| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a circulator which is excellent in an isolation characteristic. Ž<P>SOLUTION: An antenna 19 and a dummy load 15 connected to a port 2 each have an impedance of 50 Ω. A signal input to a port 1 being an input terminal of a distribution circuit 10 is distributed in equal amplitudes in opposite phases: one is input to a combiner 18 through a first base ground amplifier 11, a first matching circuit 16 and a third base ground amplifier 13, and the other is input to the combiner through a second base ground amplifier 12, a second matching circuit 17 and a fourth base ground amplifier 14. In such a case, a fluctuation in an impedance of the antenna 19 is compensated by controlling a current amount of a current source of the second base ground amplifier 12 and the capacitance of a parallel variable capacitor 119 of the second matching circuit 17. An output of the third base ground amplifier 13 and an output of the fourth base ground amplifier 14 are therefore negated in the combiner 18, and the outputs are not output from a port 3. Ž<P>COPYRIGHT: (C)2010,JPO&INPIT Ž
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