Coaxial cable (or "coax") is the most common cable used for transmitting video signals. The name "coaxial" refers to the common axis of the two conductors
A coaxial cable has a solid copper or copper-clad-steel centre conductor surrounded by a non-conductive dielectric insulating material. The dielectric is surrounded by foil shield/s and/or copper braid/s which form the outer conductor and also shield against electromagnetic interference (EMI). The outer conductor/shield is encased in a PVC jacket.
Most coaxial cables for video applications have a nominal impedance of 75 ohms. Their differing electrical and physical characteristics make it important to select the correct type of cable to suit the application.
The three most commonly used coaxial cable types for video applications are RG59, RG6 and RG11.
RG 59 is available with either solid copper or copper-clad-steel centre conductor. It's suitable for basic analog TV antenna feeds in residential applications and for basic CCTV systems over short cable runs. The copper-clad-steel type has high tensile strength and should be used when terminating the cable with F-Type connectors
RG 6 is used for digital TV antenna cabling and for TV antenna cabling. It is also used for the distribution of Cable TV (CATV) and Satellite TV (SATV) in residential or commercial premises. It features a copper-clad-steel inner conductor. Single-shield, dual-shield and tri-shield versions of RG6 are available but do not provide adequate EMI shielding.
RG11 is used for the same applications as RG6 for either backbone cabling or for long distribution runs. It features a copper-clad-steel inner conductor.