A system and method for defrosting a load are presented. Radio frequency (RF) signals are supplied to a transmission path that is electrically coupled to one or more electrodes that are positioned proximate to a cavity to cause the one or more electrodes to radiate RF electromagnetic energy. An RF power value of the RF signal along the transmission path is periodically measured resulting in RF power values and a rate of change of the RF power values is determined. A low-loss indicator value is determined using the RF power values, wherein the low-loss indicator value is at least partially determined by a dielectric loss of a load in the cavity. A controller determines, using the rate of change of the RF power values and the low-loss indicator value, that the load is in a defrosted state and stops supplying the RF signals.

A microwave heating method and a microwave heating device are provided. The microwave heating method includes the following steps. An electric field mode distribution at each frequency point generated by the microwave outputted from each input port of the heating chamber is calculated. A frequency, phase, and power of the microwave outputted from each input port are changed to generate a corresponding electric field mode distribution. The electric field mode distributions generated by the input ports are synthesized into a synthesized electric field mode distribution. A power density distribution is calculated. It is calculated whether spatial uniformity of the power density distribution is greater than a target value. The controller heats the object to be heated through the microwave corresponding to the frequency, phase, and power emitted by the microwave transmitter corresponding to each input port.

A microwave heating method and a microwave heating device are provided. The microwave heating method includes the following steps. An electric field mode distribution at each frequency point generated by the microwave outputted from each input port of the heating chamber is calculated. A frequency, phase, and power of the microwave outputted from each input port are changed to generate a corresponding electric field mode distribution. The electric field mode distributions generated by the input ports are synthesized into a synthesized electric field mode distribution. A power density distribution is calculated. It is calculated whether spatial uniformity of the power density distribution is greater than a target value. The controller heats the object to be heated through the microwave corresponding to the frequency, phase, and power emitted by the microwave transmitter corresponding to each input port.

A method for identifying a cooking level of a food load in an electromagnetic cooking device is disclosed. The method includes controlling a frequency and a phase of a first RF signal and a second RF signal and amplifying the first RF signal and the second RF signal thereby generating a first RF feed and a second RF feed. The method further includes emitting the first RF feed and the second RF feed into an enclosed cavity to heat a food load and measuring at least one reflection signal. The method further includes calculating a Q-factor for the enclosed cavity based on the reflection signal, monitoring the Q-factor, and identifying a change in the Q-factor exceeding a predetermined change threshold. In response to identifying the change exceeding the predetermined change threshold, a cooking level for the food load is identified.

A method for identifying a cooking level of a food load in an electromagnetic cooking device is disclosed. The method includes controlling a frequency and a phase of a first RF signal and a second RF signal and amplifying the first RF signal and the second RF signal thereby generating a first RF feed and a second RF feed. The method further includes emitting the first RF feed and the second RF feed into an enclosed cavity to heat a food load and measuring at least one reflection signal. The method further includes calculating a Q-factor for the enclosed cavity based on the reflection signal, monitoring the Q-factor, and identifying a change in the Q-factor exceeding a predetermined change threshold. In response to identifying the change exceeding the predetermined change threshold, a cooking level for the food load is identified.

In a method for detecting a standstill of a rotatable microwave distribution apparatus of a household microwave appliance, while microwaves are being supplied into a cooking compartment of the household microwave appliance, a microwave leakage radiation for angle-dependent recurring fluctuations is monitored and an action in the absence of such fluctuations being detected.

A method for analyzing a frequency response of a cooking device is disclosed. The method comprises controlling a plurality of RF signals within an operating range of the cooking device at plurality of phase shifts between a first RF signal and a second RF signal. A plurality of efficiencies of at least one reflection signal in the resonant cavity are measured in response to a plurality of RF feeds generated from the RF signals for the plurality of phase shifts. The frequency response of the resonant cavity is modeled with a numeric model and a plurality of interpolation parameters for the numeric model are calculated based on the plurality of measured efficiencies of the RF feeds. The frequency response of the cavity is estimated for the operating range of the cooking device based on the numeric model with the plurality of interpolation parameters.

A method for analyzing a frequency response of a cooking device is disclosed. The method comprises controlling a plurality of RF signals within an operating range of the cooking device at plurality of phase shifts between a first RF signal and a second RF signal. A plurality of efficiencies of at least one reflection signal in the resonant cavity are measured in response to a plurality of RF feeds generated from the RF signals for the plurality of phase shifts. The frequency response of the resonant cavity is modeled with a numeric model and a plurality of interpolation parameters for the numeric model are calculated based on the plurality of measured efficiencies of the RF feeds. The frequency response of the cavity is estimated for the operating range of the cooking device based on the numeric model with the plurality of interpolation parameters.

An antenna system comprises a transmission member and an antenna at a distal end of the transmission member. The antenna includes a first conductive arm, an insulator extending around the first conductive arm, and a second conductive arm wound around at least a first portion of the insulator to form a second conductive arm coil. A property of the insulator varies along an insulator longitudinal axis of the insulator. The insulator includes a set of formed patterns along at least a portion of the insulator longitudinal axis.

An antenna system comprises a transmission member and an antenna at a distal end of the transmission member. The antenna includes a first conductive arm, an insulator extending around the first conductive arm, and a second conductive arm wound around at least a first portion of the insulator to form a second conductive arm coil. A property of the insulator varies along an insulator longitudinal axis of the insulator. The insulator includes a set of formed patterns along at least a portion of the insulator longitudinal axis.