Coaxial cable, or coax, is a type of cable that has an inner conductor surrounded by a tubular insulating layer, surrounded by a tubular conducting shield. Many coaxial cables also have an insulating outer sheath or jacket. The term coaxial comes from the inner conductor and the outer shield sharing a geometric axis.

Coaxial cable is used as a transmission line for radio frequency signals. Its applications include:

• ISDN Telecommunication line
• Analogue CCTV system
• SMATV system
• Satelite TV

Knowing how to install and terminate coax cable properly is critical to achieving impedance matching. Knowledge and selection of the best available materials greatly increases efficiency.