Patent ID: 8143517

Claim:
A coaxial cable, comprising: a heat treated extra-fine copper alloy twisted wire comprising seven copper alloy wires each of which comprises a wire diameter of 0.010 to 0.025 mm, and 1 to 3 weight % of silver (Ag) and a balance consisting of copper and an inevitable impurity, the twisted wire further comprising a tensile strength of not less than 850 MPa, and an electrical conductivity of not less than 85% IACS; a foamed insulation formed on an outer circumference of the extra-fine copper alloy twisted wire; an outer conductor comprising a plurality of conductor wires wound on an outer circumference of the foamed insulation along a longitudinal direction thereof in a spiral form; and a jacket layer formed on a surface of the outer conductor, wherein the extra-fine copper alloy twisted wire comprises a lowering rate in electric resistance of not less than 6% after the heat treatment and a lowering rate in tensile strength of not more than 20% after the heat treatment.