Coaxial cable is a type of cable which consists of a copper inner conductor, surrounded by a dielectric insulator which is often plastic, this is then cover with a woven copper shield all of which is under a plastic outer sheath or jacket. The term coaxial comes from the fact the both the inner conductor and the shield are on the same axis. Coaxial cables were first developed in the 1880s to be an efficient transmitter of radio frequency signals.
Coax cables are used for a host of different applications which include lines which connect radio transmitters and receivers with the antennas; they are used in computer networking and for the distribution of cable television signals. A primary advantage of coaxial video cable is that it can be installed close to metal objects without suffering from power loss or electromagnetic interference. These benefits are derived from the construction of the cable as the signal exists only between the inner conductor and the shield.
The inner conductor of coaxial cable is either solid or stranded copper or steel wire which has been copper coated. This central conductor is then fully enclosed in an insulation material. The metallic shield is woven copper strands, depending on the cable the woven shield can be one up to four layers including metallic tapes. The shield is grounded and voltage runs through the center conductor which carries signals. The idea of coaxial video cable is to keep the signals inside the cable and to keep electronic and magnetic signals outside the envelope from getting in and causing unwanted signal interference and distortion. Coaxial cables are ideally suited for carrying very weak signals that cannot tolerate any environmental interference.
When coaxial video cable is used to receive television signals, it is the cable that brings the signal to the home through an overhead or underground service drop. The standard cable that is used is RG-6 which connects to the set with a type F connector. The cable television provider will bring the signal to a distribution box which is mounted externally. Built in coaxial wiring which runs through the walls of the building then carry the signal from the distribution box to jacks which are located in specific rooms in the building. The televisions are then connected to the jacks with a coaxial jumper of a made up length.
RG59 and RG6 and 6/U coaxial video cables for use with CATV and SATV are available from Domain.
