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Antenna locations

cdeerinck

Well Known Member
I'm having a rough time locating my antennae. I have my 2 Comm antennae in the typical location, wide as can be, just aft of the wing spar. I am using the Delta-Pop Bent Red Tails (http://www.deltapopaviation.com/VHF_Com_Antennas.html) for these.

I need to locate the two Delta-Pop Transponder/UAT antennae for my Transponder and ADSB. (http://www.deltapopaviation.com/Transponder_Antenna.html)

All of the avionics are Dynon Skyview, and the Dynon manual gives me the following guidelines: Transponder and ADSB at least 3' from Comm, and at least 2' from each other. In this case, I presume that means from the tip of the Red Tail, and not the base.

This is a picture of my rear fuselage:

xfxfno.jpg


Only two solutions seem possible:
1) On the centerline, one just aft of the bulkhead that is behind the battery tray, and the other 2' further back on the centerline.

2) Side by side, just in front of, and off to the sides of battery tray, but only 18" apart.

If I do option #1, I could put the transponder on the lower shelf (red arrow location), and the ADSB next to it (orange arrow), to keep the coax runs short. But my concern is their proximity to the ADAHRS unit(s), the ADAHRS (blue arrow), and a spot for an ADAHRS Backup location (green arrow) for future possible IFR. They would be just about 12" away from the ADAHRS, but separated by an aluminum shelf.

If I do option #2, I could put the transponder and ADSB on the side walls near the battery, keeping them just over 3' from the ADAHRS locations, but the antennae will be 6" closer than spec. Is there any fluff in the spec?

So, my question is, which of these options are better, or is their another option I haven't though of here?

Also, I know I am not supposed to kink RG-400, but can anyone tell me approximately how safe a radius is allowed?
 
I don't have any pictures handy, but put the ADS-B antenna just aft of your Autopilot Pitch Servo on centerline, and put the Transponder antenna underneath the Copilot's seat offset to the left.
 
Transponder antenna just outboard of center line and about as far aft as the rear stick. ADS-B antenna aft of the rear baggage compartment. For the Dynon system mount the ADS-B receiver there as well and run a single four conductor shielded wire to the receiver.

Carl
 
Carl and Jeff,

Putting one antenna at the rear stick or under the co-pilot seat puts it only about a foot from the tip of the Comm antenna. Why would that not be a problem? :confused:
 
tuff crowd

This question seems to get a lot of builder. The space under the 8,4 and 3 is not much to work with. I can only speak to where we put ours. I know what the book says about how far to put them away from each other, but consider the frequency that each works on and keep that in mind while you install them. Also do they send or transmit or both with regard to their placement close to each other. We put the Com. antenna in the left foot well of the back seat, as far forward and to the left as we felt it would not get in the way. The Trans. antenna went in the right foot well as far back and to the right as it could go to be serviceable and out of the way. The ADS-B antenna went under an approx. 6" inspection cover put in the rear baggage floor just to the left of the push-rod. The Marker Beacon antenna went on the centerline of the tail-boom just behind the bulked that holds the bell crank, just behind your battery. The VOR antenna went on top of the V.S. just like you see factory airplanes, on a hand made bracket set to three rivets on each side of the upper rib. You just cut a slot out of the fiberglass cap to let the antenna come out both side. OH, I liked it when we turned them forward like a Moony ( nice look ). The GPS antennas got put on top of the front baggage skin and in the back on the hat rack inside the canopy.
We would use splitters for the NAV. and COM. antennas. Don't know if this helps but it is what we came up with after hitting the same wall. They all work very well and have no overlap with frequency problems.
Yours, R.E.A. III #80888
 
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You might want to pose the question on the Dynon forum but I believe the distance apart has to do with the mounting location / ground plane.
 
I am interested in input on this as well.

I have CI122 COM 1 and COM 2 like most behind the spar as far outboard as possible. An archer Model 1 NAV antenna in the right wing tip. GPS antennas (Garmin and Dynon) on a tray under the cowl. Need to find a good location for TED antennas for ADSB and transponder. I could go with the Comant CI-105 to reduce drag or AS has 11-13830 which is less expensive. I am thinking about in the wing near the inboard inspection cover, one on the right and one on the left. I also need a good place for the OAT probe.

Anyone have experience with the AS 11-13830? Any suggestions are welcome.
 
This question seems to get a lot of builder. The space under the 8,4 and 3 is not much to work with. I can only speak to where we put ours. I know what the book says about how far to put them away from each other, but consider the frequency that each works on and keep that in mind while you install them. Also do they send or transmit or both with regard to their placement close to each other. We put the Com. antenna in the left foot well of the back seat, as far forward and to the left as we felt it would not get in the way. The Trans. antenna went in the right foot well as far back and to the right as it could go to be serviceable and out of the way. The ADS-B antenna went under an approx. 6" inspection cover put in the rear baggage floor just to the left of the push-rod. The Marker Beacon antenna went on the centerline of the tail-boom just behind the bulked that holds the bell crank, just behind your battery. The VOR antenna went on top of the V.S. just like you see factory airplanes, on a hand made bracket set to three rivets on each side of the upper rib. You just cut a slot out of the fiberglass cap to let the antenna come out both side. OH, I liked it when we turned them forward like a Moony ( nice look ). The GPS antennas got put on top of the front baggage skin and in the back on the hat rack inside the canopy.
We would use splitters for the NAV. and COM. antennas. Don't know if this helps but it is what we came up with after hitting the same wall. They all work very well and have no overlap with frequency problems.
Yours, R.E.A. III #80888

Perhaps you did not mean "use splitters for comm antennas". Splitters only work for reception - the most common case being two NAV radios on one NAV antenna.

Carl
 
I mounted the ADS-B aft of the pitch servo and the transponder antenna just left of center and aft of the of the copilot seat in the rear baggage compartment. I also placed the single red tip comm antenna at the right foot well. I am good on the distances if it is supposed to be measured from the center point BNC connectors but I am short between the comm and transponder antenna if it is from the red tip. Didn't think about that. Does anyone know definitively?
 
Perhaps you did not mean "use splitters for comm antennas". Splitters only work for reception - the most common case being two NAV radios on one NAV antenna.

Carl

upps, yes got in to big of a hurry on that sorry.
Too go to one of the other question he had here. I see the position of wanting to place the antennas in the wing tips. Yes we looked at that for a long time as well, and there are a lot that do so and it works fine if you wish it that way. We found that if you put the antennas in the main airframe you would have less service work in the long run and use less RG-400 with sorter wire runs except for the VOR antenna. This is a personal choice, but one that is made based on years of service work and trying to cut down on time spent doing repairs. Hope this helps, Yours as always. R.E.A. III #80888
 
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