Antenna Installation?

I have purchased an ICOM A210 COMM transceiver and Garmin GTX327 radar transponder. I also bought a CI-122 bent whip COMM antenna and a CI-101 "ball on a stick" transponder antenna. I plan to install both on the belly of my RV6. Where have others successfully installed these or simillar antennae? Also any wire run issues to be aware of or recommendations?
Jim Sharkey
RV6 Tip-up O360-A1A FP
Getting there!!!

Usually belly between firewall & main spar

jsharkey said:

I have purchased an ICOM A210 COMM transceiver and Garmin GTX327 radar transponder. I also bought a CI-122 bent whip COMM antenna and a CI-101 "ball on a stick" transponder antenna. I plan to install both on the belly of my RV6. Where have others successfully installed these or similar antennae? Also any wire run issues to be aware of or recommendations? Jim Sharkey RV6 Tip-up O360-A1A FP Getting there!!!

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Do a archive search, lots of ideas. Spacing (ant to ant) of 3 feet or more is ideal, but often violated with no ill affect.

If you think about it the best place is both on the belly, just aft of the firewall, one on the left one on the right. Try and avoid putting it directly down stream & in-line of exhaust or too near exhaust pipes or gear legs. (Don't know what pipes you have.) Coax runs are minimal in this location. You will not get a full three feet antenna to antenna spacing, but I did this on my RV and there where no ill affect.

Another place is just fwd of the main spar carry through, belly, left, center or right. If you have it on the floor, fwd spar, under your knees, pilot side, you can make access to the BNC connector while seated. You can reach down and disconnect the coax in-flight and connect a short coax connector to a back-up hand held, if that appeals to you. This assumes your main radio dies and you have a back-up radio to use. Its one idea might turn you on. The coax runs are a little longer as you go aft. No big deal. Trying to go aft of the main spar has some access issues and not really needed in my opinion.

You may be able to put one antenna center-line just aft of firewall (battery allowing?) and the other center line just fwd of the main spar. (This assumes you don't have a single center line exhaust.) I can't picture the RV-6 floor structure, but the location of the antennas should be come apparent to you with a little thought. You can go any where on the heavy belly skin is my general advice.

You will get great performance from your modern radio and antenna, even if the antenna location is not perfect or ideal. Ideal is MAX distance from other antennas and other structure, gear legs & exhaust pipe. In general BELLY is best for in-flight Com (which is what you should want). Top of fuselage is generally best for ground communication. However a belly antenna will never give you a problem for ground com at smaller typical GA airports. Its not like you are flying out of JFK, ORD, DEN or LGA. Some times big terminals and long distances make belly antennas marginal.

Belly Antenna Location Best?

gmcjetpilot said:

In general BELLY is best for in-flight Com (which is what you should want). Top of fuselage is generally best for ground communication. However a belly antenna will never give you a problem for ground com at smaller typical GA airports. Its not like you are flying out of JFK, ORD, DEN or LGA. Some times big terminals and long distances make belly antennas marginal.

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Actually I have just completed some very unscientific testing on this subject

After having run stick and bent whip belly antennas for the last couple of years on my 7A, I decided to try one of the Comdat antennas on top that combine VHF/GPS. Well I'm here to tell you that range has improved noticably and communications are definately clearer over a longer range. Not a huge difference, but a noticable one.

So maybe belly antennas are better when you cruise at the flt levels but for the average altiudes I use (5-8K) the top of the fuselage appears to have the advantage in my case.

Does it look as good, the wife says it looks like a Bonanze now the kid noticed it immediately and said it looks way cool so the jury is still out on looks

Maybe the spam can builders actually have this figured out as virtually all factory airplanes have top mounted antennas!

Good work Walt

Walt said:

Maybe the spam can builders actually have this figured out as virtually all factory airplanes have top mounted antennas!

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Good for you testing. I suspect the gear legs have a major affect on the omnidirectional characteristics. Also being further from the engine and prop are pluses. There is no perfect because the wings and tail will still block a top mounted antenna. My theory is we are usually talking right off the nose or off the sides, and the antenna has a pretty straight shot on the top-back fuselage in the fwd & side directions, with no or less affect from the gear legs and prop. Speaking of Bonanzas, remember the antenna in front of the windshield.

The engineers take full sized plane and elevate them on a stand in an Anechoic chamber to test antennas. With such a small plane like the RV its almost impossible to find a perfect spot.