Abstract: An automatic array calibration apparatus which is capable of periodically calibrating beamforming offsets using internally generated calibration and test signals. The apparatus preferably includes a calibration signal generating unit which generates a continuous wave calibration signal which is input into a receiving channel as the input signal. I/Q signals are obtained from reception data channels which have been provided with the calibration signal. The apparatus also includes a loop back operation in which test signals are injected in transmission data channels, and are prepared for transmission at a transmission unit. The transmission signal is looped back to the receiving unit and I/Q signals are obtained from reception data channels supplied with the transmission signals.