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Communications antenna recommendation?

N941WR

N941WR

Legacy Member
Since I'm putting my fuselage together I thought it might be easier to install the comm antenna now rather than later.

I will not have a VOR in my VFR ship so I am only looking for a belly mount comm antenna. (No desire to install a wing tip antenna.)

My RV will be a -9 (Yes, a tail dragger) and I would like to hear recommendations on which antenna I should go with and where I should place it.

Thanks for the help!
 
Best / easiest place is the bottom of the fuse, under the seat pans between the seat ribs. Easy access, easy install, and works great!

Cheers,
Stein.
 
On my -6A, I mounted the bent-whip COMM antenna directly in front of the main spar, right between my legs.

In the event of a radio failure, I can pull out my handheld (that I keep in the -6A gear weldment kluge), disconnect the BNC that's right down there in front of me, then connect the BNC-BNC patchcord from the handheld to the floor. The patchcord stays in the handheld case along with the headset adapter and PTT.

I had a radio failure a couple of years ago coming home from Las Cruces, and the gaggle flying with me couldn't tell I was on a handheld. Connecting your handheld to the bent-whip increases your range ten-fold.

Good luck! :) Rosie
 
Rosie, small world. I did the exact same thing (access to the antennae BNC connector under my left knee just fwd of the spar. It's such an easy 'backup'.
 
Placement of comm antenna on RV7-A

Doug and Rosie, I am also considering placing a bent whip comm antenna in the location you mentioned. I know nothing about these things, but I recall from somewhere that you can get interference (shadows) from metal objects, like the gear legs. Has this been a problem? In addition, where did you mount your transponder antenna? It would sure be handy to mount it in the same location on the co-pilot side. Any ideas?

Thanks,
Mike Morris
 
I put a bent whip and transponder (shark fin) on the bottom behind the baggage compartment. I located the shark fin just behind the baggage bulkhead on the left of center and the comm antenna to the right of center in front of the next bulkhead aft of the baggage bulkhead. Kinda staggered them. They seem to be just fine there. Make sure you make some doublers when you mount them. Just cut some 0.040 AL about 2" wider than the antennas and bolt them in when you mount the antennas. No need to rivet them. I just ran the cables up front under my carpet and made a small hole in the baggage closeout to the antennas.

Roberta
 
antenna location

I put the antenna (bent whip commant) in the same spot as Rosie and Doug. I worried about shadows cause I had heard the same thing. I have a garmin 250XL gps/com with only 5 watts of power. I have had no problems with shadows, interference, sending or receiving. works great and simple location to install and or service if needed. I located the transponder antenna just behind the seat on the passenger side. Jack
 
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Good advice

sundog04 said:
I recall from somewhere that you can get interference (shadows) from metal objects, like the gear legs. Has this been a problem?
Click to expand...
Worry not, follow the above suggestions. It works well. True any object can interfere with you radio antenna. It is hard avoiding being blocked by something on an airplane, but you are far enough away from the gear legs that it makes no practical difference. There may be an antenna placement that is slightly better theoretically but the belly locations mentioned look the best and are easy to install with short coax runs.

I like the fwd of spar idea for BNC connector access, good tip, did not think of that. The under seat pan is good also. Either way. Transponder centerline (or offset left or right) belly behind firewall is a good location. Some are mounting them in the engine compartment off the FAB (airbox), to apparently reduce drag, but the drag for a transponder antenna is worth about 0.10mph drag at 200mph.

I agree with not having the desire to install internal wing tip COM antenna, talk about interference (shadows) from metal objects. It may work good as it can, but good is relative term. Good might mean talking to the tower 5 miles away, but the external bent whip mounted as discussed will out perform the internal wing-tip antenna many times over. Cheers George
 
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Antenna Pics

Roberta, Doug and Rosie,

Any chance you could post a few pics of your antenna installations?

Thanks,

Pete
 
Here is where I mounted my Comm and Transponder antennas. The are staggered on either side of the centerline,

Roberta

comm9cr.jpg
 
I'm trying to find the best spots on a 4 for a bent whip and transponder antenna. I like the idea of having both in the center, somewhere ahead of the main spar. Any advice on this location would be great. I have no engine yet and am a little concerned about the exhaust roasting my antennas.

Steve Zicree
RV4 (with a working intercom!!)
 
Rule of thumb is to add the length of both antennas. This should be the minimum distance between them.
Mel...DAR
 
ouch

Thanks Mel,

I already messed up, I got the anntenas (radio monday per stein) no instructions, what happens if they are 18 inches side by side.. put the comm on the left in front of the spar, and the transponder on the the right.. its the little post type.. I really don't want cover that hole :( I have the bent whip.. facing
back.. didn't think about it till I read these post
1/2 a day too late on the question..

Danny..
 
Turn that frown upside down

godspeed said:
Thanks Mel, I already messed up, I got the antennas (radio monday per stein) no instructions, what happens if they are 18 inches side by side.. I really don't want cover that hole :( I have the bent whip.. facing back.. didn't think about it till I read these post
1/2 a day too late on the question.. Danny..
Click to expand...
:( Turn that frown up side down :) , 18" will be fine. I had them that close on my RV4. In fact you meets Mel requirement, since the whip is about 20" and the transponder is a few inches. The RF EMF will not worry about a few inches. George
 
Antennas aren't part of the airframe

You can really screw up your communication radio system if you don't do a little independent study before installing it or copy a working system. The straight or bent antennas will work just about anywhere on our metal airplanes for the ranges we use so copying an installation that is working is a good way to go. The landing gear is not going to bother your ability to communicate. The only situation that I have seen that causes some communication problem is when the comm antennas are on the bottom of the plane (airplane and ground plane), you are trying to communicate with the tower while sitting on the ground, their antenna is above the airplane and the radiation from your antenna is completely blocked by the aircraft structure in the direction of the tower receiving antenna. Usually you can turn the plane or switch to #2 comm (assuming a different antenna position) and overcome this glitch.

I was an old Air Force radio mechanic (thank you tax payers for sending me to Scott AFB for 37 weeks of training - it helped me start a career) and I would never install an antenna so that the coax connector is exposed on the floor of the crew compartment. I installed two bent whips under the seat pan between the outer two seat ribs for the pilot and passenger on my RV-6A. The transponder "spike" is near the center of the fuselage and all three are in a straight line across the fuselage of my RV-6A and there is no detectable interference or communication problems. The marker beacon antenna is on the bottom of the fuselage in the second bay behind the baggage compartment, the "V" VOR/LOC/GS antenna is on the top of the vertical stabilizer with most of the center puck under the VS cap, and the GPS antenna is on top of the fuselage aft of the sliding canopy, and the ELT antenna is in the baggage compartment. The only one that I think could have been done better is placing the GPS antenna "on the dash" under the windshield. When I installed the roll servo after flying for a year or so, the RV-6A installation called for it to go where I had the left comm antenna so I moved the antenna one bay toward the center. This was after the plane was painted. There was no detectable degradation of performance from the move.

Bob Axsom
 
locations for an 8A

I have been reading this thread with interest since I am nearing the point of decision regarding ant placement on my 8A. I will be using two comm radios, two transpoder ant, one for the transponder and another for my monroy traffic detector, and the IFR stuff.

Does anyone have a proven configuration for this setup in an 8 or 8A? I like the tip of having the BNC connector available for the handheld backup.

Any information, especially pics, would be appreciated.

Tony
 
Adding another Comm & Antenna...

And have been considering the combo antenna from comant that has com and GPS antenna built into one unit. I already have the GPS on top which theoreticaly would also be the best place for the comm antenna. Not sure how it would look though (but I don't think it would look bad). Anybody ever use this combo antenna or mount their comm antenna on top? As always I want the plane to look good but from the begining I've chosen function over looks so thinking this may be the best option to achieve both. Thoughts/suggestions appreciated!
 
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