An apparatus for performing calibration of an antenna array having a plurality of antennas including at least a first antenna and a second antenna. The apparatus includes a global navigation satellite system receiver configured to measure a first phase of a first signal received by the first antenna from a satellite and a second phase of a second signal received by the second antenna from the satellite. The apparatus also includes at least one processor configured to receive the first phase and the second phase from the global navigation satellite system receiver and to operate in a calibration mode to determine a difference between the first and second phases.