Simplified adaptive impedance matching circuit using measurement of standing wave amplitude

This paper presents a novel adaptive impedance matching circuit using measurement of standing wave amplitude. This circuit is realized with a simpler structure than the conventional techniques. The reflection phase range can be identified by comparing the standing wave amplitudes measured at some detectors on the feed line. The reflection phase measurement method is verified by the experiments. And, for the reflection amplitude, it is possible to identify the range by using the same circuit. Moreover, the control of this adaptive matching circuit does not need a digital computer. The presented circuit can improve the mismatch loss by more than 1.2dB when VSWR=4.