A comparison of the power accepted to the power reflected back from the system, generally with respect to a 50 Ohm line impedance. A VSWR of 1.0 is 100% of power accepted by the antenna, a VSWR of 1.5 is 97%, a VSWR of 2.0 is 89%.
Voltage Standing Wave Ratio. The ratio of maximum voltage to minimum voltage along the line. Expresses the degree of match between the transmission line and the terminating element (antenna). When VSWR is 1:1 the match is perfect, a VSWR of 1.5:1 corresponds to 96% power efficiency.
Voltage Standing Wave Ratio - A measure of the uniformity of impedance along a transmission line, or the quality of the impedance match between a line and the source or load.