What does an SWR reading of 4:1 indicate?

An SWR (Standing Wave Ratio) reading of 4:1 indicates an impedance mismatch. The SWR measurement reflects how well the antenna’s impedance matches that of the transmission line and the transmitter. A lower ratio, like 1:1, signifies a good match with minimal reflected power, while higher values indicate increasing levels of reflection due to a poor match between the antenna and the feedline.

In this case, a 4:1 SWR means that for every 4 units of forward power sent to the antenna, 1 unit is reflected back, suggesting that the impedance of the antenna differs significantly from the characteristic impedance of the transmission line, often 50 ohms. This mismatch can lead to inefficient transmission and potential damage to the transmitter.