HTC has said it, it's in one of their statements or videos posted somewhere here.
Those white lines on the back are plastic insulators for the two antennas, same material is used on the sides, and has to be around all sides of the two antennas.
Those white lines on the back are plastic insulators for the two antennas, same material is used on the sides, and has to be around all sides of the two antennas.



. I think it's something called AGC where it cuts out/lowers the volume of certain frequencies if they go over a certain level.