A Phased Array Antenna, PAA, communication system comprising: an array of antenna elements (A i); at least one digital beamforming circuitry (31t/32r) associated with at least one of said antenna elements (A i); memory; and a control unit configured and operable to record on-line signature of at least one antenna element of said array; said on-line signature being indicative of signals received by one or more other antenna elements (A i) of said array, in response to transmission of one or more predetermined signals from said at least one antenna element during operation of the system, compare said on-line signature of the at least one antenna element with at least some portion of respective off-line signature of said at least one antenna element, which is stored in said memory; said off-line signature is indicative of signals received by said one or more other antenna elements (A i) while the system is under idealized operational conditions, response to transmission of said one or more predetermined signals from said at least one antenna element (A i) of said array and receipt of the transmitted signals by said one or more other antenna elements of said array, generate calibration data based on the comparison between said on-line and off-line signatures, and modify parameters of one or more elements in said at least one digital beamforming circuitry (31t/32r) based on said calibration data to compensate flaws induced in the system due to artifacts in analog or digital portions of the system. an array of antenna elements (A i); at least one digital beamforming circuitry (31t/32r) associated with at least one of said antenna elements (A i); memory; and a control unit configured and operable to record on-line signature of at least one antenna element of said array; said on-line signature being indicative of signals received by one or more other antenna elements (A i) of said array, in response to transmission of one or more predetermined signals from said at least one antenna element during operation of the system, compare said on-line signature of the at least one antenna element with at least some portion of respective off-line signature of said at least one antenna element, which is stored in said memory; said off-line signature is indicative of signals received by said one or more other antenna elements (A i) while the system is under idealized operational conditions, response to transmission of said one or more predetermined signals from said at least one antenna element (A i) of said array and receipt of the transmitted signals by said one or more other antenna elements of said array, generate calibration data based on the comparison between said on-line and off-line signatures, and modify parameters of one or more elements in said at least one digital beamforming circuitry (31t/32r) based on said calibration data to compensate flaws induced in the system due to artifacts in analog or digital portions of the system. record on-line signature of at least one antenna element of said array; said on-line signature being indicative of signals received by one or more other antenna elements (A i) of said array, in response to transmission of one or more predetermined signals from said at least one antenna element during operation of the system, compare said on-line signature of the at least one antenna element with at least some portion of respective off-line signature of said at least one antenna element, which is stored in said memory; said off-line signature is indicative of signals received by said one or more other antenna elements (A i) while the system is under idealized operational conditions, response to transmission of said one or more predetermined signals from said at least one antenna element (A i) of said array and receipt of the transmitted signals by said one or more other antenna elements of said array, generate calibration data based on the comparison between said on-line and off-line signatures, and modify parameters of one or more elements in said at least one digital beamforming circuitry (31t/32r) based on said calibration data to compensate flaws induced in the system due to artifacts in analog or digital portions of the system.