Microwave Heating Device Reflected Wave Detection Accuracy
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Solution Overview
Problem
Conventional microwave heating devices lack accurate detection of the state of an object being heated due to insufficient understanding of the relationship between reflected wave detection and in-tube standing waves in waveguides, making it difficult to determine the optimal placement of directional couplers for improved detection accuracy.
Innovation Solution
A microwave heating device with a reflected-wave detection unit positioned near the antinode of an in-tube standing wave, specifically disposed away from the standing-wave stabilizing part by an odd multiple of 1/4 of the in-tube wavelength, to enhance the detection accuracy of reflected waves.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the reflected-wave detection unit is placed in the waveguide without considering the standing wave pattern, then the device structure is simple, but the detection accuracy of the reflected wave is insufficient
Solution Approach 1:
The patent applies parameter changes by positioning the reflected-wave detection unit at specific locations within the waveguide based on standing wave characteristics. By changing the spatial parameter (position) to coincide with antinodes of the standing wave, the detection accuracy is significantly improved. The position is determined by the relationship: distance from the open end = (2n+1)×λ/4, where λ is the wavelength and n is an integer.
Solution Approach 2:
The patent replaces mechanical trial-and-error positioning methods with a theoretical electromagnetic field-based positioning system. Instead of mechanically adjusting the detector position to find optimal points, the invention uses electromagnetic theory to calculate and determine the exact positions of antinodes where maximum detection sensitivity occurs, substituting mechanical search with electromagnetic field analysis.
2Measurement precision
If the directional coupler is positioned away from the standing-wave stabilizing part by an odd multiple of 1/4 wavelength, then the detection sensitivity is improved, but the positioning precision requirement increases
Solution Approach 1:
The patent changes the positioning parameter from arbitrary placement to precise placement at antinodes of the standing wave. The position is calculated using the formula: distance from open end = (2n+1)×λ/4. This parameter change transforms the positioning from a general structural consideration to a precise electromagnetic field-based location, maximizing detection sensitivity while providing a clear theoretical basis for manufacturing.
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 configuration allows for more accurate detection of the object's heating state by increasing the sensitivity and frequency stability of reflected wave detection, enabling better monitoring of the heating process, such as the thawing of frozen food.
Implementation Method 1
an in-tube standing wave that occurs inside the waveguide
Implementation Method 2
a microwave returning from the heating chamber to the microwave generating unit
Data Source
Figure 1
Figure 2
Figure 3
AI summary
Microwave heating device (50) includes: heating chamber (2) to accommodate heating target object (1); magnetron (3) to generate a microwave; waveguide (10) to transmit the microwave generated by the microwave generating unit to heating chamber 2; and directional coupler (6) including a reflected-wave detection unit to detect a part of a reflected wave. Directional coupler (6) is disposed at the position of antinode (302) of standing wave (301) that occurs inside waveguide (10). The present configuration makes possible an increase in detection accuracy of the reflected wave, resulting in more accurate detection of the state of object (1) being heated.