FEP compositions are provided that provide foam insulation in coaxial
cable that surpasses the return loss obtained when PFA is used to make
the foamed insulation, one composition comprising a blend of
tetrafluoroethylene/hexafluoropropylene copolymers, one of said
copolymers exhibiting a strip force of at least about 3 lbf (13.3 N) and
another of said copolymers exhibiting a strip force no greater than about
2.5 lbf (11.1 N), said blend exhibiting a strip force of at least about 3
lbf (13.3 N), each said strip force being the force necessary to break
adhesion between conductor and said one of said copolymers, said another
of said copolymers, and said blend, respectively, and another composition
comprising tetrafluoroethylene/hexafluoropropylene copolymer having an
MFR of no greater than about 16 g/10 min and containing --CF.sub.3 end
groups and an effective amount of wire affinity end groups to exhibit a
strip force of at least about 3 lbf (13.3 N), said strip force being the
force necessary to break adhesion between conductor and said copolymer,
the coaxial cable exhibiting an average return loss of no greater than
about -26 dB at 800 MHz to 3 GHz and having a void content of about 20 to
65% and (b) forming an outer conductor over said foamed insulation.