A digitally controlled phase shifter for an antenna, comprising: a coupler extending between input and output ports (16, 18); first and second digitally tunable capacitance circuitry coupled to opposite ends of the coupler, each first and second digitally tunable capacitance circuitry comprising a digitally tunable capacitance; control circuitry comprising at least one processor and at least one memory including computer program code, wherein the at least one memory and the computer program code are configured to, upon execution by the at least one processor, cause the control circuitry to vary a capacitance provided by the digitally tunable capacitance of at least one of the first and second digitally tunable capacitance circuitry in order to modify a phase shift provided by the digitally controlled phase shifter, characterized in that the at least one memory and the computer program code are further configured to, upon execution by the at least one processor, cause the control circuitry to: prior to varying the capacitance, cause a control signal to be provided to the digitally tunable capacitance of the at least one of the first and second digitally tunable capacitance circuitry to establish an initial capacitance provided by the digitally tunable capacitance of the at least one of the first and second digitally tunable capacitance circuitry, vary the capacitance provided by the digitally tunable capacitance of the at least one of the first and second digitally tunable capacitance circuitry so as to have one or more candidate capacitances, and following varying the capacitance, determine a calibrated capacitance provided by the digitally tunable capacitance of the at least one of the first and second digitally tunable capacitance circuitry based upon a power provided by a radio to the antenna in response to the digitally tunable capacitance having the one or more candidate capacitances, wherein the calibrated capacitance is determined as the candidate capacitance at which the power provided by the radio to the antenna is greatest. a coupler extending between input and output ports (16, 18); first and second digitally tunable capacitance circuitry coupled to opposite ends of the coupler, each first and second digitally tunable capacitance circuitry comprising a digitally tunable capacitance; control circuitry comprising at least one processor and at least one memory including computer program code, wherein the at least one memory and the computer program code are configured to, upon execution by the at least one processor, cause the control circuitry to vary a capacitance provided by the digitally tunable capacitance of at least one of the first and second digitally tunable capacitance circuitry in order to modify a phase shift provided by the digitally controlled phase shifter, characterized in that the at least one memory and the computer program code are further configured to, upon execution by the at least one processor, cause the control circuitry to: prior to varying the capacitance, cause a control signal to be provided to the digitally tunable capacitance of the at least one of the first and second digitally tunable capacitance circuitry to establish an initial capacitance provided by the digitally tunable capacitance of the at least one of the first and second digitally tunable capacitance circuitry, vary the capacitance provided by the digitally tunable capacitance of the at least one of the first and second digitally tunable capacitance circuitry so as to have one or more candidate capacitances, and following varying the capacitance, determine a calibrated capacitance provided by the digitally tunable capacitance of the at least one of the first and second digitally tunable capacitance circuitry based upon a power provided by a radio to the antenna in response to the digitally tunable capacitance having the one or more candidate capacitances, wherein the calibrated capacitance is determined as the candidate capacitance at which the power provided by the radio to the antenna is greatest. prior to varying the capacitance, cause a control signal to be provided to the digitally tunable capacitance of the at least one of the first and second digitally tunable capacitance circuitry to establish an initial capacitance provided by the digitally tunable capacitance of the at least one of the first and second digitally tunable capacitance circuitry, vary the capacitance provided by the digitally tunable capacitance of the at least one of the first and second digitally tunable capacitance circuitry so as to have one or more candidate capacitances, and following varying the capacitance, determine a calibrated capacitance provided by the digitally tunable capacitance of the at least one of the first and second digitally tunable capacitance circuitry based upon a power provided by a radio to the antenna in response to the digitally tunable capacitance having the one or more candidate capacitances, wherein the calibrated capacitance is determined as the candidate capacitance at which the power provided by the radio to the antenna is greatest.