Abstract: Apparatus for calibrating a phased array antenna having a plurality of active modules and a test manifold. An RF antenna, which is both a transmitting and receiving antenna is positioned at a far field range from the antenna to be calibrated. A receiver is connected to the output of the far field receiving antenna and the output of the test manifold of the antenna to be calibrated for the transmit calibration and a transmitter is connected to the far field transmitting antenna and the test manifold for a receive calibration, a command phase and amplitude for each steering angle of each module of the antenna being calibrated. The phase and amplitude data from the test manifold is compared with the phase and amplitude data of the far field range to obtain an error signal, and the error signal is combined with the command amplitude and phase iteratively until the error signal is minimized for each module of the antenna.