Characteristic impedance

The characteristic impedance is the input resistance of an infinitely long wire or a wire terminated with the characteristic impedance.

The impedance is a quantity that represents the ratio of electrical to magnetic waves of a data line. The characteristic impedance is of decisive importance for the compatibility of individual components of a data transmission system. All elements of a data connection must have the same characteristic impedance (e.g. transmitter output, connectors, cables, receiver input). The characteristic impedance is calculated from the inner diameter of the outer conductor, the outer diameter of the inner conductor and the dielectric constant of the insulation.