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Another antenna question...

bob888

Well Known Member
Two comm antennas...can they be mounted under the R and L rear seats and function adequately? Anyone have that setup with or without problems?
 
This seems to be a common setup. I plan on doing it this way on my -10. I have it set up this way on my -6A and they work fine. I've had no issues and I like how they are tucked out of the way.
 
The only problem with that location as I see it is access to replace the antenna and/or antenna cable in the future. I know the arguments for it, but I always out them under the pilot and copilot seats with great results on a dozen RV-10's.
 
Agree with Jesse - under the rear seats makes maintenance hard.

I mounted both bent whip comm antennas along the tunnel, one in front of the other, both aft of the forward wing spar, one on the left edge of the tunnel and one on the right edge. I used a piece of joggled aluminum going over the tunnel rib flange, sharing the rib to skin rivets as a backing plate. Access is easy, just have the flap motor and control tubes installed before selecting the antenna mounting locations to avoid interference. The XPDR antenna is mounted under the co-pilot seat. The ADS-B antenna is just aft of the baggage compartment bulkhead (as is the ADS-B receiver). Marker Beacon antenna is a simple wire tie wrapped under the engine and connected to a BNC bulkhead fitting on the firewall. It works well.

Warning - these antennas are severe eye hazards for hangar dogs and pilots cleaning the airplane belly. Slide a put a piece of tubing over each antenna for protection.

Carl
 
Agree with Jesse - under the rear seats makes maintenance hard.

C'mon guys, aren't we homebuilders of experimental aircraft? :D

Just put in an access panel like many of us have done for the step bolt. It makes maintenance real easy and takes less than thirty minutes to fabricate.

bob
 
Put both mine under front seats and out as far as I could without enterfering with the leg fairings.
 
So is rear seat vs front seats just a preference thing?

I'm going to be installing an Airflow AC system so there will be a condenser essentially under the rear seats. I could still put antennas there but figured I would space stuff out a bit and put the comm antenna's under the pilot co-pilot seats.
 
I have had, on a couple of occasions, poor/weak communications on the ground with the under the belly antenna. And once, in a descent pointed right at the tower, weak communications with the tower while airborne. All due to shadowing by the fuselage and all corrected by a small turn.
 
I originally had both on the belly but now I have my #1 com on top and #2 on the belly. Eliminated occasional poor comm on the ground.

Don Bodnar
 
I read that some people had issues with comm on the ground. Seemed to be the minority though. What antenna do you use on top and where do you put it? I assume you drill through the cabin top and run the antenna under your headliner or something...
 
I read that some people had issues with comm on the ground. Seemed to be the minority though. What antenna do you use on top and where do you put it? I assume you drill through the cabin top and run the antenna under your headliner or something...

I have one antenna on top of the tailcone, on the centerline about 3 inches behind the baggage bulkhead (a Rami AV-10 paired to an SL 30). I extended the ground plane onto the cabin top with 3 pieces of 1/4" copper foil. My second antenna is a bent whip on the bottom of the right wing behind the spar in the first inboard bay (AV-17 paired to a GTN650). I've had no comm issues with either one on the ground or in the air.

Note: I originally had planned for 2 bent whips under the rear seats - even went as far to fab and install the doublers and drill the mounting and connecter holes through the bottom fuse skin. Then I decided I wanted to add a belly cargo pod so all that work was for naught plus I had to rethink my entire antenna and wiring layout. The rest is history.
 
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I read that some people had issues with comm on the ground. Seemed to be the minority though. What antenna do you use on top and where do you put it? I assume you drill through the cabin top and run the antenna under your headliner or something...

As Todd noted, if you install a vertical com antenna on the fiberglass top, you need to provide a ground plane for it (something like the spokes of a bicycle wheel, or solid, conductors attached to the coax braid at the antenna's base). I think it's easier to mount to the aluminum tail cone, behind the baggage area (again, as Todd did, or even a bit further back). Longish runs of coax are not an issue at com frequencies. Personally, I put in an Archer com (with as much vertical component as I could get) in the wingtip. I know I am in the minority here, and it is not as good as the whip, but for me it's good enough for a #2 radio.
 
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