A base station includes a processing unit, a plurality of radio frequency units, a plurality of antenna units, a control unit and an adjustment unit. The processing unit generates a baseband signal and provides a control strategy. The radio frequency units receive the baseband signal to generate a plurality of radio frequency signals. The antenna units transmit a plurality of output signals. The control unit receives the control strategy and generates a plurality of control signals according to the control strategy. The adjustment unit receives the radio frequency signals and the control signals, switches the connection of RF paths with high-gain or low-gain between the radio frequency units and the antenna units and adjusts gains of the radio frequency signals according to the control signals, so as to generate the output signals.