Microwave power source apparatus for microwave oscillator comprising means for automatically adjusting progressive wave power and control method therefor

A microwave power source apparatus comprising:

• a microwave oscillator for generating a microwave;
• a microwave transmission line connected between said microwave oscillator and a microwave load, said microwave transmission line being a waveguide;
• power source means for supplying an electric power for generating said microwave to said microwave oscillator;
• measuring means, mounted on said microwave transmission line, for detecting a voltage standing wave of said microwave being generated by said microwave oscillator and propagating on said microwave transmission line and for measuring either one of an impedance seen looking toward said microwave load at a mounted point thereof and a reflection coefficient thereat based on said detected voltage standing wave, said measuring means comprising at least three probes mounted at different points at predetermined spaces in the longitudinal direction of said waveguide so that each of said spaces therebetween is not set at a product of any natural number and half a guide wavelength of said microwave propagating in said waveguide;
• first calculating means for calculating an incident wave power and a reflected wave power of said microwave propagating on said microwave transmission line from said microwave oscillator toward said microwave load based on either one of said impedance and said reflection coefficient measured by said measuring means;
• first control means for controlling said power source means to adjust said incident wave power of said microwave to a predetermined desirable adjustment value based on said incident wave power calculated by said first calculating means;
• comparator means for judging whether or not said reflected wave power calculated by said first calculating means is larger than a predetermined threshold power value;
• and
• output switch means for preventing said power source means from supplying the electric power to said microwave oscillator when it is judged by said comparator means that said reflected wave power calculated by said first calculating means is larger than said predetermined threshold power value.