What is the main use of an SWR bridge?

The primary function of an SWR bridge is to measure the standing wave ratio (SWR) in an antenna system. SWR is crucial for assessing how effectively an antenna transmits and receives radio frequency (RF) signals. It represents the ratio of the power reflected from the antenna to the power transmitted into the antenna.

When the SWR is low, it indicates that the majority of the transmitted power is being radiated by the antenna, while a high SWR indicates that a significant portion of the power is being reflected back, which can lead to inefficiencies and potential damage to the transmitter. An SWR bridge provides a way for operators to monitor this ratio, allowing them to adjust their setup for optimal performance.

The other options pertain to functions that are not associated with an SWR bridge. Amplifying a transmitted signal involves different equipment, as does automatically tuning an antenna or switching between sending and receiving modes. Therefore, understanding the measurement capabilities of an SWR bridge is critical for ensuring that an amateur radio station operates effectively and safely.