Roof Shark Fin

[M80]

The Viano 639 has one. With the ceiling out I can see there are 2 wires out of it.
1 is connected and is the GPS.
T'other, a Fakra, isn't connected, so I wonder if these things are dual purpose, being additionally for FM or possible DAB.

FM is via a windscreen antenna, but I've tried for better alternatives and so far failed.

If dual purpose I would have expected it to be an amplified signal, but there is no obvious power to it. But I suppose the power could be through the centre core of the coax??

Any ideas on what the unused wire might be for?

 

[Blobcat]

The Viano 639 has one. With the ceiling out I can see there are 2 wires out of it.
1 is connected and is the GPS.
T'other, a Fakra, isn't connected, so I wonder if these things are dual purpose, being additionally for FM or possible DAB.

FM is via a windscreen antenna, but I've tried for better alternatives and so far failed.

If dual purpose I would have expected it to be an amplified signal, but there is no obvious power to it. But I suppose the power could be through the centre core of the coax??

Any ideas on what the unused wire might be for?

Power is generally centre of coax - if head unit doesn’t provide power you can get antenna adapters that take a power feed from the iso connector on the back of the head unit and feed it up the coax.

 

[M80]

Power is generally centre of coax - if head unit doesn’t provide power you can get antenna adapters that take a power feed from the iso connector on the back of the head unit and feed it up the coax.

Thanks,
the GPS side isn't going to need power.
If the other side is FM, DAB, or even digital telly is a possible, then I guess the power will be via the centre core as you say.

My question is what is the 2nd side of this shark fin likely to be. If it is DAB then I'll put the effort in to making it serviceable.
The screen antenna is useable, but I hope could be better. The roof top antennas I've tried are a failure so far.

The van is with pre wired passenger entertainment wiring, so this 2nd side may be for DTV, that tbh I'm not fussed about.