR and ILS signals are horizontally polarized, so the antenna should be horizontal. Note com signals are vertically polarized, which makes it harder to use wingtip antennas for com signals - there isn’t enough vertical room.
3. The ground plane is the vertical end rib.
The instructions say how to run wires to nav lights, if you must run them across the antenna. But it’s usually best to mount the antenna aft a bit, and avoid the wires altogether.
Some EAA chapters may have an ‘antenna analyzer’ you can borrow, to tweak the matching network (‘gamma match’) for optimum performance. But if you follow the instructions it’s probably not necessary.
Examples of installation errors I’ve seen:
1. Mounting the ground leg 8” away from the end rib. It needs to be close, and in electrical contact.
2. Reversing the ground leg and radiating leg! Expect poor performance!
 
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This mounting works well.

As previous posted, do not run the nav/strobe wire along the antenna as shown in the Archer instructions. No need to temp the RFI noise gremlins if you don’t have to.

The wingtip slides over the antenna. No need to disconnect wires when removing the tip.

On this photo you’ll note this homebrew antenna extends much further out from the last wing rib than the Archer antenna. This takes full advantage of the room in this wingtip. If you have an antenna analyzer to tune it you can modify the antenna to do the same - if not leave it as is.

Carl
34-A989-E3-D914-4-D08-A863-6-DEABF017689.jpg
 
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Hi Phil - I haven’t tested mine yet but have some pix Lee Archer sent me about proper and improper routing of wiring esp. lighting. They amplify what instructions discuss. PM me with your email and I will send.

Warm regards,
 
I attached mine to the wingtip with nut plates as per the instructions. I wrapped metal tape around the edge of the wingtip prior to riveting to provide more ground contact area when the tip screws into the wing. The end of the antenna is held in place with some strips of fiberglass cloth.
 
I've installed the Archer antenna in my wingtip as described by many here -- shifted aft, separated from the light wires, riveted via the same rivets that attach my hinges.
While testing inflight reception off a few VOR's and the local ILS, I see a "wag" of +/- 3-5 degrees on the CDI; the glideslope indicator also wags 1/4 to 1/2 dot either direction. This is into a 650Xi.
I'm curious if the wagging has been noted by others using this antenna/installation?
 
I've installed the Archer antenna in my wingtip as described by many here -- shifted aft, separated from the light wires, riveted via the same rivets that attach my hinges.
While testing inflight reception off a few VOR's and the local ILS, I see a "wag" of +/- 3-5 degrees on the CDI; the glideslope indicator also wags 1/4 to 1/2 dot either direction. This is into a 650Xi.
I'm curious if the wagging has been noted by others using this antenna/installation?

Interesting as the new owner of my RV-10 noticed the same thing after he upgraded the 650 to the 650XI (Oshkosh show special). That plane has a homebrew wingtip antenna that I’ve built for half a dozen RVs - and all work very well.

Note however he got the same wobble while on the ground at an airport with a VOR Test Facility. While this does not fully rule out the drift being related to the antenna, the antenna mounting or such, it does leave open the door to look for other causes.

Not yet fully explored is RFI from other electrical/electronic components in the plane. Here turning stuff off and observing the change in VOR indication is the best approach.

Carl
 
A very good explanation by Bob and here is my 2 cents in addition.

Instead of riveting it to the hinge or nut plates, I install it in a way that it can be removed without any pain, should that ever be required. Also be advised that hinges are not conductive unless the top coating has been removed.
 
Installed mine on the same rivet line as the nutplates and reinforcing strip used to screw on the wing tips for proper grounding. The rest of the antenna is attached with click-bond fasteners. Works great with my GNC-255. No wag on the LOC or GS, rock solid. 100NM+ reception on VOR frequencies 7500 feet and above.
 

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I've installed the Archer antenna in my wingtip as described by many here -- shifted aft, separated from the light wires, riveted via the same rivets that attach my hinges.
While testing inflight reception off a few VOR's and the local ILS, I see a "wag" of +/- 3-5 degrees on the CDI; the glideslope indicator also wags 1/4 to 1/2 dot either direction. This is into a 650Xi.
I'm curious if the wagging has been noted by others using this antenna/installation?

Quick test: beg, borrow, or steal a hand-held that gets and decodes vors and/or ILS signals. Unplug the nav coax from the 650, plug it into the handheld, go fly. Still see the wag? Then ant installation issue. No wag, 650 issue. I run an Archer into an SL30, no wag as you described.
 
Quick test: beg, borrow, or steal a hand-held that gets and decodes vors and/or ILS signals. Unplug the nav coax from the 650, plug it into the handheld, go fly. Still see the wag? Then ant installation issue. No wag, 650 issue. I run an Archer into an SL30, no wag as you described.

Great idea Bob -- turns out my handheld has a rudimentary NAV mode, just need to order an antenna adapter and give this a shot.

I did sand the hinge for electrical contact, and checked continuity with a meter. Wouldn't be hard to add a ground strap between the antenna and the end rib. Or, just remount the antenna to the rib as shown up-thread.
 
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