Coherent RF Feed Control for Uniform Microwave Heating
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Solution Overview
Problem
Conventional microwave ovens often result in non-uniform heating due to the use of a single, non-coherent microwave source, leading to inefficiencies in cooking processes.
Innovation Solution
The implementation of a solid-state radio frequency (RF) cooking appliance with multiple RF feeds that produce dynamic electromagnetic wave patterns by controlling phase and amplitude, allowing for coherent irradiation within an enclosed cavity to achieve uniform heating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single non-coherent microwave source is used, then the device complexity is reduced, but the heating uniformity deteriorates
Solution Approach 1:
The single microwave source is divided into multiple coherent sources (first and second microwave sources) that can be independently controlled. Each source feeds into separate waveguides and can be individually adjusted for phase and amplitude, allowing precise control over the electromagnetic field distribution to achieve uniform heating across different food items.
Solution Approach 2:
The system dynamically adjusts the phase and amplitude of each microwave source based on the position and type of food item. The control unit modifies the operational parameters of each microwave source in real-time to optimize heating uniformity for different cooking scenarios.
2Manufacturing precision
If multiple RF feeds are implemented, then the heating uniformity is improved, but the device complexity increases
Solution Approach 1:
Multiple waveguides are designed with identical or similar structural configurations, allowing them to perform the same function of guiding microwave energy into the cooking cavity. This standardized approach simplifies the overall system design and manufacturing while achieving the goal of uniform heating through multiple feeds.
Solution Approach 2:
The system incorporates a control unit that monitors and adjusts the phase and amplitude of each microwave source based on the detected position and characteristics of the food item. This feedback mechanism optimizes the performance of the multi-feed system without requiring complex manual adjustments.
3Power
If coherent control with phase and amplitude adjustment is applied, then the power coupling efficiency is maximized, but the control complexity increases
Solution Approach 1:
The control unit automatically adjusts the phase and amplitude of each microwave source based on feedback from the food item detection system. This automated feedback control achieves optimal power coupling efficiency without requiring manual intervention or complex user operations.
Solution Approach 2:
The system changes the operational parameters (phase and amplitude) of each microwave source to optimize power transfer to the food item. By systematically adjusting these parameters based on food position and type, the system maximizes heating efficiency while keeping the control mechanism manageable.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables precise control of electromagnetic fields, maximizing the coupling of RF power with the object being heated, resulting in more efficient and uniform cooking by exploiting interference patterns for enhanced power distribution.
Implementation Method 1
A conventional microwave oven cooks food by a process of dielectric heating in which a high-frequency alternating electromagnetic field is distributed throughout an enclosed cavity. Microwave frequencies at or around 2.45 GHz cause dielectric heating primarily by absorption of energy in water.
Implementation Method 2
Microwave frequencies at or around 2.45 GHz cause dielectric heating primarily by absorption of energy in water.
Implementation Method 3
Multiple RF feeds at different locations in the enclosed cavity produce dynamic electromagnetic wave patterns as they radiate. The multiple RF feeds may radiate waves with separately controlled electromagnetic characteristics to maintain coherence (that is, a stationary interference pattern) within the enclosed cavity.
Data Source
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AI summary
A method (100) of coherently controlling irradiation of an object in an enclosed cavity by at least two radio frequency (RF) feeds (26A-D) includes setting an amplitude, a phase and a frequency for each of the RF feeds (110); actuating all of the RF feeds with the respectively set amplitudes, phases and frequencies to irradiate the object (112, 114, 116); measuring a reflected power at each of the RF feeds (118); characterizing a complete scattering matrix (124) of the enclosed cavity (116) while the object is being irradiated; and adjusting the power, the phase and the frequency for each of the RF feeds (26A-D) based on the complete scattering matrix (124) and values of the power, the phase and the frequency of the RF feeds (26A-D) before adjusting.