Coaxial cable is a type of wire and signal transmission line, usually made of four layers of material: the innermost layer is a conductive copper wire, the outer layer of the wire is surrounded by a layer of plastic (used as an insulator or dielectric), and the outer layer of the insulation is also a thin mesh of conductive material (usually copper or alloy), and the outer layer of the conductive material is used as the outer skin.
Coaxial cables can be used for the transmission of analog and digital signals, and are suitable for various applications, including the most important ones such as cable television transmission, long-distance telephone transmission, short distance connections between computer systems, and local area networks. Coaxial cable, as a means of transmitting television signals to thousands of households, has developed rapidly, which is cable television. A cable television system can load dozens or even hundreds of television channels, and its transmission range can reach tens of kilometers. Coaxial cables have long been an important component of long-distance telephone networks. Today, it faces increasingly fierce competition from fiber optics, ground microwaves, and satellites