Coaxial cable is a cable that has two concentric conductors, and the conductor and shield share the same axis. The most common coaxial cable consists of a copper wire conductor isolated by an insulating material. On the outside of the inner insulating material is another layer of ring conductor and its insulator, and then the entire cable is covered by a sheath of polyvinyl chloride or Teflon material. .
Coaxial cable is used by TV companies between TV users and community antennas, and can also be used by telephone companies, and is also widely used in corporate intranets and Ethernet. Many cables or many pairs of cables can be placed in the same insulation, plus an amplifier that can transmit signals far away.