What does an SWR reading of 4:1 indicate?

Standing Wave Ratio (SWR) represents how well the impedance of a load (the antenna) matches the impedance of the transmission line. A perfect match is 1:1, meaning all available power is transferred smoothly to the load. An SWR of 4:1 is a relatively high value. This reading indicates that a large portion of the transmitted power is failing to radiate and is instead reflecting back toward the transmitter. This reflection is directly caused by an impedance mismatch between the feed line and the antenna. Options suggesting a specific loss or gain in decibels (dB) are incorrect. SWR measures the matching and reflection characteristics of the system, not absolute signal gain or the inherent attenuation of the feed line.