Patent ID: 6819052
Filing Date: 2004-11-16
Classification: H01J,H01P

Abstract:
An impedance detecting method comprising:inputting a progressive wave and a reflected wave output by a directional coupler connected to an object to be connected, as a first input signal and a second input signal, which are identical in frequency to each other and are different in phase from each other; generating a first generated signal and a second generated signal, which are identical in frequency to and different by a first reference phase difference from the first input signal, on a basis of the first input signal; a third generated signal and a fourth generated signal, which are identical in frequency to and different by a second reference phase difference from the second input signal, on a basis of the second input signal; mixing the first generated signal and the third generated signal to detect relative phase difference between the first generated signal and the third generated signal, as a first relative phase difference; mixing the second generated signal and the fourth generated signal to detect relative phase difference between the second generated signal and the fourth generated signal, as a second relative phase difference; referring to a relationship prepared in advance among the first relative phase difference, the second relative phase difference, and a true phase difference between the first input signal and the second input signal, to detect a true phase difference between the progressive wave and the reflected wave; mixing the first generated signal and the third generated signal to detect an amplitude ratio of the third generated signal to the first generated signal; mixing the second generated signal and the fourth generated signal to detect an amplitude ratio of the fourth generated signal to the second generated signal; and detecting an input impedance of the object to be connected on a basis of the detected true phase difference between the progressive wave and the reflected wave, and the detected amplitude ratios.