Reflection coefficient
From Wikipedia, the free encyclopedia
The reflection coefficient is used in physics and electrical engineering when wave propagation in a medium containing discontinuities is considered. A reflection coefficient describes either the amplitude or the intensity 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.
Contents |
[edit] Telecommunications
In telecommunications, the reflection coefficient is the ratio of the amplitude of the reflected wave to the amplitude of the incident wave. In particular, at a discontinuity in a transmission line, it is the complex ratio of the electric field strength of the reflected wave to that of the incident wave. This is typically represented with a <math>\Gamma</math> (capital gamma).
The reflection coefficient may also be established using other field or circuit quantities.
The reflection coefficient is given by the equations below, where <math>Z_1</math> is the impedance toward the source, <math>Z_2</math> is the impedance toward the load:
- <math>\Gamma = {Z_2 - Z_1 \over Z_2 + Z_1}</math>
The absolute magnitude of the reflection coefficient (designated by vertical bars) can be calculated from the standing wave ratio, <math>SWR</math>:
- <math>| \Gamma | = {SWR - 1 \over SWR + 1}</math>
The reflection coefficient is displayed graphically using a Smith chart.
Source: from Federal Standard 1037C in support of MIL-STD-188
[edit] Seismology
[edit] Optics
In optics, both intensity and amplitude reflection coefficients are used. Typically, the former are represented by a capital R, while the latter are represented by a lower-case r.
[edit] References
Books
- Bogatin, Eric (2004). Signal Integrity - Simplified. Upper Saddle River, New Jersey: Pearson Education, Inc.. ISBN 0-13-066946-6. Figure 8-2 and Eqn. 8-1 Pg. 279es:Coeficiente de reflexión
