A coaxial cable is a type of electrical cable that features a central conductor surrounded by an insulating dielectric layer and an outer conductor that acts as a shield. The two conductors share the same geometric axis, hence the term coaxial.
Coaxial cables, often referred to simply as coax, are engineered to transmit high-frequency electrical signals with minimal interference and signal loss. The construction consists of four primary layers: a central conductor (typically made of solid or stranded copper), a dielectric insulator, a metallic shield (usually braided copper or aluminum foil), and an outer protective jacket. This unique design ensures consistent impedance and provides effective shielding from electromagnetic interference (EMI) and radio frequency interference (RFI), making coaxial cables highly reliable in electrically noisy environments.
When the outer conductor or shield is grounded, the inner conductor is protected from external signal disruptions, maintaining clarity and precision in transmission. The dielectric material between the conductors is equally important, as it maintains consistent spacing and influences the cable’s impedance, commonly 50 or 75 ohms, depending on the intended application.
In commercial and industrial systems, coaxial cables are essential for transmitting data, video, and radio frequency signals across long distances. They are widely used in security surveillance (CCTV), broadcast networks, broadband distribution, and AV systems, where stable and high-quality signal transfer is critical. Their durability and resistance to external interference make them ideal for large-scale infrastructure and building integration.
Commonly governed by NEC (National Electrical Code) and UL (Underwriters Laboratories) standards, which define construction requirements, flame ratings, and safety compliance for coaxial cabling systems. Performance standards may also be influenced by IEEE and TIA for data and communication applications.
Coaxial cable was first patented in 1880 by English engineer Oliver Heaviside but gained commercial prominence in the early 20th century with advancements in radio, television, and telecommunications. Its ability to carry wide bandwidth signals without significant loss made it a cornerstone technology for analog and digital signal transmission. Over time, improved shielding materials and dielectric compounds have expanded its use in modern high-frequency and broadband systems.