Antenna tuning apparatus for a multiport antenna array

An apparatus for tuning n antennas, where n is an integer greater than or equal to four, the n antennas operating in a given frequency band, the apparatus comprising:

• n antenna ports, the antenna ports seeing, at a frequency in the given frequency band, an impedance matrix referred to as the impedance matrix seen by the antenna ports, the impedance matrix seen by the antenna ports being a complex matrix of size n×n;
• m user ports, where m is an integer greater than or equal to three, the user ports presenting, at said frequency in the given frequency band, an impedance matrix referred to as the impedance matrix presented by the user ports, the impedance matrix presented by the user ports being a complex matrix of size m×m;
• and
• 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 frequency in the given frequency band, the reactance of any one of the adjustable impedance devices being adjustable by electrical means, the apparatus for tuning n antennas being such that there exists a diagonal impedance matrix referred to as the given diagonal impedance matrix, the given diagonal impedance matrix being such that, if the impedance matrix seen by the antenna ports is equal to the given diagonal impedance matrix, then (a) the reactance of any one of the adjustable impedance devices has an influence on the impedance matrix presented by the user ports, and (b) the reactance of at least one of the adjustable impedance devices has an influence on at least one non-diagonal entry of the impedance matrix presented by the user ports.

An apparatus for tuning n antennas, where n is an integer greater than or equal to two, the n antennas operating in a given frequency band, the apparatus comprising:

• n antenna ports;
• m user ports, where m is an integer greater than or equal to two;
• n adjustable impedance devices each having a first terminal coupled to a first terminal of one of the antenna ports and each having a second terminal coupled to a second terminal of said one of the antenna ports;
• n(n−1)/2 devices each having a first terminal coupled to one of the antenna ports and each having a second terminal coupled to one of the antenna ports which is different from the antenna port to which the first terminal is coupled, and each being selected from a group consisting of an adjustable impedance device and a passive linear two-terminal circuit element;
• m adjustable impedance devices each having a first terminal coupled to a first terminal of one of the user ports and each having a second terminal coupled to a second terminal of said one of the user ports;
• and
• m(m−1)/2 devices each having a first terminal coupled to one of the user ports and each having a second terminal coupled to one of the user ports which is different from the user port to which the first terminal is coupled, and each being selected from a group consisting of an adjustable impedance device and a passive linear two-terminal circuit element;
• wherein each of the adjustable impedance devices has a reactance at a frequency in the given frequency band, the reactance of any one of the adjustable impedance devices being adjustable by electrical means.

An apparatus for tuning n antennas, where n is an integer greater than or equal to two, the n antennas operating in a given frequency band, the apparatus comprising:

• n antenna ports;
• n user ports;
• n adjustable impedance devices each having a first terminal coupled to a first terminal of one of the antenna ports and each having a second terminal coupled to a second terminal of said one of the antenna ports;
• n adjustable impedance devices each having a first terminal coupled to a first terminal of one of the user ports and each having a second terminal coupled to a second terminal of said one of the user ports;
• and
• n windings each having a first terminal coupled to one of the antenna ports and each having a second terminal coupled to one of the user ports;
• wherein mutual induction exists between two or more of the windings;
• and
• wherein each of the adjustable impedance devices has a reactance at a frequency in the given frequency band, the reactance of any one of the adjustable impedance devices being adjustable by electrical means.