The VSWR (Voltage Standing Wave Ratio) is defined as the ratio between the incident and reflected wave in an RF component or DAS/IBS system. It determines the efficiency of power transmission from a source to the load through a transmission line. The minimum value of VSWR can be 1:1, which is an ideal condition where 100% of power from source is absorbed by the load. However, in real-world applications, VSWR is rarely found to be 1:1 and systems are designed to keep the VSWR as close to unity as possible.
In radio engineering and telecommunications, SWR is a measure of impedance matching of loads to the characteristic impedance of a transmission line or waveguide. Impedance mismatches result in standing waves along the transmission line, and SWR is defined as the ratio of the partial standing wave's amplitude at an antinode (maximum) to the amplitude at a node (minimum) along the line.
In an ideal RF transmission system, the impedance of source and transmission line must be perfectly matched with the impedance of the connected load. VSWR can be defined as the numerical measure of how well the impedances of these integral components are matched.
