Characteristic Impedance of Electrical Transmission Lines

the ratio of voltage to current at any point on a line along which electromagnetic waves are propagating. It is the resistance offered by the line to a traveling voltage wave. In a line of infinite or finite length, with impedance equal to the characteristic impedance, there will be no reflection of electromagnetic waves or formation of standing waves. In this case the line passes to the load virtually all of the energy from the generator (without losses). The characteristic impedance is

where L and C are the inductance and capacitance of the line per unit length.