koaksial

Koaksial, or coaxial, refers to a family of electrical cables designed to carry high-frequency signals with low loss and limited radiation. The defining geometry places a center conductor inside a cylindrical dielectric shield, which is itself enclosed by an outer conductor and an outer jacket. The arrangement confines the electromagnetic field to the space between the inner and outer conductors, minimizing interference from external sources and reducing cross-talk between adjacent cables.

A typical coaxial cable consists of four layers: a central conductor (solid wire or stranded), an insulating dielectric, an outer conductor (foil and/or braided shield), and an outer polymer jacket. Electrical impedance is determined by the conductor geometry and materials; common values are 50 ohms for RF communications and 75 ohms for video and broadband distribution. Coaxial cables support relatively wide bandwidth and are designed to minimize attenuation over their intended length.

Common variants include families such as RG-6 and RG-59 for consumer video and broadband, as well as specialized low-loss types for telecommunications and instrumentation. Coaxial cables are used in cable television, terrestrial and satellite radio links, broadband internet (DOCSIS), security cameras, and antenna feeds. They connect with a variety of connectors, including BNC, F-type, RCA, SMA, and N-type, depending on impedance, bandwidth, and environment.

Historically developed in the early 20th century to transmit radio signals with manageable interference, coaxial cables became a standard in many networks and broadcast systems. Standards and specifications are maintained by industry bodies such as IEC, ANSI, and IEEE, ensuring compatibility across devices and installations.