VSWR

VSWR (Voltage Standing Wave Ratio) is an indicator that shows the reflection characteristics of signals in coaxial cables. To understand VSWR, let’s first explain the relationship between standing waves and reflection waves.
What are standing waves?
A standing wave is a wave formed by the interference between a traveling wave (input signal) and a reflected wave (signal reflected back from the cable’s terminus) within a coaxial cable. This interference causes waves to reinforce each other at certain points and cancel each other out at others. The voltage at points where waves reinforce each other is called the maximum voltage (Vmax) of the standing wave, and the voltage at points where waves cancel each other out is called the minimum voltage (Vmin) of the standing wave.
VSWR is the ratio of the maximum voltage (Vmax) to the minimum voltage (Vmin) of the standing wave (Standing Wave) and is expressed by the following equation.

VSWR is an important metric in RF circuit design. Understanding VSWR enables the suppression of signal return loss and the realization of efficient transmission.