Method and apparatus for automatic tuning of an impedance matrix, and radio transmitter using this apparatus

An apparatus for automatically tuning an impedance matrix 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 apparatus comprising:

• at least m sensing units, each of the sensing units delivering one or more sensing unit output signals, each of the sensing unit output signals being mainly determined by one or more electrical variables;
• a signal processing unit, the signal processing unit 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 sensing unit output signals obtained for m excitations applied to the user ports, one and only one of the excitations being applied to each of the user ports, each of the excitations having a complex envelope, the complex envelopes of them excitations being linearly independent in the set of complex functions of one real variable, regarded as a vector space over the field of complex numbers, the signal processing unit delivering a tuning instruction as a function of said q real quantities depending on the impedance matrix presented by the user ports;
• 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 m, the p adjustable impedance devices being referred to as the adjustable impedance devices of the tuning unit and being such that, at said given frequency, each of the adjustable impedance devices of the tuning unit has a reactance, the reactance of any one of the adjustable impedance devices of the tuning unit having an influence on the impedance matrix presented by the user ports, the reactance of any one of the adjustable impedance devices of the tuning unit being adjustable by electrical means;
• and
• a tuning control unit, the tuning control unit receiving the tuning instruction from the signal processing unit, the tuning control unit delivering tuning control signals to the multiple-input-port and multiple-output-port tuning unit, the tuning control signals being determined as a function of the tuning instruction, the reactance of each of the adjustable impedance devices of the tuning unit being mainly determined by one or more of the tuning control signals.

A transmitter for radio communication with a plurality of antennas in a given frequency band, comprising:

• n antenna output ports, where n is an integer greater than or equal to 2;
• m power amplifiers, where m is an integer greater than or equal to 2, each of the power amplifiers having an output port, each of the power amplifiers being able to deliver a power in said given frequency band, a part of said power being transferred to the antenna output ports, the output ports of the power amplifiers seeing, at a frequency in said given frequency band, an impedance matrix referred to as the impedance matrix seen by the output ports of the power amplifiers;
• at least m sensing units, each of the sensing units delivering one or more sensing unit output signals, each of the sensing unit output signals being mainly determined by one or more electrical variables;
• a signal processing unit, the signal processing unit estimating q real quantities depending on the impedance matrix seen by the output ports of the power amplifiers, where q is an integer greater than or equal torn, using the sensing unit output signals obtained for m excitations applied by the power amplifiers at the output ports of the power amplifiers, one and only one of the excitations being applied at each of the output ports of the power amplifiers, each of the excitations having a complex envelope, the complex envelopes of the m excitations being linearly independent in the set of complex functions of one real variable, regarded as a vector space over the field of complex numbers, the signal processing unit delivering a tuning instruction as a function of said q real quantities depending on the impedance matrix seen by the output ports of the power amplifiers;
• 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 m, the p adjustable impedance devices being referred to as the adjustable impedance devices of the tuning unit and being such that, at said frequency in said given frequency band, each of the adjustable impedance devices of the tuning unit has a reactance, the reactance of any one of the adjustable impedance devices of the tuning unit having an influence on the impedance matrix seen by the output ports of the power amplifiers, the reactance of any one of the adjustable impedance devices of the tuning unit being adjustable by electrical means;
• and
• a tuning control unit, the tuning control unit receiving the tuning instruction from the signal processing unit, the tuning control unit delivering tuning control signals to the multiple-input-port and multiple-output-port tuning unit, the tuning control signals being determined as a function of the tuning instruction, the reactance of each of the adjustable impedance devices of the tuning unit being mainly determined by one or more of the tuning control signals.