Coaxial cable (figure 1-18) is defined as two concentric wires, cylindrical in shape, separated by a dielectric of some type. One wire is the center conductor and the other is the outer conductor.

These conductors are covered by a protective jacket. The protective jacket is then covered by an outer protective armor.

Figure 1-18. - Coaxial cable.

Coaxial cables are used as transmission lines and are constructed to provide protection against outside signal interference.