a method is provided for use in calibrating a plurality of antennas comprised in an antenna array and wherein the antenna array comprises at least one gain control circuitry . the method comprises : transmitting one or more pre - defined signals by at least one antenna comprised in the antenna array ; receiving at one or more of the antennas comprised in the antenna array , a signal derived from a corresponding pre - defined signal transmitted by the at least one antenna ; and for each of the one or more antennas , detecting whether there is any difference between the corresponding one or more pre - defined signals transmitted thereto and the respective one or more signals received thereat , and if in the affirmative , applying the detected differences in a process of calibrating the one or more antennas comprised in the antenna array , and wherein the process of calibrating the one or more antennas comprised in the antenna array comprises a step of estimating a ratio of complex transmission coefficients for at least two states of the at least one gain control circuitry .