Can ground plane serve as remote compass mount?

[skysailor]

I am building a Glasair and am planning to construct a "shelf" attached to the sides of the fuselage in the back to provide a mount point for the remote compass units of a D180 and D100. It occurred to me I might make the actual shelf out of aluminum and perhaps mount both the ELT and transponder antennas to is as well since the large flat shelf would be a good ground plane. Would this cause problems with the remote compass? I understand from reading here I can mount two remote compass units as close to each other as I like since they will not interfere with one another. I am hoping the ELT and transponder antennas might also play well with others. Dynon, would this be OK?

 

[PhantomPholly]

Re: Can ground plane serve as remote compass mount

Mine works fine. My remote compass is mounted on a shelf in the tail cone which has a ground plane built into it and the primary comm antenna attached (a bent whip, the base of which is about 6" from the remote compass). I have watched for fluctuations when transmitting (GNS 480, like yours) and have observed no issues.

 

[PhantomPholly]

Re: Can ground plane serve as remote compass mount

Shhh! No revealing secret identities...

 

[skysailor]

Re: Can ground plane serve as remote compass mount

Post removed, reset Mode 4 and execute RTF protocol.

 

[PhantomPholly]

Re: Can ground plane serve as remote compass mount

You forgot to pass the Have Quick TOD!

 

[dynonsupport]

Re: Can ground plane serve as remote compass mount

I have to say I don't love the idea of a 200W transponder antenna right there by the EDC and the wiring. A comm antenna is only 6-10W.

We don't have any experience with this so I can't promise it will or won't work, but a transponder is a big pulse.

 

[skysailor]

Re: Can ground plane serve as remote compass mount

Fair enough. A separate ground plane for the transponder seems the better way to go given your concerns. Now for the fun part... could I located it below by a couple of feet? What distance would you like to see?

 

[PhantomPholly]

Re: Can ground plane serve as remote compass mount

My shelf is about 24" aft and 12" above the connection point for my xponder antenna (small 4" blade underneath the belly). It has a separate ground plane (aluminum plate) on the inside of the belly.

I've had no issue, but mileage may vary.

 

[skysailor]

Re: Can ground plane serve as remote compass mount

What size is the ground plane? Was the antenna already on the plane when you got it (and therefor the reason it is out in the slipstream)?

 

[PhantomPholly]

Re: Can ground plane serve as remote compass mount

About a 10" circle. That is standard installation on the Lancairs (blade xpndr antenna under the baggage area). Apparently plastic airplanes don't do as well with an internal transponder antenna, so even though the comm in internal they put the xpdr externally.

 

[jakej]

Re: Can ground plane serve as remote compass mount

Apparently plastic airplanes don't do as well with an internal transponder antenna, so even though the comm in internal they put the xpdr externally.

Wanna bet on that ? ;D

Jake J

 

[skysailor]

Re: Can ground plane serve as remote compass mount

Thanks for letting me know the transponder works OK from inside a plastic airplane jakej. All drag is bad but preventable drag has to be the worst!

 

[jakej]

Re: Can ground plane serve as remote compass mount

I should qualify that general statement - carbon fibre is the exception.

ALL of my antennas are inside the airframe of my IFR Glasair.

Jake J

 

[PhantomPholly]

Re: Can ground plane serve as remote compass mount

Wish I'd known that sooner. Wonder why Lancair decided that the best location was outside for that antenna on such an otherwise clean plane?