Dielectric Constant Estimation Using TE/TM Reflection Ratios
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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 and temperature changes of objects, leading to inefficient and irregular heating, especially when the object's size is unknown. Additionally, current non-contact dielectric constant measurement methods require known object shapes to accurately estimate the dielectric constant.
Innovation Solution
A dielectric constant estimation device and microwave heating device that switch between TE and TM wave polarizations and calculate the TM/TE reflection ratio using antennas at varying angles, allowing for accurate dielectric constant estimation and efficient heating without contact, even when the object's shape is indefinite. This device includes a transmitting antenna, receiving antenna, and a control system that compares calculated reflection ratios with stored data to adjust the heating pattern based on estimated dielectric constants.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If non-contact dielectric constant measurement methods are used, then measurement convenience is improved, but measurement precision deteriorates when object shape is unknown
Solution Approach 1:
The invention changes the parameter of wave polarization from a single state to multiple states (TE and TM waves). By measuring reflection coefficients in different polarization states and calculating their ratio, the system can determine dielectric constants without requiring prior knowledge of object shape or size, thus maintaining measurement convenience while improving precision.
Solution Approach 2:
The invention introduces an intermediary parameter - the TM/TE reflection ratio - which serves as a bridge between the measurable reflection coefficients and the target dielectric constant. This intermediary allows the system to eliminate the influence of unknown object geometry, enabling accurate non-contact measurement without requiring shape information.
2Device complexity
If microwave frequency is fixed, then device complexity is reduced, but heating efficiency deteriorates when dielectric constant changes with temperature
Solution Approach 1:
The invention makes the microwave frequency dynamic rather than fixed. The frequency is automatically adjusted based on real-time dielectric constant measurements obtained through the polarization ratio method. This dynamic adaptation ensures optimal heating efficiency throughout the heating process even as the object's dielectric properties change with temperature, without requiring complex manual intervention.
Solution Approach 2:
The system implements a feedback mechanism where the dielectric constant is continuously measured using TE and TM wave polarization ratios, and this information is used to adjust the microwave frequency in real-time. This closed-loop control maintains optimal heating efficiency throughout the heating process by adapting to temperature-induced changes in dielectric properties.
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 high-accuracy dielectric constant estimation and efficient heating treatment without irregularities, even for objects of unknown size, by adjusting the microwave frequency and polarization based on real-time dielectric constant measurements, ensuring consistent and effective heating.
Implementation Method 1
a transmitting antenna 4 for emitting an electromagnetic wave at a predetermined antenna angle with respect to an object to be heated; a receiving antenna 6 for receiving a reflected wave of the electromagnetic wave reflected from the object to be heated
Implementation Method 2
a microwave oscillation part 14 for generating a microwave to heat the object to be heated by dielectric heating
Data Source
Figure 1(a)~1(b)
Figure 2(a)~2(c)
Figure 3
AI summary
To provide 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 (4) and a receiving antenna (6) 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 (10) in advance in the form of database with each other so that a dielectric constant of the object is estimated.