Significance of the standing wave ratio

rtk

What is the significance of the standing wave ratio?

VivekK

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!! ?

rtk

It looks like we need to have smaller SWR. What is the lowest range physically possible?

VivekK

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. 

Hope that addressed your concern! ?

rtk

Thank you for your explanation :-)