| 摘要 |
PROBLEM TO BE SOLVED: To make an antenna small in size in the case of receiving both AM and FM waves. SOLUTION: A tuning circuit 12 tunes a signal received by an antenna 11 and inputs the signal to a receiver 13. In this case, the tuning circuit 12 uses a varactor diode 25 and a microcomputer in the receiver 13 gives a control voltage to the varactor diode 25 while adjusting the voltage. In this way, the reactance of the tuning circuit 12 can easily be adjusted and a single loop antenna whose diameter is, e.g. several tens of cm or below is employed for the antenna 11.
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