Impedance

Electrical impedance is the complex property of an electrical circuit, or the components of a circuit, that opposes the flow of an alternating current. Ohms is the unit if measure. For a cable, its reading represents the total resistance that the cable presents to the electrical current passing through it. At low frequencies the impedance is largely a function of the conductor size, but at high frequencies, conductor size, insulation material and insulation thickness all affect the cable’s impedance. Matching impedance is very important. If the system is designed to be 100 Ohms, then the cable should match that impedance, otherwise error-producing reflections are created.