ADS-B Receive Antenna

[BravoFoxtrot]

I am planning a future install of a Dynon ADS-B receiver in my CTSW. My thought is to "stack" it in the same location as the ELT at the back of the tunnel and mount the antenna about 2' behind the ELT antenna on the bottom of the tail cone. So, two questions:

1. Is there a better location for the receiver and/or antenna?
2. Dynon says you probably need a ground plane for the antenna if it is mounted on a composite airframe. Since carbon fiber is "somewhat" electrically conductive, do I need a separate ground plane?

Any thoughts are appreciated. Thanks.

[FredG]

Check the thickness of the composite in the area you plan on installing the antenna.  When making the mechanical installation of the antenna, be sure that you have enough length of threads on the antenna to permit installation of the retaining nut on the inside of the fuselage.  Some antenna are designed for sheetmetal installation and may not accommodate the thickness of the composite fuselage.  Unless using really thin metal foil, the ground plane will also use up some of the available threads when installing the antenna.  

I don't know if you need a ground plane.  I installed one with my ADSB-in installation.

[BravoFoxtrot]

Good point on the thickness. Where did you install your antenna? Any thickness issues, and if so, how did you handle it?

[Madhatter]

I placed my antenna in the same location.  The threads were not long enough but when th bnc connector was installed it held the antenna tight as it is a Cam-lock type fitting. There is no load on a ball rod type antenna so I left it alone, never an issue. 

[FredG]

I used a blade style antenna from Delta-Pop Aviation that has two threaded posts for attaching it to the airplane.  I was able to install the antenna on the belly as you described.  

[BravoFoxtrot]

Two good options! Thanks for the replies Madhatter & FredG!!

[FredG]

FYI, my airplane is a 2006 CTsw.  And, as you inferred, the two threaded studs on the Delta-Pop blade antenna were just long enough to allow for mechanical attachment.

[BravoFoxtrot]

Thanks Fred. What did you use for a ground plane? Did you use a nylock nut and a star washer? Assuming the nut was flush with the stud, did this result in any crushing of the foam core? Did you use any metal spacers to keep from crushing the foam? Delta Pop says he can offer antennas with extended length studs if needed. If you were to do over would you go that route? If so, what length?

[FredG]

Does that part of the fuselage have foam core?  I recall it being quite solid.  I have to look to see if I used very thin aluminum sheet or copper foil for the ground plane.  Extended length studs seem like a good idea.  I think I recall that he supplies a rubber gasket to seal the antenna to the surface it is mounted on, extended studs may make fitting the gasket a bit easier.

[BravoFoxtrot]

No foam core? Ok, that was an assumption on my part, but it makes sense that it is solid back there. He may have used a gasket in the past but is currently recommending using a sealant.

[mikey70]

I added a ground plane to my antenna. Its a Garmin but the same principle applies. All my other antennas have ground planes as well. All you need is a thin sheet of aluminum 8 to 10 inches square on the inside of the airframe under the antenna. I also electrically bonded mine to the ground bus on the firewall. 

[BravoFoxtrot]

Thanks Mike.

[Tom Baker]

The fuselages are made in left/right halves, and the seam in the middle has no foam core.