Antenna tuners are devices used in radio communication systems to match the impedance of the transmitter or receiver to the impedance of the antenna. This matching is necessary to ensure maximum power transfer and efficient signal transmission. Tuners work by adjusting the electrical length of the antenna, typically through the use of inductors and capacitors. By altering the impedance, tuners can compensate for variations in antenna characteristics caused by factors such as frequency, weather conditions, or nearby objects. They are commonly used in amateur radio stations, where they allow operators to optimize their antenna systems for different frequencies and operating conditions.