Comm antenna distance from pilot? Becker flex antenna?

Help,

Anyone have any good info on how far a comm antenna should be from the pilot?

My current antenna in mounted in the rudder, and the coaxial is cracked inside the rudder.

Trying to find another place to mount an antenna without going external and without cutting into the rudder.

This is in a Silent-IN, and there is carbon in the tail from about the back third of the wing all the way back.

The area around the pilot is glass, and also there is a possibility of mounting behind my seat back.

Considering using the Becker flexible antenna that appears to be made from coaxial. Anyone have any experience with this antenna?

Thanks

Kevin
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