Posted for "FredE" <fwegli@astound.net>:

 Bill,
 Although I am an electronic engineer by training, these comments are only my
 $.25 worth from actual experience.
 The belly of my LIV has the transponder and a bent Whip comm antenna on it.
 They were both mounted directly to the carbon skin with no further attempt
 at providing additional ground plane. I have had no problems with
 transponder identification or communication and, of course, the installation
 was very easy. FWIW
Fred Egli LIV N1228E