So, like all 8(A) builders, I am having to decide between many bad options for the ELT antenna. Looking over past threads, I would summarize the most popular options as under the empennage fairing, or in the passenger armrest. Both of these seem like they have the antenna hidden behind a lot of metal, and wouldn't transmit very well. I have also seen the mid cabin brace mount, but that seems to be lacking a proper ground plane, and I am planning on putting a camera there.
Another option would on the bottom which has a great ground plane, and would be perfect if the plane ends up on its back, as 3/10 of the 8A accidents I find in the NTSB archives did. However, if you stay upright, it would easily be scraped off by brush or flattened under the fuse, turning into nothing at all.
My I think original idea, is to take a quarter wave 406Mhz antenna, which by my calculations is about 7 inches long, and put it behind the passenger's head like so:
This could be a homemade rod antenna, or a commercial ducky type like this:
http://www.wpsantennas.com/exc406bnx-antenexcenturion406-420mhzbncmalecoveredtufduckantenna.aspx
Good points: I have measured, this will not hit the canopy either open or closed. It is likely to survive anything the occupants survive. Has a decent (tho not perfect) ground plane. This meets the ELT manufacturor requirements for 406Mhz, but probably not for 121.5. They do keep saying they want to stop listening on 121.5.
According to the manual, I must use an approved antenna, and this is not on the (very short) list. However, I think it would actually work better than the approved antenna in most accident scenarios. So, meeting the spirit if not the letter of the law.
Wanted to get some other opinions before I start drilling holes.
Another option would on the bottom which has a great ground plane, and would be perfect if the plane ends up on its back, as 3/10 of the 8A accidents I find in the NTSB archives did. However, if you stay upright, it would easily be scraped off by brush or flattened under the fuse, turning into nothing at all.
My I think original idea, is to take a quarter wave 406Mhz antenna, which by my calculations is about 7 inches long, and put it behind the passenger's head like so:
This could be a homemade rod antenna, or a commercial ducky type like this:
http://www.wpsantennas.com/exc406bnx-antenexcenturion406-420mhzbncmalecoveredtufduckantenna.aspx
Good points: I have measured, this will not hit the canopy either open or closed. It is likely to survive anything the occupants survive. Has a decent (tho not perfect) ground plane. This meets the ELT manufacturor requirements for 406Mhz, but probably not for 121.5. They do keep saying they want to stop listening on 121.5.
According to the manual, I must use an approved antenna, and this is not on the (very short) list. However, I think it would actually work better than the approved antenna in most accident scenarios. So, meeting the spirit if not the letter of the law.
Wanted to get some other opinions before I start drilling holes.