The ratio of the amplitude of the reflected wave and the amplitude of the incident wave. 2. At a discontinuity in a transmission line, the complex ratio of the electric field strength of the reflected wave to that of the incident wave. Note 1: The reflection coefficient may also be established using other field or circuit quantities. Note 2: The reflection coefficient is given by where Z1 is the impedance toward the source, Z 2 is the impedance toward the load, the vertical bars designate absolute magnitude, and SWR is the standing wave ratio.