VSWR stands for Voltage Standing Wave Ratio, and it is a measure of how efficiently radio-frequency power is transmitted from a power source, through a transmission line, and into the load. It is a measure of the impedance matching between the radio or transmission line and antenna, indicating the amount of power reflected back to the transmitter when a signal is transmitted through an antenna. A high VSWR indicates that there are problems with the antenna and/or transmission line, as a large amount of energy is being reflected back instead of being radiated by the antenna. The VSWR is defined as the ratio of maximum to minimum voltage on a transmission line. A perfect match is 1:1, and a complete mismatch, i.e., a short or open circuit, is ∞:1. The higher the VSWR, the bigger the standing wave, the less efficient the transfer of power is, and the greater the difference in impedance between the source and the load. VSWR can be calculated if we already know the impedances of the source and load. Overall, setting VSWR specifications is a difficult but necessary task for antenna engineers to create reliable antennas that perform to their full potential.