Abstract: A substance treatment apparatus includes an RF signal source, power detection circuitry, a controller, and a transmission path between the RF signal source and a first electrode that radiates electromagnetic energy into a chamber. The RF signal source includes a solid-state amplifier that generates an RF signal. The power detection circuitry detects reflected signal power along the transmission path. Based on the reflected signal power, the controller modifies values of variable components within an impedance matching network electrically coupled along the transmission path to adjust a magnitude of the reflected signal power. The impedance matching network may have a double-ended input connected to a balun, and a double-ended output connected to the first electrode and to a second electrode. Alternatively, the impedance matching network may have a single-ended input connected to the RF signal source, and a single-ended output connected to the first electrode. The second electrode may be grounded.

Abstract: A system and method for tuning an impedance network of a device is provided. An RF signal is provided through a transmission path connected to an impedance matching network that includes a first variable component and a second variable component. A phase angle between a forward signal and a reflected signal along the transmission path is determined. Based on the phase angle between the forward signal and the reflected signal, the first variable component is modified to improve an impedance match between the RF signal source and the electrode. After modifying the first variable component, a ratio of a power of the reflected signal to a power of the forward signal is determined, and an inductance of the second variable component is modified to reduce the ratio of a power of the reflected signal to a power of the forward signal.

Abstract: A system and method for defrosting or heating are presented. A radio frequency (RF) signal source provides, through a transmission path, an RF signal to an electrode that is proximate to a cavity of a defrosting system. A rate of change of a ratio of a reflected RF power measurement and a forward RF power measurement along the transmission path is determined to have transitioned from a relatively high value to a relatively low value. At a point in time when the determination is made, the RF signal is provided to the electrode for an additional time duration beyond the point in time, and provision of the RF signal to the electrode is ceased when the additional time duration has expired.

Abstract: A device includes an antenna configured to be disposed within a cavity of an appliance. The appliance includes an electrode and the antenna includes a sheet of conductive material having a surface area that is equal to or greater than a surface area of the electrode. The device includes a voltage sensor coupled to the antenna, an output device, and a controller coupled to the voltage sensor and the output device. The controller is configured to generate an output at the output device. The output is determined by a voltage of the antenna.

Abstract: An embodiment of a heating system includes a cavity configured to contain a load, a thermal heating system, and an RF heating system. The RF heating system includes a system controller, an RF signal source, one or more electrodes that receive an RF signal from the RF signal source and radiate resultant electromagnetic energy into the cavity, and a variable impedance matching network coupled between the RF signal source and the one or more electrodes. The system controller may monitor an impedance state of the variable impedance matching network to identify the occurrence of a change point. The system controller may estimate the mass of the load and a time and/or energy requirement for cooking the load based on the change point. The system controller may take action by turning off the RF heating system and/or thermal heating system when the time or energy requirement has been met.

Abstract: A thermal increase system includes one or more multi-level electrodes configured to radiate electromagnetic energy into a cavity in response to receiving a radio frequency (RF) signal from an RF signal source. Each multi-level electrode is positioned adjacent to a wall of the cavity, and each multi-level electrode includes a base portion coupled to an elevated portion. A radiating surface of the elevated portion is at a height of at least 0.5 centimeters (cm) from a radiating surface of the base portion.

Abstract: A system and method for tuning an impedance network of a device is provided. An RF signal is provided through a transmission path connected to an impedance matching network that includes a first variable component and a second variable component. A phase angle between a forward signal and a reflected signal along the transmission path is determined. Based on the phase angle between the forward signal and the reflected signal, the first variable component is modified to improve an impedance match between the RF signal source and the electrode. After modifying the first variable component, a ratio of a power of the reflected signal to a power of the forward signal is determined, and an inductance of the second variable component is modified to reduce the ratio of a power of the reflected signal to a power of the forward signal.

Abstract: An embodiment of a microwave power generation module includes an amplifier arrangement, an impedance matching element, and a resonant element. The amplifier arrangement includes a transistor with a transistor input and a transistor output. The impedance matching element is formed from a planar conductive structure. The planar conductive structure has a proximal end and a distal end, and the proximal end is electrically coupled to the transistor output. The resonant element has a proximal end electrically coupled to the distal end of the planar conductive structure, and the resonant element is configured to radiate electromagnetic energy having a microwave frequency in a range of 800 megahertz (MHz) to 300 gigahertz (GHz). A combination of the impedance matching element and the resonant element is configured to perform an impedance transformation between an impedance of the transistor and an impedance of an air cavity.

Abstract: A radio frequency (RF) heating and defrosting apparatus may include an electrode which, when supplied with RF signal energy, may responsively radiate electromagnetic energy into a cavity of the RF heating and defrosting apparatus. This radiated electromagnetic energy may cause a thermal increase of a load in the cavity. A capacitor may be formed from a portion of the electrode and a conductive plate disposed adjacent to the electrode. The conductive plate may be coupled to a ground reference structure. Dielectric material(s) having a low dielectric constant may be disposed directly between the electrode and the conductive plate.

Abstract: A system and method for tuning an impedance network of a device is provided. An RF signal is provided through a transmission path connected to an impedance matching network that includes a first variable component and a second variable component. A phase angle between a forward signal and a reflected signal along the transmission path is determined. Based on the phase angle between the forward signal and the reflected signal, the first variable component is modified to improve an impedance match between the RF signal source and the electrode. After modifying the first variable component, a ratio of a power of the reflected signal to a power of the forward signal is determined, and an inductance of the second variable component is modified to reduce the ratio of a power of the reflected signal to a power of the forward signal.

Abstract: Example systems have a defrost system that can receive a first RF signal at a first frequency to defrost a load. An air treatment device can receive a second RF signal at a second frequency and perform an air treatment process. An RF signal source has a power output, and a switching arrangement selectively electrically connects the defrost system and the first air treatment device to the power output of the RF signal source. A controller can electrically connect one of the defrost system and the first air treatment device to the power output of the RF signal source. When the defrost system is electrically connected, the RF signal source outputs the first RF signal at the first frequency, and when the first air treatment device is electrically connected, the RF signal source outputs the second RF signal at the second frequency.

Abstract: A defrosting system includes an RF signal source, an electrode proximate to a cavity within which a load to be defrosted is positioned, and a transmission path between the RF signal source and the electrode. The system also includes power detection circuitry coupled to the transmission path and configured repeatedly to take forward and reflected RF power measurements along the transmission path. A system controller repeatedly determines, based on the forward and reflected RF power measurements, a calculated rate of change, and repeatedly compares the calculated rate of change to a threshold rate of change. When the calculated rate of change compares favorably with the threshold rate of change, the RF signal source continues to provide the RF signal to the electrode until a determination is made that the defrosting operation is completed, at which time the RF signal source ceases to provide the RF signal to the electrode.

Abstract: An RF system includes an RF signal source and a single-ended or double-ended impedance matching network. Non-linear devices, such as gas discharge tubes, are coupled in parallel with components of the impedance matching network. The non-linear devices are insulating below a breakdown voltage and conductive above the breakdown voltage. The system also includes measurement circuitry configured to measure one or more parameters that reflect changes in the impedance of the impedance matching network. A system controller modifies operation of the system when a rate of change of any of the monitored parameter(s) exceeds a predetermined threshold.

Abstract: A system is configured to perform an operation that results in increasing a thermal energy of a load. The system includes a radio frequency signal source configured to supply a radio frequency signal, an electrode coupled to the radio frequency signal source, and a variable impedance network that includes at least one variable passive component. The variable impedance network is coupled between the radio frequency signal source and the electrode. The system includes a controller configured to determine an operation duration based upon a configuration of the variable impedance network, and to cause the radio frequency signal source to supply the radio frequency signal for the operation duration.

Abstract: An embodiment of a heating system includes a cavity configured to contain a load, a thermal heating system (e.g., a convection, radiant, and/or gas heating system) in fluid communication with the cavity and configured to heat air, and an RF heating system. The RF heating system includes an RF signal source configured to generate an RF signal, first and second electrodes positioned across the cavity and capacitively coupled, a transmission path electrically coupled between the RF signal source and one or more of the first and second electrodes, and a variable impedance matching network electrically coupled along the transmission path between the RF signal source and the one or more electrodes. At least one of the first and second electrodes receives the RF signal and converts the RF signal into electromagnetic energy that is radiated into the cavity.

Abstract: A defrosting system includes a radio frequency (RF) signal source, at least one electrode proximate to a cavity within which a load to be defrosted is positioned, a transmission path between the RF signal source and the electrode, at least one bus bar in the transmission path that includes multiple ports to which the electrode may be coupled, a repositionable shelf that is attached to the electrode, and multiple support structures disposed at side-walls of the cavity that support the repositionable shelf. Standoff isolators may attach the electrode to the repositionable shelf and may electrically isolate the electrode from the repositionable shelf. The vertical position of the electrode may be changed by moving the repositionable shelf to be supported by different support structures of the multiple support structures while coupling the electrode to a different port of the multiple ports of the bus bar.

Abstract: A system includes a cavity configured to receive a container. The container is configured to contain a plurality of grains. The system includes a radio frequency (RF) signal source configured to supply an RF signal, an impedance matching network electrically coupled to an output of the RF signal source, a transmission path coupled to the impedance matching network, and a first electrode in the cavity. The first electrode is coupled to the transmission path and configured to radiate electromagnetic energy into the cavity as a result of receiving the RF signal. The system includes power detection circuitry configured to measure a magnitude of a reflected signal along the transmission path and a controller configured to modify an impedance transformation performed by the impedance matching network based on the magnitude of the reflected signal.

Abstract: Example systems have a defrost system that can receive a first RF signal at a first frequency to defrost a load. An air treatment device can receive a second RF signal at a second frequency and perform an air treatment process. An RF signal source has a power output, and a switching arrangement selectively electrically connects the defrost system and the first air treatment device to the power output of the RF signal source. A controller can electrically connect one of the defrost system and the first air treatment device to the power output of the RF signal source. When the defrost system is electrically connected, the RF signal source outputs the first RF signal at the first frequency, and when the first air treatment device is electrically connected, the RF signal source outputs the second RF signal at the second frequency.

Abstract: A defrosting system includes an RF signal source, an electrode proximate to a cavity within which a load to be defrosted is positioned, and a transmission path between the RF signal source and the electrode. The system also includes power detection circuitry coupled to the transmission path and configured repeatedly to take forward and reflected RF power measurements along the transmission path. A system controller repeatedly determines, based on the forward and reflected RF power measurements, a calculated rate of change, and repeatedly compares the calculated rate of change to a threshold rate of change. When the calculated rate of change compares favorably with the threshold rate of change, the RF signal source continues to provide the RF signal to the electrode until a determination is made that the defrosting operation is completed, at which time the RF signal source ceases to provide the RF signal to the electrode.

Abstract: A thermal increase system includes a cavity, a first electrode disposed in the cavity, a second electrode disposed in the cavity, and a self-oscillator circuit that produces a radio frequency signal that is converted into electromagnetic energy that is radiated into the cavity by the first and second electrodes. The self-oscillating circuit includes the first electrode and the second electrode. In an embodiment, the first electrode is a first plate in a capacitor structure and the second electrode is a second plate in the capacitor structure. The cavity and a load contained within the cavity operates as a capacitor dielectric of the capacitor structure. A resonant frequency of the self-oscillator circuit is at least partially determined by a capacitance value of the capacitor structure.