# Significance of the standing wave ratio

Pune, India Forum Coordinator Posts: 0
What is the significance of the standing wave ratio?
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• Pune, IndiaPosts: 137Forum Coordinator

Standing Wave Ratio (SWR) is a measure of the impedance matching in a transmission line and it is expressed as a function of reflection coefficient. When the load impedance is not matched with the characteristic impedance of the transmission line then the reflected waves arise and will form a standing wave pattern because of the interaction with the forward waves.

Hope this helps!! ?

• Pune, IndiaPosts: 167Forum Coordinator
It looks like we need to have smaller SWR. What is the lowest range physically possible?
• Pune, IndiaPosts: 137Forum Coordinator

Hello @rtk ,

Voltage SWR can be given mathematically in terms of reflection coefficient as VSWR = (1+|Г|)/(1-|Г|), where |Г| denotes the magnitude of reflection coefficient. So, the range of VSWR depends upon the range of reflection coefficient. Theoretically, SWR ranges between 1 and Infinity and it is a nonlinear function. For an optimum design, the SWR value should be close to 1. Higher values of SWR denote more reflected waves which in turn can damage the source.