ELT Antenna: vertical or horizontal?

[ceslaw]

Glad to see you have a solution!

I have used copper foil in other applications where a ground system was required and have found after several years the adhesive can fail. You may want to consider a mechanical connection to assure it will be in place a long time from now. Perhaps a small aluminum plate with a couple rivets near the top? If the copper foil detaches and ends up touching the antenna shorting it will put it out of commission.

Locating the antenna base about 24" from the top of the extended baggage would be about ideal. That would leave room for a quarter wave radial should one chose that option to tune the 121.5 frequency and make it easier to access. I agree that trying to reach it in the upper location suggested by CC through that little access would require the services of a talented skinny six year old with long arms.

[Daveembry]

Good catch. I think maybe I'll put some epoxy or even methacrylate to the last 1/2" or so of the foil to be sure it doesn't come loose. Thanks!

Glad to see you have a solution!

I have used copper foil in other applications where a ground system was required and have found after several years the adhesive can fail. You may want to consider a mechanical connection to assure it will be in place a long time from now. Perhaps a small aluminum plate with a couple rivets near the top? If the copper foil detaches and ends up touching the antenna shorting it will put it out of commission.

Locating the antenna base about 24" from the top of the extended baggage would be about ideal. That would leave room for a quarter wave radial should one chose that option to tune the 121.5 frequency and make it easier to access. I agree that trying to reach it in the upper location suggested by CC through that little access would require the services of a talented skinny six year old with long arms.

[Andy]

Good catch. I think maybe I'll put some epoxy or even methacrylate to the last 1/2" or so of the foil to be sure it doesn't come loose. Thanks!

If it is expected that the foil adhesive will degrade during the expected life of the aircraft, and if the conductive adhesive makes necessary contact with the rear wall of the baggage compartment, then this seems like a potential maintenance nightmare.

[Daveembry]

Yeah..... I wouldn't do it on any of your builds then Andy if I were you.

Really hard to move that little 5" inspection cover and take a look up to check (like you have to do at least every year anyway) and if it needs securing....takes 2 minutes. A real "potential maintenance nightmare". 🤦*♂️

Apparently you haven't even worked with methacrylate before either. It ain't coming loose.

If it is expected that the foil adhesive will degrade during the expected life of the aircraft, and if the conductive adhesive makes necessary contact with the rear wall of the baggage compartment, then this seems like a potential maintenance nightmare.

[Andy]

Yeah..... I wouldn't do it on any of your builds then Andy if I were you.

I have built quite a few antennas, some of my own design, and some adapting the designs of others. I have never used conductive adhesive as part of an antenna system. I'll yield to your expertise in this area.

[PBY Catalina]

The same installation as suggested by Dave, with thin strips of aluminum as support.
Test ok from the first try.

Thank you all!

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