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
Coaxial Cable
Coax uses two wires. The inner wire is the primary conductor. The ground wire is an aluminum or copper sheath that surrounds the insulation of the primary conductor and also serves as a shield against external interference.
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