A high-capacity cable widely used in audio, video and data applications. Commonly called "coax" (pronounced "co-axe"), coaxial cable is used for hooking up TVs to antennas, cable and digital satellite service. It is also used for cable modems and various digital interfaces such as S/PDIF.

Strong and flexible, coaxial cable contains an insulated solid or stranded wire in the center, surrounded by insulation. The insulation is wrapped with an aluminum or copper sheath, which can be a wrapped foil or a braided wire fabric. The sheath serves as the ground line and interference shield. All of this is wrapped in a plastic cover, which may have a fire-safe Teflon coating.

There Are Many Types
Often similar in appearance, there are several types of coaxial cables. Typically with impedances of 50 or 75 Ohms, cables have different outside diameters and maximum capacities for operating voltage. Cables are also rated for signal loss (attenuation in dBs per 100 feet). Coaxial cable types are designated with an RG (radio grade) prefix such as RG-6. Following are the most common coaxial cables; however, there are many more types in use.

           Impedance  Core  Layers
           Range in   Dia.   in     Typical
 Type      Ohms       (mm)  Sheath  Purpose

 RG-6        75-76    1.0   two   TV, cable, sat
 RG-6 Quad   75-76    1.0   four  TV, cable, sat

 RG-58       50-53.5  0.9   one   TV, thin Ethernet

 RG-59       73-75    0.81  one   TV, cable, S/PDIF
 RG-59 Quad  73-75    0.81  four  TV, cable, S/PDIF