The term reflection coefficient is used in physics and electrical engineering when wave propagation in a medium containing discontinuities is considered. In general, the reflection coefficient describes the amplitude of a reflected wave relative to an incident wave. The reflection coefficient is closely related to the transmission coefficient.

Different specialties have different applications for the term.

Telcommunication

In telecommunication, the term reflection coefficient (RC) has the following meanings:

1. 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. This is typically represented with a Γ (capital gamma).

Note 1: The reflection coefficient may also be established using other field or circuit quantities.

Note 2: The reflection coefficient is given by the equations below, where Z ₁ 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:

The reflection coefficient is displayed graphically using a Smith chart.

Source: from Federal Standard 1037C in support of MIL-STD-188

Seismology

See: reflection seismology

Optics

See: Fresnel Reflection Coefficients