A method for automatically tuning an impedance matrix of an apparatus presented, at a given frequency, by m ports of the apparatus, where m is an integer greater than or equal to 2, each of said m ports being referred to as "user port", the apparatus having said m user ports and n other ports, where n is an integer greater than or equal to 2, each of said n other ports being referred to as "target port", said impedance matrix being referred to as "the impedance matrix presented by the user ports", the apparatus allowing, at said given frequency, a transfer of power from the user ports to the target ports, the method comprising the steps of: successively applying, by a multiple-output signal processing device, m different excitations to the user ports, wherein each of output ports of the external device is coupled to one and only one of the user ports, and each of the user ports is coupled to one and only one of the output ports of the multiple-output signal processing device; informing a signal processor of the apparatus, by the multiple output signal processing device, that one or more of the m excitations have been applied; delivering one or more "sensor output signals", each of the sensor output signals being determined by one or more electrical variables sensed at one of the user ports; estimating q real quantities depending on the impedance matrix presented by the user ports, where q is an integer greater than or equal to m, using the sensor output signals obtained for the m or more different excitations applied successively to the user ports; using said q real quantities depending on the impedance matrix presented by the user ports, to obtain "tuning control signals"; adjusting the impedance matrix presented by the user ports using a multiple-input-port and multiple-output-port tuning unit, the multiple-input-port and multiple-output-port tuning unit comprising p adjustable impedance devices, where p is an integer greater than or equal to 2m, each of the adjustable impedance devices having a reactance at said given frequency, the reactance of any one of the adjustable impedance devices having an influence on the impedance matrix presented by the user ports, the reactance of any one of the adjustable impedance devices being adjustable by electrical means; applying each of the tuning control signals to one or more of the adjustable impedance devices, the reactance of each of the adjustable impedance devices being determined by one or more of the tuning control signals. successively applying, by a multiple-output signal processing device, m different excitations to the user ports, wherein each of output ports of the external device is coupled to one and only one of the user ports, and each of the user ports is coupled to one and only one of the output ports of the multiple-output signal processing device; informing a signal processor of the apparatus, by the multiple output signal processing device, that one or more of the m excitations have been applied; delivering one or more "sensor output signals", each of the sensor output signals being determined by one or more electrical variables sensed at one of the user ports; estimating q real quantities depending on the impedance matrix presented by the user ports, where q is an integer greater than or equal to m, using the sensor output signals obtained for the m or more different excitations applied successively to the user ports; using said q real quantities depending on the impedance matrix presented by the user ports, to obtain "tuning control signals"; adjusting the impedance matrix presented by the user ports using a multiple-input-port and multiple-output-port tuning unit, the multiple-input-port and multiple-output-port tuning unit comprising p adjustable impedance devices, where p is an integer greater than or equal to 2m, each of the adjustable impedance devices having a reactance at said given frequency, the reactance of any one of the adjustable impedance devices having an influence on the impedance matrix presented by the user ports, the reactance of any one of the adjustable impedance devices being adjustable by electrical means; applying each of the tuning control signals to one or more of the adjustable impedance devices, the reactance of each of the adjustable impedance devices being determined by one or more of the tuning control signals.