Antenna impedance matching device and method for a portable radio telephone

A device for matching an antenna impedance in a portable radio telephone having transmission and receiving circuits, a foldable casing, the foldable casing movable between an unfolded position and a folded position, and an antenna movable between an extracted position and a retracted position, the device comprising:

• means for sensing the position of the foldable casing and the antenna, and for providing a sensing signal in response thereto;
• means for determining optimal antenna impedance values where each value corresponds with a different radio telephone configuration based on the position of the foldable casing and the antenna and whether the portable radio telephone is transmitting or receiving;
• means for storing a voltage corresponding to each of the optimal antenna impedance values;
• and
• means for matching the antenna impedance based on the sensing signal and a stored voltage corresponding to the sensed position of the foldable casing and the antenna.

A method of adjusting an antenna impedance in a portable radio telephone that includes transmission and receive circuits, a foldable casing enclosing the radio, the foldable casing movable between an unfolded position and a folded position, and an antenna movable between an extracted position from the foldable casing and a retracted position into the foldable casing, said method comprising the steps of:

• sensing a configuration of the radio telephone, wherein the configuration is defined by the position of the foldable casing, the position of the antenna and whether the radio telephone is in transmit or receive mode, and providing a sensing signal in response thereto;
• measuring a reception/transmission signal strength at a radio frequency for each of a plurality of antenna impedances and for each of a plurality of radio telephone configurations;
• determining an optimal antenna impedance for each configuration;
• storing a voltage corresponding to the optimal antenna impedance for each configuration;
• and
• setting the antenna impedance based on the stored voltage, according to the sensing signal provided in response to the sensed radio telephone configuration.

A method for matching an antenna impedance in a portable radio telephone that includes a radio having transmission and receiving circuits, a foldable case enclosing the radio, the foldable case movable between an unfolded position and a folded position, and an antenna movable between an extracted position from the foldable case and a retracted position into the foldable case, said method comprising the steps of:

• storing a plurality of values;
• sensing whether the antenna is in the extracted position in transmitting or receiving mode and producing at least one sensing signal in response thereto;
• selecting one of the plurality of values that corresponds with the sensing signal;
• and
• matching an the antenna impedance in response to the selected value, wherein the matched impedance corresponds with the impedance of the transmission or receiving circuit.

A device for matching antenna impedance in a radio telephone that includes a foldable case, said device comprising:

• memory for storing a plurality of digital values, each associated with a corresponding telephone configuration, wherein the configuration is defined by the position of the case, the position of the antenna and whether the telephone is transmitting or receiving;
• means for sensing the configuration;
• means for generating a sensing signal that reflects the sensed configuration;
• and
• means for matching the antenna impedance based on a selected one of the stored digital values that corresponds with the sensing signal.