Editing Reflection coefficient (section)

=== Standing  wave ratio ===
{{Main|Standing  wave ratio}}
The [[standing wave ratio]] (SWR) is determined solely by the ''magnitude'' of the reflection coefficient:

:<math> SWR =  {1+| \Gamma |   \over 1- | \Gamma | } .</math>

Along a lossless transmission line of characteristic impedance ''Z''<sub>0</sub>, the SWR signifies the ratio of the voltage (or current) maxima to minima (or what it would be if the transmission line were long enough to produce them). The above calculation assumes that  <math>\Gamma</math> has been calculated using ''Z''<sub>0</sub> as the reference impedance. Since it uses only the ''magnitude'' of <math>\Gamma</math>, the SWR intentionally ignores the specific value of the load impedance ''Z<sub>L</sub>'' responsible for it, but only the magnitude of the resulting [[impedance mismatch]]. That SWR remains the same wherever measured along a transmission line (looking towards the load) since the addition of a transmission line length to a load <math>Z_L</math> only changes the phase, not magnitude of <math>\Gamma</math>. While having a one-to-one correspondence with reflection coefficient, SWR is the most commonly used figure of merit in describing the mismatch affecting a [[radio antenna]] or antenna system. It is most often [[SWR meter|measured]] at the transmitter side of a transmission line, but having, as explained, the same value as would be measured at the antenna (load) itself.