Standing wave ratio
= Standing wave ratio
{title2=$\mathrm{SWR}=(1+|\Gamma|)/(1-|\Gamma|)$}
{wiki}
On a uniform lossless <transmission line>, incident and reflected sinusoidal waves give <voltage> maxima $|V^+|(1+|\Gamma|)$ and minima $|V^+|(1-|\Gamma|)$. Their ratio is the <voltage> <standing wave ratio>, $(1+|\Gamma|)/(1-|\Gamma|)$, where $\Gamma$ is the voltage-wave <reflection coefficient>. A matched termination gives one, while perfect reflection gives an infinite ratio. These expressions assume a common real <characteristic impedance> and no propagation attenuation between the compared extrema.