TRACKING CIRCUIT FOR MATCHED TUNER CIRCUIT OF TRANSMITTER AND TRACKING METHOD FOR MATCHED TUNER CIRCUIT

摘要

PROBLEM TO BE SOLVED: To provide a matched tuner circuit using the VSWR(voltage standing wave ratio) and also to provide a tracking method of the matched tuner circuit. ;SOLUTION: A matched tuner circuit 3 secures impedance matching between a transmission power amplifying part 1 and an antenna 5 by means of variable elements of a variable coil and/or a variable capacitor. Then a control (tracking) circuit of the circuit 3 consists of a CM wattmeter 11 which is placed at the output side of the part 1, a calculation comparison circuit 13 which calculates a VSWR from the traveling-wave voltage Vf and the reflected wave voltage Vr which are detected by the wattmeter 11 and also detects the change of the VSWR, and a variable element drive circuit 14 which drives the variable elements to increase or decrease the inductance or capacitance when the VSWR calculated by the circuit 13 is larger then the prescribed value. Then the circuit 14 is controlled by the output of the circuit 13, so that the VSWR is reduced less than the prescribed value.;COPYRIGHT: (C)1998,JPO