Designed by English engineer and mathematician Oliver Heaviside, Coaxial Cable (coax) designs have been around since 1880. When manufactured these cables are constructed with an inner conductor surrounded by a tubular insulating layer, enclosed by a tubular conducting shield, certain types also include an insulated outer sheath or jacket. This detailed construction of coax cables provides an interference-free transmission path for high-frequency electrical signals.

 

Each element of the design of a Coaxial cable affects its size, attenuation, frequency performance, power handling capabilities, strength, flexibility, and pricing. Different constructions of the inner conductor, Overall Diameter (OD) and dielectric materials, produce different values for ohms, maximum voltage, and impedance.

 

The thin center conductor is composed of solid or stranded (more flexible) braided copper insulated with a dielectric layer. The inner conductors are sometimes constructed of silver plated copper for high-frequency performance. Solid polyethylene (PE) and Teflon (PTFE) are common choices for insulating these cables. Shielding the dielectric is either metal foil or a braided copper mesh. To supply enhanced shielding performance certain cables are manufactured with double layer shields, such as two braids, a common choice is a thin foil shield covered by a wire braid. Higher priced cables may invest in more than two shields like quad shields that have alternating layers of foil and braid for shielding purposes. The shielding choices are chosen depending on the flexibility needs of the application. This construction is then covered with an insulated jacket. The shield layers are grounded to the connectors on the ends of the coax cable which helps enhance the signals and eliminate interference.