Methods and apparatus for matching an antenna

A method for matching an antenna of a radio device in which a standing wave ratio (SWR) value of a signal to be transmitted in a transmission path of the antenna is provided and a reactive pi-shaped matching circuit in the transmission path between a power amplifier of a transmitter and the antenna is adjusted to optimize a load impedance of the power amplifier, the matching circuit adjusted by a plurality of multiple-way switching elements located in transverse portions associated with the matching circuit, said method comprising:

• reading an information associated with an operating band that is in use;
• defining a trial array comprised of a subset of state combinations, said trial array being substantially smaller than a total array of a plurality of state combinations of said multiple-way switching elements, said act of defining utilizing at least a certain value of the transmitting power, said information associated with the operating band that is in use, and the SWR value;
• setting the switching elements of the matching circuit to each of the states associated with the subset of state combinations of the trial array;
• determining the SWR value of the signal to be transmitted in each state and determining the lowest one of the SWR values determined;
• setting the switches of the matching circuit to the state corresponding to the lowest one of the SWR values determined;
• and
• repeating the acts of reading, defining, determining and setting at a regular interval.

An apparatus for matching an antenna of a radio device, wherein a transmitter of the radio device comprises a power amplifier controllable by its output power and a transmission path from the power amplifier to the antenna, the apparatus comprising:

• a directional coupler in said transmission path to measure a level of a signal transmitted to the antenna and of a signal reflected from the antenna;
• apparatus configured to determine a standing wave ratio (SWR) value of a signal in the transmission path of the antenna based at least in part on the measured signals provided with the directional coupler;
• a pi-shaped adjustable reactive matching circuit with a control unit, and farther comprising a longitudinal portion of the matching circuit that has a constant capacitance or inductance, and a plurality of transverse portions comprising at least one multiple-way switch, a common terminal of which is coupled to a separate conductor of said transmission path and wherein each change-over terminal is coupled to a ground conductor of the transmission path through a reactive element, the control unit having a first input adapted for operative coupling to a setting unit of an operating band of the radio device, and the control unit being operatively coupled to said directional coupler from its input side, and to said at least one switch in the matching circuit from its output side so as to permit setting of the switches, the control unit comprising:
• apparatus configured to define a trial array of the state combinations of the switches in the matching circuit based at least in part on a certain value of the transmitting power, an information associated with the operating band and the SWR value;
• apparatus configured to set the switches of the matching circuit in turn to the states according to each state combination of the trial array to determine the SWR values correspond to these combinations;
• apparatus configured to compare the determined SWR values and for finding the lowest one of them;
• and
• apparatus configured to start an adjusting process of the antenna matching at regular intervals.

A method for matching an antenna of a radio device, said method comprising:

• adjusting an impedance value of a reactive matching circuit coupled to said antenna, said act of adjusting being made based at least on:
• (1) an operating band signal indicative of the current operating band of a transmitter associated with the radio device;
• (2) a power level signal indicative of the current transmitting power of the transmitter;
• and/or (3) one or more impedance signals indicative of an impedance mismatch associated with a transmitted signal.

An apparatus for matching an antenna of a radio device, said apparatus comprising:

• a power amplifier comprising a power measuring signal output interface;
• a directional coupler comprising an impedance measuring signal output interface;
• a control unit coupled to said power measuring signal output interface and said impedance measuring signal interface;
• and
• a reactive matching circuit controlled at least in part by said control unit;
• wherein said power amplifier, directional coupler and reactive matching circuit are positioned along a transmission path of said radio device.