| 摘要 |
PROBLEM TO BE SOLVED: To control the impedance of a coupler and also attain the control of attenuation by connecting a diode between every coupling port of a sub- transmission line of the coupler and the ground and controlling the voltage applied to the diode to vary the resistance of the diode. SOLUTION: A positive voltage is applied to the control terminals Vc1 and Vc2 of diodes D1 and D2 which are connected to both ends of a sub-transmission line 13. When the positive voltage is increased from 0 V, the resistance of diodes D1 and D2 are reduced. Thus, the high frequency signal value that is sent from an input port Pi of a coupler 11 to an output port Po via a main transmission line 12 is reduced and the attenuation of a variable attenuator 10 is increased. Thereby the variable control is possible to the voltage applied to the terminals Vc1 and Vc2 and the resistance of diodes D1 and D2 are variable. Then the variable control is possible to the high frequency signal value that is sent to the port Po from the port Pi via the line 12. As a result, the variable control is possible to the attenuation of the attenuator 10.
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