What is standing wave ratio (SWR)?

Standing Wave Ratio (SWR) is a critical measurement in radio transmission that indicates the impedance match between your transmitter, the transmission line, and the antenna load. When the impedance of the antenna perfectly matches the feed line (typically 50 ohms), all the radio frequency (RF) power travels to the antenna and is radiated. If there is a mismatch, some of the RF power reflects back down the feed line toward the transmitter. The interaction between the forward and reflected waves creates 'standing waves.' SWR does not measure amplifier power, transmitter efficiency, or the quality of a station's ground connection. A 1:1 SWR means a perfect match with zero reflected power, while higher ratios indicate a poorer match and reduced efficiency.