| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a VSWR monitoring circuit capable of accurate monitoring, even when the distance from a directional coupler for monitoring VSWR (voltage standing wave ratio) to a load circuit is different. <P>SOLUTION: The directional coupler 3 inserted in the middle between a transmission output circuit 1 and the load circuit 2 which are connected by a transmission line 10 takes out each part of a forward direction signal (progressive wave) and a reverse direction signal (reflected wave), and outputs them respectively to detectors 5, 6. A variable phase-shifter 4 is connected to the output side of the directional coupler 3, imparts phase rotation to the progressive wave and the reflected wave passing with each electric length changed by a control signal from an operation circuit 7. The operation circuit 7 calculates VSWR at the input end of the load circuit 2 based on the magnitude of each detection voltage signal outputted from the detectors 5, 6. <P>COPYRIGHT: (C)2005,JPO&NCIPI |
