Examples disclosed herein relate to an antenna calibration method for a beam steering radar. A first set of input voltages is determined for a plurality of phase shifters coupled to a plurality of antenna elements in an antenna array in the beam steering radar, the voltages to control phases of signals for transmission by the antenna array. A first set of input voltages is applied to the antenna array. Radiating signals resulting from the first set of input voltages are measured. Voltage and phase values for the plurality of phase shifters are iteratively optimized to determine voltage and phase value pairs that result in a desired gain for the antenna array. The voltage and phase value pairs are stored in a look-up-table in the beam steering radar.