What is the main function of an antenna tuner?

The primary role of an antenna tuner is to match the impedance of the transmitter to that of the antenna. When you transmit a signal, the transmitter and antenna need to have compatible impedance for efficient power transfer. If the impedances do not match, some of the power generated by the transmitter can be reflected back rather than being radiated as a signal, resulting in losses and potential damage to the equipment.

The antenna tuner accomplishes this by varying its own impedance to ensure that the combined system of the transmitter and antenna presents a matching load to the transmitter. This maximizes the effective radiated power (ERP) and improves the overall efficiency of the communication setup.

While adjusting transmission frequency or enhancing signal clarity might seem relevant, they are not the primary functions of an antenna tuner. Increasing power output is also not within its scope, as the tuner does not amplify the signal; it merely facilitates better matching between the transmitter and the antenna.