Microwave heating apparatus and circuitry

Claim 1

A MICROWAVE RESONANT CAVITY UNIT FOR THE HEATING OF FOOD AND INDUSTRIAL PRODUCTS, SAID UNIT COMPRISING: A RESONANT CAVITY HAVING AN APERTURE IN ONE OF THE SIDES THEREOF; A MAGNETRON MOUNTED OUTSIDE OF THE CAVITY AND ADAPTED TO SUPPLY MICROWAVE ENERGY OF A GIVEN FREQUENCY THROUGH SAID APERTURE INTO SAID RESONANT CAVITY, SAID MAGNETRON COMPRISING A REENTRANT ANODE MEMBER INCLUDING A PLURALITY OF RESONANT CAVITIES ADAPTED TO HAVE STANDING WAVES INDUCED THEREIN, AND A CATHODE MEMBER COAXIAL WITH AND IMMEDIATELY ADJACENT SAID ANODE MEMBER, SAID GIVEN FREQUENCY BEING VARIABLE OVER A RANGE OF FREQUENCIES IN RESPONSE TO VARIATION OF THE MAGNETRON PLATE VOLTAGE; AND POWER SUPPLY MEANS COUPLED TO SAID MAGNETRON TO PROVIDE A VARYING MAGNETRON PLATE VOLTAGE TO SAID MAGNETRON WHEREBY SAID RESONANT CAVITY BECOMES RESONANT IN A PLURALITY OF DISCRETE RESONANT MODES IN RESPONSE TO THE VARYING FREQUENCY OF THE MICROWAVE ENERGY INTRODUCED THEREIN.