What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

Distance between Dynon and Garmin GPS Antenna/Pucks

Lynnb

Well Known Member
I searched and couldn't find an answer on the distance between my two GPS Antennas, one being the Dynon SV-GPS-2020 and the other being the Garmin GA35. I know that per the manuals the Dynon needs to be 36? from any transmitting (COM) Antenna and the GA35 needs to be 24?. What I can?t figure out is what should be the minimum spacing between the Dynon and Garmin GPS pucks be.

Thanks in advanced,
Lynn
 
The install manual for the GDL-82 WAAS antenna says 9" is the minimum to any other passive (GPS or XM) antenna.
 
Ok, my current plan has them about 12" apart so sounds like it will work.

Thanks,
Lynn
 
why the distance?

I planned on side by side in the engine compartment with a mount on firewall will that work?
 
I planned on side by side in the engine compartment with a mount on firewall will that work?

I can't speak for others, but I have a COM antenna mounted on my rear upper deck and I can get 24" away from it with the Garmin and still have it on the aluminum skin, to get 36" away from it, puts the Dynon on the fiberglass top. I had kicked around the idea of putting the dynon under the cowling, even ordered the bracket that the RV12 plans use for it, but in the end decided it would be easy to mount on the cabin top. Now if I hadn't mounted a top COM antenna, I would have just stuck them both back on the back deck.
 
I can't speak for others, but I have a COM antenna mounted on my rear upper deck and I can get 24" away from it with the Garmin and still have it on the aluminum skin, to get 36" away from it, puts the Dynon on the fiberglass top. I had kicked around the idea of putting the dynon under the cowling, even ordered the bracket that the RV12 plans use for it, but in the end decided it would be easy to mount on the cabin top. Now if I hadn't mounted a top COM antenna, I would have just stuck them both back on the back deck.

The Dynon puck does not need a ground plane so it can go on the cabin top. I can't remember if the Garmin puck needs a ground plane, but it does require a minimum cable length and a special grounding mesh if installed on a non-conductive surface (e.g., the cabin top) so installing it on the tailcone makes good sense. I have my comm-1 antenna (with a ground-plane extension up onto the cabin top), behind that the garmin puck (can't remember minimum distance but adhered to it), and behind that the ELT antenna on top of the tailcone, and my Dynon-2020 puck between the doors on the cabin top. I've had no performance issues on any equipment.
 
Last edited:
The Dynon puck does not need a ground plane so it can go on the cabin top. I can't remember if the Garmin puck needs a ground plane, but it does require a minimum cable length and a special grounding mesh if installed on a non-conductive surface (e.g., the cabin top) so installing it on the tailcone makes good sense. I have my comm-1 antenna (with a ground-plane extension up onto the cabin top), behind that the garmin puck (can't remember minimum distance but adhered to it), and behind that the ELT antenna on top of the tailcone, and my Dynon-2020 puck between the doors on the cabin top. I've had no performance issues on any equipment.

Thanks Joe.
 
I planned on side by side in the engine compartment with a mount on firewall will that work?

I installed my Dynon and Garmin under the cowl and have over 12" between them. I believe that it was in the Garmin manual that stated it needed at least 12" between GPS pucks.

I should be able to get the oil filter off with the GPS as they are. If I need a little more room, the GPS rack comes off with the removal of the 4 screws.

FP25082017A00016.jpg


FP25082017A00017.jpg


http://www.kitlog.com/photos/project_2399/full/FP25082017A00018.jpg
 
I installed my Dynon and Garmin under the cowl and have over 12" between them. I believe that it was in the Garmin manual that stated it needed at least 12" between GPS pucks.

I should be able to get the oil filter off with the GPS as they are. If I need a little more room, the GPS rack comes off with the removal of the 4 screws.


Personally, I wouldn't put them here. The distance between them may be fine but the airplane itself will shadow any signal coming from the rear. In other words, a satellite signal from the back will be invisible. For travel on the ground all we need are a few satellites in view to get a good 2D location fix. In the air we want as many satellites in view as possible in order to get a 3D location. And the further apart those satellites are from each other the better the 3D fix. That means satellites overhead along with satellites at low angles (closer to the horizon) together give us the best position in 3 dimensional space. In this location any satellites behind the aircraft are useless. ... This is essentially why in an aircraft we use external GPS antennas at all. In your car we don't care. Any position fix is typically good enough. Not so in an airplane.

I would recommend moving them - particularly if you intend to do GPS LPV approaches.
 
I have three Garmin gps antennas under my engine cowling. Two non-WAAS antennas (for my 430 non-WAAS unit?s) and one WAAS antenna for my 335 ads-b unit. The distance between all three units is about 16 inches. The non-WAAS antennas have been positioned there for about eight years and the WAAS antenna for two years. Have not had any trouble at all with the antennas (knot on wood). Just remember while separation distance is somewhat flexible the minimum length of your WAAS antenna wire is not. Unfortunately, I do not remember that minimum length you need to have but you can call Steinair to confirm it. Just loop the wire under your panel.

Good luck.
 
Fine

They?re find under cowl. You?ll still have way more satellites than required. I?ve put them all over the airplane and never had any issues. Usually tracking the max 24 satellites even partially buried. I?ve also had antennas next to each other without affect
 
Garmin multiple GPS antenna install min distance

From the Garmin install manual for IFR installations:

"no closer than 12 inches (center to center, 9 inches minimum) from other antennas, including passive antennas such as another GPS antenna or XM antenna. This will minimize the effects of shadowing at 5° elevation angles."

"4. To maintain a constant gain pattern and limit degradation by the windscreen, avoid mounting the antenna closer than 3 inches from the windscreen.
5. For multiple GPS installations, the antennas should not be mounted in a straight line from the front to the rear of the fuselage. Also varying the mounting location will help minimize any aircraft shading by the wings or tail section (in a particular azimuth, when one antenna is blocked the other antenna may have a clear view)."
 
Last edited:
I had absolutely wonderful satellite reception with my Garmin G3X antennas mounted on a shelf under the cowling on my RV-10 with the GTN-650 GPS antenna mounted on the cabin cover. I will be putting the G3X antennas again under the cowling of my -9A along with the GTN-650 GPS antenna under there. 6'-6" is the minimum GPS antenna cable length for the 650.
 
My G3x and 650 antennas almost touch each other and work just fine. No feedback on Dynon but I don?t think these passive antennas are very sensitive to other passive antennas. YMMV
 
Inside Right Wingtip

Dynon GPS-2020 and Garmin GA-57X. The top edge of each antenna just barely clears the inside top of the wingtip. No issues with either one.

FRPoRbc4l65CuUSDqeuHFweGWD1oUaYJzjXqFlFsb5Rk_QLGzSkme0ZBBk8I-csmRngFxag3yMql9g58zrTSN3RXuJStRZxvWYE8KEFqZdr_FdDwkFzMxSnUr1xiBxNsC-wzBKlnROn360vd-B--EwERMrldLaFI_N11L2PR6YfkV78sAHm9WUsLSAk_e9DsAcrcbfLxuHX0ej6ntG9qagauNI5h5JlrRJ6aM8kThwJzXyYy7MAVqV0JnBtEbGna-Aip0UTViBGSacXNKI98sqrg8xgO3UnZu_V2z48v_7_bEO5yrVvKS6aJqmQRKF8eQfdQJoeqaJT-YR0qO5YaSS69crtyNUGEfQIEPri7qcQZdL0EjDAS0q9ZeNldB-SKkHsz8la4KjJCwHWU-D1v9TVSg1TQ5m_aEFbtQfGqOohFtJHoS4aVUu7JJg9DeJHRbnlHp0h3W4NoapA4ighCd_14LnDJkEsE3fISAMc9A0Divz6KNJM5z-91B894XCn5arC8YZ6G3UoQbr7jy4yI7cjt-WLfVMMlKJ-WTB0cBwjLEnm3B3CK9qxyIl01TCoC2pgPxn6wz_vyBIhWMS3Ri5-lEH_SwtIDtKuqU5PW8hhrPGdEvbTVO88aQJlopsWF0Ik8SteWoFeogWlqBlkN0945=w1024-no
 
My G3x and 650 antennas almost touch each other and work just fine. No feedback on Dynon but I don?t think these passive antennas are very sensitive to other passive antennas. YMMV

Actually GPS antennas are not passive, they have amplifiers and associated electronics in them. Many instances of the old GA35 antennas going bad and taking out nearby GPS's. Mount them next to each other at your own risk, I will never mount an IFR antenna next to another GPS antenna.
 
I have a Garmin 296 GPS antenna and uAvionix SkyFYX-EXT ADS-B antenna mounted side-by-side on a shelf under the fiberglass cowling on my RV-12. No problems ? excellent GPS reception and dozens of good PAPR reports.

23tnxbl.png
 
Actually GPS antennas are not passive, they have amplifiers and associated electronics in them. Many instances of the old GA35 antennas going bad and taking out nearby GPS's. Mount them next to each other at your own risk, I will never mount an IFR antenna next to another GPS antenna.

Note that the Dynon GPS antenna doesn't even have a co-ax cable going to it. All of the processing electronics are within the antenna and it has a digital output.
 
Back
Top