On Sunday, December 31, 2017 at 5:33:39 AM UTC-8, wrote:
AC 43.13B 308d says you need a backing ground plane.
But I didn't see any special details for CF versus other composites?

The big note in plain English and bolt text staring you in the face in AC 43.13-2B: "NOTE: Carbon Fiber composite material, while conductive has not been found to be adequate as a ground plane."