triaxial cable
Triaxial cables are concentrically constructed coaxial cables which, in contrast to two-core coaxial cables, consist of three concentrically arranged conductors.
The inner conductor is surrounded by an insulating dielectric, which is surrounded by the first shield. The first shield is surrounded with an insulating dielectric, a second shield and the cable sheath. The thickness and material of the dielectric are the determining factors for the impedance of the triax cable.