Com Antenna Location

[Steve W]

Has anyone mounted their com antenna, with success, on the top of the .032 aluminum inner wing skin?
thanks

[Bdflies]

Yes. My Comm antenna is on the right side, inboard wing skin. Works great.

Bill

[Ed.Meyer]

We put ours on the upper faring between wing and fuselage. Put a doubler under it to improve strength. Works good.

[Steve W]

Thanks for the replies. Good to hear it works well at that location. Was concerned about only having a bit more than half a circle of ground plane.

[Ed.Meyer]

I wondered about ground plane too. Doesn't seem to be a problem though.

[Ray Strickland]

I mounted one on the left and one on the right. Work great.

[Ed Welfred]

I was told that reducing the ground plane on one side reduces the range in that particular direction in propotion to the amount of reduction of the ground plane.
Ed

[Ray Strickland]

I am certainly not an antenna expert, but since the skin of each wing is electrically bonded to the fuselage tubing, doesn't that make the entire airframe the ground plane?

[whee]

Hey Steve, You decide to not use the AAE internal antenna? My home made internal antenna seemed to work acceptably but I changed to a bent whip while trying to isolate a com issue. The antenna wasn't the issue.

I was looking forward to hear how yours worked.

[Steve W]

Hi Whee
Chickened out. Was trying to put my com and ELT Antennas in the rear and couldn’t get a good test from the ELT.
I just don’t want any reason to have to dig into completed parts after it’s gone from the shop.

[robcaldwell]

For what's it worth, I installed my ELT antenna inside the covered fuselage and it works astonishingly well! How do I know? While on a business trip in Manhattan, NY I received a phone call from the local Charlotte Civil Air Patrol. They received a notification from the Air Force Rescue Coordination Center (AFRCC) that a ELT beacon was transmitting from my garage. Keep in mind that my ELT was in a 3 story all brick building, in the back of a garage, inside a covered fuselage. Turns out the switch on my ACK 406mhz ELT was faulty. ACK replaced the ELT entirely.

(In this pic I have since included a 4" ground plane which was in place at the time of my offense)

[Ray Strickland]

I guess that should settle that!

[Steve W]

Yea that's impressive for sure. I have a Kannad 406 with a build in GPS and internal antenna. It wouldn't give me a positive test indicating the external antenna was at fault. 6" ground plane and grounded to the fuselage and mounted about the same place. I thought of trying to use the back baggage aluminum sheet as a vertical ground plane. I took a large piece of aluminum and mounted the antenna to it, placed the sheet horizontal and got a positive test. Turned it vertical and it failed the next one. Lord knows what position it would be in after a tumble in the bushes but it needs the external antenna function to receive and include the GPS data with the output. I might just say screw it and put it on a larger ground plane, 18-20", and mount it internally behind the baggage compartment.
If you look at the reviews of the ELT on Spruce's website, a guy took his out of his plane and set it on a table outside the aircraft in an all steel building. He got the same call from SAR about 10 minutes later. Instead of turning it off, he turned it on. Signal was received with the internal antenna inside a steel building. Thus the purchase.

[Bcone1381]

I appreciate the feedback on the ELT antenna location. I'm also looking for feedback on the AAE style antenna that asked about by Whee in post #8.

http://www.advancedaircraft.com

The ELT antenna is a different animal than a COM antenna. The ELT transmits on 406 mhz and its antenna is shorter. A com radio uses between 118 and 140 mhz. The steel fuselage may produce more diffaculty for the internal antenna on a COM radio due to the longer wave length that a COM radio uses. So if you use a copper foil antenna that is mounted inside a steel fuselage behind the baggage area, please give some feedback.

[Steve W]

Only have the ELT antenna in the back now and most likely will mount an external one on the wing for the com. I was thinking of trying the AAE antenna flat on the bottom against he fabric behind the gear along one of the stringers before I drill any holes in any wing skins but won't have any results of this until next spring. I also have foil insulation on the bottom and uncertain if this would affect it. The foil would be backing the antenna.

[Bcone1381]

From what I recall reading, the Comm antenna position needs to have a vertical component to it.

[Ray Strickland]

Yep. Com signals are vertically polarized