A communications apparatus. Multiple antennas are arranged to receive downlink signals and transmit uplink signals. A transceiver module is arranged to receive the downlink signals from the antennas and pass the uplink signals to an antenna selection device. The antenna selection device is coupled between the antennas and the transceiver module and arranged to receive the uplink signals to be transmitted from the transceiver module and dynamically pass the uplink signals to one of the antennas according to an antenna selection signal. A processor is arranged to receive the downlink signals from the transceiver module, calculate short-term signal qualities of the downlink signals and generate the antenna selection signal according to the short-term signal qualities.