What Is Coaxial Cable Made of?

Several different coaxial cable designs are in common use. All use some configuration of the four basic components: central core, dielectric sheath, conductive shield and insulating jacket.

Central Core
In the most common coaxial cable, the inner core is a solid copper wire. Where flexibility is a priority, this may be a copper braid. The core of higher quality cables may be a silver-plated solid copper wire. In a few applications, a core of copper-plated steel wire has been used. For some high-power lines such as those feeding radio and TV antenna towers, the central core may be a hollow tube of copper or copper-plated aluminum.
Shielding
Common coaxial cable covers the dielectric sheath with a layer of braided copper or aluminum. This shield is grounded and prevents the signal from transmitting beyond that layer. The shielding also prevents external electromagnetic signals from reducing transmission quality. Solid tubes make more efficient shields but are more easily damaged. Sometimes a layer of coated aluminum foil is placed between the dielectric and the braid, or the foil is the only shield used. High power shields in hard-line coax may be copper, silver or even gold tubing.

June 21, 2011

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