Dielectric Constant Estimation Using TE/TM Reflection Ratio
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Solution Overview
Problem
Existing microwave heating devices face challenges in forming an optimal electromagnetic field distribution within the heating chamber due to unknown dielectric constants of objects, leading to inefficient heating without irregularities, and conventional non-contact dielectric constant measurement methods require known object shapes.
Innovation Solution
A dielectric constant estimation device that uses a transmitting and receiving antenna system to switch between TE and TM waves, calculate the TM/TE reflection ratio, and compare it with stored database values to estimate the object's dielectric constant, allowing for accurate estimation even without knowing the object's shape or size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional non-contact measurement methods (oscillation resonator method or free space method) are used to measure dielectric constant, then measurement can be performed without contact, but the object shape (such as thickness size) must be known in advance which limits applicability
Solution Approach 1:
The invention changes the measurement parameters from requiring shape information to using only size information. By measuring the reflected wave power at multiple frequencies and calculating the dielectric constant from the frequency characteristics, the system eliminates the need to know object shape in advance, making the measurement applicable to various unknown object geometries while maintaining non-contact operation
Solution Approach 2:
The invention transitions from single-frequency measurement to multi-frequency measurement, adding the frequency dimension to the measurement process. By measuring reflected wave power across multiple frequencies and analyzing the frequency characteristics, the system can determine dielectric constant without requiring prior knowledge of object shape, thus resolving the contradiction between non-contact measurement and adaptability to unknown shapes
2Productivity
If dielectric constant is unknown and temperature change during heating is not known, then electromagnetic field distribution cannot be optimized, but knowing dielectric constant in advance is required for efficient heating
Solution Approach 1:
The invention implements a feedback mechanism where the dielectric constant estimation device continuously measures the dielectric constant of the object during heating by analyzing reflected wave power at multiple frequencies. This real-time measurement feedback allows the heating system to adjust and optimize the electromagnetic field distribution dynamically, ensuring efficient heating even as the object's dielectric properties change with temperature
Solution Approach 2:
The invention performs preliminary measurement of the dielectric constant before heating begins by measuring reflected wave power at multiple frequencies. This preliminary information about the object's dielectric properties enables pre-optimization of the electromagnetic field distribution pattern, allowing efficient heating to start immediately without trial-and-error adjustments
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
Enables efficient and uniform heating of objects by accurately estimating their dielectric constants in a non-contact state, ensuring consistent heating patterns and preventing irregularities in the heating process.
Implementation Method 1
a receiving antenna configured to receive a reflected wave of the electromagnetic wave reflected from the object
Implementation Method 2
a transmitting antenna control part configured to switch a polarized wave of the electromagnetic wave emitted from the transmitting antenna to a TE wave or a TM wave
Implementation Method 3
a microwave oscillation part configured to generate a microwave for heating the object to be heated by dielectric heating
Data Source
AI summary
A dielectric constant estimation device which can estimate a dielectric constant of an object with high accuracy in a non-contact state even when a shape of the object is indefinite, and a microwave heating device equipped with the dielectric constant estimation device. The dielectric constant estimation device includes a transmitting antenna and a receiving antenna which can switch a polarized wave of an electromagnetic wave between a TE wave and a TM wave. Based on a reflected wave of the TE wave and a reflected wave of the TM wave from the object, the dielectric constant estimation device calculates a TM/TE reflection ratio, and compares the calculated TM/TE reflection ratio and dielectric constant data of theoretical values stored in a memory part in advance in the form of database with each other so that a dielectric constant of the object is estimated.