Coaxial cables

They are ideally suitable for the transmission of high frequency signals. Coaxial cable is capable of achieving high data transmission speeds over long distances. For this reason, it is generally used for cable television, radio stations, closed circuit television (CCTV), video equipment, broadband and Ethernet applications. Coaxial cables or coax cables have the particularity of having two concentric conductors: a central one called the nucleus (also called core or live core), in charge of transporting information, and another exterior one that has a tubular appearance called mesh, armouring or braid, which serves as an earth and current return (Coaxial means that two or more shapes share a common axis). The central conductor can be made of a single copper wire (rigid) or of several twisted wires (flexible), while the outer conductor can be a braided mesh, a helical foil or a corrugated tube. Between both conductors there is an insulating layer (dielectric) that separates both conductors (preventing contact), and the whole set is covered in turn with another layer (called the outer sheath) to protect the whole set from external effects. Coaxial cables generally have a characteristic impedance of 50, 75 or 93 Ω. The characteristic impedance is the ratio of applied voltage/current absorbed by a coaxial cable of infinite length.