Foamed coaxial cable with high precision and method of fabricating same

A foamed coaxial cable with high precision according to the present invention comprises: an internal conductor twisted with a plurality of electrically conductive wires: a foamed insulator with its low dielectric constant made of a porous tape body formed on the outer periphery of this internal conductor; an external conductor made of a number of electrically conductive thin wires braided on the outer periphery of this foamed insulator; and an outer sheath made of a resin having heat resistance formed on the outer periphery of this external insulator, wherein the precision of external diameter of the internal conductor is 4/1000mm or less, the precision of external diameter size of the foamed insulator is ± 0.02mm, the insulator is formed in a completely circular shape, the precision of external diameter size of the external conductor is ± 2%, the external conductor is formed in a completely circular shape, and the precision of characteristic impedance value between the internal conductor and the external con