An electromagnetic cooking device is provided having a controller and a plurality of RF feeds configured to introduce electromagnetic radiation into an enclosed cavity to heat up a food load. The controller is configured to: (a) cause the generation of RF excitations at a specified frequency and phase shifts from each of the plurality of RF feeds for a predetermined time period; (b) during the predetermined time period: measure and analyze the backward power at the plurality of RF feeds to calculate efficiency, determine a coefficient of variation in the efficiency, and monitor the coefficient of variation to identify possible changes in a characteristic of the food load; and (c) repeatedly perform steps (a) and (b) until such time that a possible change is identified in a characteristic of the food load based on changes in the coefficient of variation. The characteristic may be the volume of the food load.

A food preparation appliance includes a housing, a conveyor, a thermal element, a first sensor, a second sensor, and a third sensor. The housing defines an inlet, an outlet, and a processing zone between the inlet and the outlet. The conveyor is configured to move a food product from the inlet, through the processing zone, and to the outlet. The thermal element is positioned within the processing zone. The first sensor is positioned proximate the inlet of the housing and along a lateral side of the conveyor or along a first cantilever arm extending laterally across the conveyor. The second sensor is positioned within the processing zone. The third sensor is positioned proximate the outlet of the housing and along a lateral side of the conveyor or along a second cantilever arm extending laterally across the conveyor.

Power amplifier electronics for controlling application of radio frequency (RF) energy generated using solid state electronic components may further be configured to control application of RF energy in cycles between high and low powers. The power amplifier electronics may include a semiconductor die on which one or more RF power transistors are fabricated, an output matching network configured to provide impedance matching between the semiconductor die and external components operably coupled to an output tab, and bonding wires bonded at terminal ends thereof to operably couple the one or more RF power transistors of the semiconductor die to the output matching network. The bonding wires may be copper bonding wires having a diameter of between about 10 microns and about 100 microns.

An electromagnetic cooking device and method of controlling the same is provided herein. The cooking device has a cavity in which a liquid is placed and a plurality of RF feeds configured to introduce electromagnetic radiation into the cavity for heating the liquid. A controller is provided and is configured to: analyze forward and backward power at the plurality of RF feeds to calculate efficiency; determine and monitor a coefficient of variation of the efficiency; detect a boiling state in the liquid based on changes in the coefficient of variation; and adjust a power level of the electromagnetic radiation in response to detection of the boiling state to prevent the liquid from splattering.

Systems and methods include a cooking appliance comprising a heating element disposed within a cooking chamber and operable to selectively emit waves at any of a plurality of powers and/or peak wavelengths, a camera operable to capture an image of the cooking chamber, and a computing device operable to supply power to the heating element to vary the power and/or peak wavelength of the emitted waves and generate heat within the cooking chamber, and instruct the camera to capture the image when the heating element is emitting at a stabilized power and/or peak wavelength. The computing device is operable to generate an adjusted captured image by adjusting the captured image with respect to the stabilized power and/or peak wavelength. The computing device comprises feedback components operable to receive the adjusted captured image, extract features, and analyze the one or more features to determine an event, property, measurement and/or status.

An air circulation system for an oven includes a plenum disposed proximate to the cooking chamber, an airflow generator configured to draw air from the cooking chamber through a chamber outlet port and discharge the air into the plenum, and an air heater configured to heat at least some of the air in the plenum prior to a portion of the air entering the cooking chamber from the plenum via air delivery orifices. The chamber outlet port includes outlet perforations combining to form a first geometric shape centered on an axis of the airflow generator. The air delivery orifices include a first set of inlet perforations and a second set of inlet perforations. The first and second sets of inlet perforations combine to form respective second and third geometric shapes that are disposed on opposite sides of the outlet perforations. The second and third geometric shapes are different than the first geometric shape.

A microwave heating device includes a heating chamber that accommodates an object to be heated, a microwave generator configured to generate microwaves, a wave guide tube configured to guide the microwaves to the heating chamber, and an electromagnetic field distribution adjustment device that is provided in a two-dimensional region located in at least a part of a wall face within the heating chamber. The electromagnetic field distribution adjustment device has a plurality of metal pieces arranged to fill a predetermined two-dimensional region, and a switch provided between two metal pieces adjacent to each other among the plurality of metal pieces. The switch is connected to the two metal pieces adjacent to each other through two conductors each of which is provided on a corresponding one of the two metal pieces adjacent to each other, and smaller than the two metal pieces adjacent to each other. According to the present aspect, uneven heating, which is caused by heating an object to be heated with a microwave heating device, can be reduced.

A transition device for a hollow waveguide comprises a rectangular structure comprising an inlet wall and interior extending from the inlet wall along a longitudinal axis. The inlet wall is configured to receive a transmission line comprising an antenna. The antenna forms a proximal end proximate to the inlet wall and a distal end configured to extend into the rectangular structure of the hollow waveguide. A channel is formed in the rectangular structure. The channel comprises a base forming a tuning surface. The tuning surface is configured to extend along a length of the antenna in a spaced configuration parallel to the longitudinal axis.

In certain examples, a food processing machine for processing a food product includes a housing defining a cavity, a conveyor with a belt comprising metal for conveying the food product through the cavity in a longitudinal direction, and a convection heating system for heating air in the cavity such that heated air heats the food product as the food product is conveyed through the cavity. A microwave launch box system is configured to emit microwave energy into the cavity in a lateral direction transverse to the longitudinal direction to thereby further heat the food product as the food product is conveyed through the cavity.

A thermal increase system may include re-radiators disposed in a cavity for containing a load. Microwave energy may be generated by one or more microwave generation modules, and directed toward the cavity during operation of the thermal increase system, thereby creating an electromagnetic field in the cavity. A system controller may control switches coupled between the re-radiators and corresponding ground nodes to selectively activate and de-activate the re-radiators. The system controller may control a switch coupled between a pair of re-radiators to re-distribute the electromagnetic field in the cavity. A phase shifter may be disposed between a pair of re-radiators, which may provide a phase shift to energy passed between the re-radiators. The phase shifter may be a variable shifter that applies a variable phase shift to the energy according to commands received from the system controller.