| 摘要 |
PROBLEM TO BE SOLVED: To provide a radio transmitter capable of reducing work for adjusting a matching circuit in a transmission antenna. SOLUTION: The on-vehicle radio transmitter 10 for transmitting a data signal from a signal source 13 from an antenna section 11 to the outside by radio comprises the matching circuit 14 for adjusting impedance by changing the capacity of a variable-capacitance diode 16; a feeder 21 for connecting the matching circuit 14 to the signal source 13; a directional coupler 17 for separating and detecting a backward signal, where a forward signal toward the antenna section 11 from the signal source 13 is reflected at the side of the antenna section 11 for returning to the feeder 21; a detector 19 for detecting the backward signal detected by the directional coupler 17; and a control circuit 20 for applying a control voltage to the variable-capacitance diode 16 so that a detection voltage outputted by the detector 19 is reduced. COPYRIGHT: (C)2007,JPO&INPIT
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