A TDR-based multilayered dielectric material thickness measurement system and method

Abstract

This invention discloses a TDR-based system and method for measuring the thickness of multilayer dielectric materials, relating to the field of microwave testing technology, enabling thickness measurement of multilayer dielectric materials in a non-destructive environment. The system includes: a vector network analyzer, an antenna module, and a metal calibration plate. The vector network analyzer emits microwave pulses at a set frequency to the multilayer dielectric material under test. The antenna module focuses the reflected waves generated by the microwave pulses as they pass through the multilayer dielectric material. The metal calibration plate is placed on the starting layer of the multilayer dielectric material to generate the first corresponding time-domain signal reflection peak when the microwave pulse is incident, thus locating the starting position of the multilayer dielectric material. The vector network analyzer also acquires the frequency-domain signal focused by the antenna module, performs a Fast Fourier Transform on the frequency-domain signal to obtain a time-domain signal, calculates the time-domain signal based on the starting position, and outputs the thickness parameters of each layer in the multilayer dielectric material under test.

Description

Technical Field

[0001] This invention relates to the field of microwave testing technology, and in particular to a system and method for measuring the thickness of multilayer dielectric materials based on TDR. Background Technology

[0002] In existing industrial production systems, to avoid safety accidents or irreversible losses, there are situations where it is necessary to measure the wall thickness of the medium in loading and transmission systems in non-shutdown scenarios and without damaging the equipment being tested. Examples include measuring the wall thickness of high-temperature furnaces, the thickness of containers containing corrosive materials, and the thickness of pipes in liquid transmission systems. Currently, existing methods for measuring the thickness of medium materials include ultrasonic thin-film thickness measurement, optical thickness measurement, and eddy current thickness detection technology.

[0003] Ultrasonic film thickness measurement mainly utilizes the propagation speed and reflection characteristics of ultrasonic waves in a dielectric material to detect the material thickness. An ultrasonic pulse is emitted into the material, and the thickness is calculated by measuring the propagation time and speed of the pulse. However, the accuracy of this method may be affected by material properties (such as material density and changes in the speed of sound within the material) and environmental factors (such as temperature).

[0004] Optical thickness measurement refers to measuring the thickness of a medium material by using the principles of light interference, diffraction, and laser ranging. Although optical methods have high precision in some applications, they require a high degree of surface smoothness and may be limited in transparent or semi-transparent materials.

[0005] Eddy current technology is based on the principle of electromagnetic induction. It measures the thickness of a conductive material by measuring the distribution of eddy currents in the material. This method is particularly suitable for measuring conductive materials such as metals, but it is not applicable to non-conductive media.

[0006] The aforementioned ultrasonic thin film thickness measurement, optical thickness measurement, and eddy current thickness detection technologies still have different limitations, making it difficult to detect the wall thickness of corrosive and erosive multilayer media materials in non-shutdown and non-damaged scenarios. Summary of the Invention

[0007] In view of this, this application provides a multilayer dielectric material thickness measurement system based on TDR, which realizes non-destructive thickness measurement of multilayer dielectric materials. The TDR is achieved by combining VNA with FFT. In the process, VNA narrowband receiving technology is used to obtain a high signal-to-noise ratio at each frequency point, thereby significantly improving the dynamic range and enabling the signal to penetrate high-loss media. This enables non-destructive thickness measurement of multilayer and thick-walled materials, and is suitable for thickness measurement of high-loss and multilayer dielectric materials.

[0008] The first aspect of this application provides a multilayer dielectric material thickness measurement system based on TDR, the system comprising: a vector network analyzer, an antenna module, and a metal calibration plate; wherein,

[0009] The vector network analyzer is used to emit microwave pulses to the multilayer dielectric material under test at a set frequency.

[0010] The antenna module is used to focus the reflected wave generated by the microwave pulse through the multilayer dielectric material under test;

[0011] The metal calibration plate is disposed on the starting layer of the multilayer dielectric material to be tested, and is used to generate the first corresponding time-domain signal reflection peak when the microwave pulse is incident, so as to locate the starting position of the multilayer dielectric material.

[0012] The vector network analyzer is also used to acquire frequency domain signals focused by the antenna module, perform fast Fourier transform on the frequency domain signals to obtain time domain signals, calculate the time domain signals according to the starting position, and output the thickness parameters of each layer of the multilayer dielectric material under test.

[0013] Optionally, the system further includes: a low-noise amplifier and a circulator;

[0014] The circulator is used to separate the microwave pulse and the reflected wave generated by the multilayer dielectric material under test, so as to optimize the microwave pulse and the reflected wave and ensure low-loss propagation of the microwave pulse and the reflected wave;

[0015] The low-noise amplifier is used to amplify the reflected wave with low noise.

[0016] Optionally, the system further includes a combiner; the combiner is connected to a low-noise amplifier, and the low-noise amplifier is connected to a circulator, forming a signal processing and enhancement link;

[0017] The combiner is used to combine multiple microwave pulses emitted by the vector network analyzer to obtain an enhanced incident signal.

[0018] Optionally, the antenna module includes an antenna and a focusing lens;

[0019] The antenna is used to receive and transmit microwave pulses;

[0020] The focusing lens is disposed on the microwave pulse propagation path of the antenna and is used to focus the microwave pulse emitted by the antenna to enhance the signal strength incident on the multilayer dielectric material under test.

[0021] Optionally, the circulator port of the circulator is provided with a through calibration element for through calibration of the circulator.

[0022] Optionally, the circulator port of the circulator is provided with a single-port calibration element for single-port calibration of the circulator.

[0023] The second aspect of this application provides a method for measuring the thickness of multilayer dielectric materials based on TDR, applied to the vector network analyzer of the TDR-based multilayer dielectric material thickness measurement system provided in the first aspect, the method comprising:

[0024] The frequency domain signal focused by the antenna module is acquired, and a fast Fourier transform is performed on the frequency domain signal to obtain the time domain signal;

[0025] The time of the reflection peak in each time domain is extracted and calculated to obtain the thickness parameters of each layer of the multilayer dielectric material to be tested.

[0026] Optionally, the time of the reflection peak in each time domain is extracted and calculated to obtain the thickness parameters of each layer in the multilayer dielectric material under test, including:

[0027] Mark the start time of the first reflection peak in the time-domain signal;

[0028] The starting position of the first layer of the multilayer dielectric material to be tested is determined by the starting time. The ending position of the previous layer is used as the starting position of the current layer. The difference between the starting and ending positions of the current layer is calculated, and the thickness parameters of each layer are output.

[0029] Optionally, the method further includes:

[0030] Samples of each layer of dielectric material were obtained, and the relative permittivity of each layer of the multilayer dielectric material to be tested was detected.

[0031] The time of the reflection peak in each time domain is extracted and calculated to obtain the thickness parameters of each layer in the multilayer dielectric material under test, including:

[0032] The relative permittivity is substituted into the set calculation module, and the time of the reflection peak in each time domain is extracted for calculation to obtain the thickness parameters of each layer of the multilayer dielectric material to be tested; wherein, the calculation module performs the calculation according to formula (1);

[0033] (1);

[0034] = , Represents the relative permittivity of the i-th dielectric layer. , This represents the time of the i-th reflection peak displayed in the time domain signal. It represents the speed of light.

[0035] Optionally, the method further includes:

[0036] Acquire samples of each layer of dielectric material and set the frequency range of the vector network analyzer according to the dielectric material.

[0037] The circulator is calibrated both via and single-port within the specified frequency range.

[0038] A third aspect of this application provides a vector network analyzer, comprising: a processor and a memory, the processor and the memory being connected via a communication bus; wherein the processor is used to call and execute a program stored in the memory; the memory is used to store the program, the program being used to implement the TDR-based multilayer dielectric material thickness measurement method provided in the second aspect of this application.

[0039] The fourth aspect of this application provides a computer-readable storage medium storing computer-executable instructions for performing a TDR-based method for measuring the thickness of multilayer dielectric materials as provided in the second aspect of this application.

[0040] Compared to existing technologies, this invention proposes a TDR-based system for measuring the thickness of multilayer dielectric materials. Microwave pulses are emitted into the dielectric material, and the reflected signals are scanned by a Vector Network Analyzer (VNA) to obtain a frequency domain signal. This signal is then converted to a time domain signal using a Fast Fourier Transform (FFT), and the thickness parameters of each layer in the multilayer dielectric material are calculated based on the converted time domain signal. This method of TDR using VNA combined with FFT employs narrowband VNA reception technology, achieving a high signal-to-noise ratio at each frequency point, thereby significantly improving the dynamic range. This allows the signal to penetrate high-loss media, enabling non-destructive thickness measurement of multilayer, thick-walled materials, suitable for high-loss, multilayer dielectric materials. Furthermore, the VNA itself can perform comprehensive error calibration, accurately eliminating system errors such as those from cables and fixtures, improving the accuracy of wall thickness detection. Attached Figure Description

[0041] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of this application. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0042] Figure 1This is a schematic diagram of the composition of the multilayer dielectric material thickness measurement system based on TDR proposed in the embodiments of this application;

[0043] Figure 2 This application provides an example of a block diagram of a measurement system for transmitting parameters in a vector network analyzer;

[0044] Figure 3 This is a schematic diagram of a time-domain signal obtained by processing a reflected wave, as an example, according to this application.

[0045] Figure 4 This is a schematic diagram of an example multilayer dielectric material to be tested according to this application;

[0046] Figure 5 This application provides an example of a block diagram of a measurement system for reflection parameters of a vector network analyzer;

[0047] Figure 6 This is a flowchart of the steps of the multilayer dielectric material thickness measurement method based on TDR proposed in the embodiments of this application. Detailed Implementation

[0048] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0049] In this application, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes the element.

[0050] Time Domain Reflectometry (TDR) is a time-domain measurement method that transmits a time-domain signal, such as a fast step pulse, to the device under test (DUT) and analyzes the time-domain signal generated by the pulse at impedance discontinuities. For example, it can be used to locate faults or measure distances by analyzing the time delay of the reflected echo.

[0051] Given the limitations of existing dielectric material thickness measurement technologies, this invention proposes a multilayer dielectric material thickness measurement system based on Time-Diffusive Reduction (TDR). Microwave pulses are emitted into the dielectric material, and the reflected signals are scanned by a Vector Network Analyzer (VNA) to obtain the frequency domain signal. Then, a Fast Fourier Transform (FFT) is used to convert the frequency domain signal into a time domain signal. Based on the converted time domain signal, the thickness parameters of each layer in the multilayer dielectric material are calculated. This method of TDR using VNA combined with FFT employs narrowband VNA receiving technology, achieving a high signal-to-noise ratio at each frequency point, thereby significantly improving the dynamic range. This allows the signal to penetrate high-loss media, enabling non-destructive thickness measurement of multilayer, thick-walled materials, suitable for high-loss, multilayer dielectric materials. Furthermore, the VNA itself can perform comprehensive error calibration, accurately eliminating system errors such as those from cables and clamps, improving the accuracy of wall thickness detection.

[0052] Figure 1 This is a schematic diagram of the composition of the multilayer dielectric material thickness measurement system based on TDR proposed in the embodiments of this application, as shown below. Figure 1 As shown, the TDR-based multilayer dielectric material thickness measurement system includes a vector network analyzer, an antenna module, a metal calibration plate, a low-noise amplifier, and a circulator.

[0053] The vector network analyzer is used to emit microwave pulses to the multilayer dielectric material under test at a set frequency.

[0054] The antenna module is used to focus the reflected wave generated by the microwave pulse through the multilayer dielectric material under test;

[0055] The metal calibration plate is disposed on the starting layer of the multilayer dielectric material to be tested, and is used to generate the first corresponding time-domain signal reflection peak when the microwave pulse is incident, so as to locate the starting position of the multilayer dielectric material; the starting position of the multilayer dielectric material is captured by the signal reflected by the calibration plate.

[0056] The vector network analyzer is also used to acquire frequency domain signals focused by the antenna module, perform fast Fourier transform on the frequency domain signals to obtain time domain signals, calculate the time domain signals according to the starting position, and output the thickness parameters of each layer of the multilayer dielectric material under test.

[0057] The circulator is used to separate the microwave pulse and the reflected wave generated by the multilayer dielectric material under test, so as to optimize the microwave pulse and the reflected wave and ensure low-loss propagation of the microwave pulse and the reflected wave;

[0058] The low-noise amplifier is used to amplify the reflected wave with low noise.

[0059] The multilayer dielectric material thickness measurement system based on TDR technology proposed in this application can perform measurements using transmission parameters and reflection parameters based on a vector network analyzer, according to measurement requirements.

[0060] Figure 2 This application provides an example of a block diagram of a measurement system for transmitting parameters in a vector network analyzer, such as... Figure 2 The multilayer dielectric material thickness measurement system based on TDR in this example mainly includes a vector network analyzer, a low-noise amplifier, a circulator, an antenna, a focusing lens, cables, and a metal calibration plate. The antenna module includes an antenna and a focusing lens. The antenna is used to receive and transmit microwave pulses. The focusing lens is positioned in the microwave pulse propagation path of the antenna to focus the microwave pulses transmitted by the antenna, thereby enhancing the signal strength incident on the multilayer dielectric material under test. The circulator port of the circulator is connected to a short calibration component, and a direct-pass calibration is performed in the vector network analyzer to form a direct signal path from the vector network analyzer (transmitter) to each stage of the device, then to the circulator, then to each stage of the device, and finally to the vector network analyzer (receiver).

[0061] The process of testing the wall thickness of a material using the aforementioned TDR-based multilayer dielectric material thickness measurement system includes:

[0062] S11: Obtain samples of each layer of dielectric material and measure the relative permittivity of each layer.

[0063] For example, a coaxial probe of a VNA can be pressed tightly against the surface of the multilayer dielectric material under test to measure the reflection coefficient, and the relative permittivity of the material can be calculated based on the reflection coefficient. Alternatively, scattering parameters at both ends of the multilayer dielectric material can be collected, and the reflection and transmission characteristics of electromagnetic waves in the sample can be deduced to obtain the relative permittivity of the material. Other methods commonly used in the art can also be used, and this embodiment is not limited thereto.

[0064] S12: Set the application frequency range of the vector network analyzer according to the properties of the multilayer dielectric material to be tested.

[0065] For example, user input is received, and for measuring wall thickness of low-loss plastics, a high-frequency range (e.g., 8.2 GHz - 12.4 GHz) is set. For measuring wall thickness of high-loss wet wood, a low-frequency range (e.g., 2 GHz - 4 GHz) is set.

[0066] S13: Use a through calibration component to perform through calibration on the circulator based on the application frequency range.

[0067] For example, a start frequency and an end frequency are set, the VNA calculates the frequency step to obtain multiple discrete frequency points, a pass-through calibration is performed at the connection between the antenna and the circulator, the VNA performs measurements at these discrete frequency points in sequence, and stores and corrects the error corresponding to each frequency point.

[0068] S14: The vector network analyzer emits microwave pulses to the multilayer dielectric material under test at the set frequency.

[0069] For example, the vector network analyzer responds to user input by switching to time-domain mode, or sets parameters such as the sweep frequency interval and pulse width (e.g., pulse width 30ns, period 100ns) based on environmental parameters (e.g., the estimated thickness of the material being measured).

[0070] S15: The circulator separates the microwave pulses emitted by the vector network analyzer from other signals, avoiding microwave pulse loss.

[0071] S16: The antenna receives and transmits microwave pulses, and the focusing lens focuses the microwave pulses transmitted by the antenna to enhance the microwave pulses.

[0072] S17: The antenna receives and transmits reflected waves from the multilayer dielectric material under test to the circulator.

[0073] S18: The circulator separates reflected waves from other signals, such as reflected waves and microwave pulses emitted by the vector network analyzer, to avoid loss of the emitted wave.

[0074] S19: A low-noise amplifier is used to amplify the reflected wave with low noise.

[0075] S20: The vector network analyzer performs a frequency domain scan on the reflected wave, acquires the frequency domain signal focused by the antenna module, performs a fast Fourier transform on the frequency domain signal to obtain the time domain signal. The reflected wave peak generated by the metal calibration plate is marked in the time domain signal, and the reflected wave peak is used as the starting point of the first layer of the multilayer dielectric material under test. The thickness parameters of each layer of material are calculated based on the relative permittivity.

[0076] This application also provides an example of the specific implementation process of step S20 performed by a vector network analyzer:

[0077] S201: Mark the start time of the first reflection peak in the time-domain signal;

[0078] S202: Determine the starting position of the first layer of the multilayer dielectric material to be tested based on the starting time, take the ending position of the previous layer as the starting position of the current layer, calculate the difference between the starting and ending positions of the current layer, and output the thickness parameters of each layer.

[0079] Specifically, S202 can be executed using a calculation module built based on formula (1);

[0080] (1);

[0081] = , Represents the relative permittivity of the i-th dielectric layer. , This represents the time of the i-th reflection peak displayed in the time domain signal. It represents the speed of light.

[0082] Figure 3 This is a schematic diagram of a time-domain signal obtained by processing a reflected wave, as an example of this application. The vertical axis represents the amplitude ratio dimension, and the horizontal axis represents the time dimension. Figure 3 The coordinates of peak 1 are (830.000ps, -9.99dB), and the coordinates of peak 2 are (1.480ns, -22.98dB). Figure 3 This is merely an example of detecting time-domain signals; peak parameters will not be listed individually.

[0083] Figure 4 This is a schematic diagram of an example multilayer dielectric material to be tested according to this application, such as... Figure 4 As shown, This is the interface between air and the first layer of medium. This is the interface between the first and second media layers, and so on for subsequent interfaces.

[0084] refer to Figure 1 and Figure 2 The process of executing S202 according to formula (1) includes:

[0085] (1);

[0086] (2);

[0087] (3);

[0088] (4);

[0089] in, Indicates the thickness of the i-th dielectric layer. Represents the speed of light. Represents the relative permittivity of the i-th dielectric layer. , This represents the time of the i-th reflection peak displayed in the time domain signal. This represents the spacing of the i-th layer of medium in the time domain. This indicates the position of the i-th peak displayed in the time domain. This represents the transmission speed factor of the i-th type of medium material.

[0090] The multilayer dielectric material thickness measurement system based on TDR proposed in this application embodiment can be flexibly constructed according to the loss, number of layers, thickness and detection method of the material being measured. When the loss of the material being measured is small, the material thickness is thin and the material has few layers, a vector network analyzer, antenna or circulator can be directly used for measurement.

[0091] Figure 5 This application provides an example of a block diagram of a system for measuring reflection parameters of a vector network analyzer, such as... Figure 5 The multilayer dielectric material thickness measurement system based on TDR in this example mainly includes a vector network analyzer, a combiner, a low-noise amplifier, a circulator, an antenna, a focusing lens, cables, and a metal calibration plate. The antenna module includes an antenna and a focusing lens. The antenna is used to receive and transmit microwave pulses. The focusing lens is positioned on the microwave pulse propagation path of the antenna to focus the microwave pulses transmitted by the antenna, thereby enhancing the signal strength incident on the multilayer dielectric material under test. The circulator port is equipped with a single-port calibration component. Single-port calibration at the coaxial port of the antenna or the coaxial port of the circulator can eliminate the loss and time delay effects of the reflection path (including the combiner, low-noise amplifier, and circulator). The combiner is connected to the low-noise amplifier, and the low-noise amplifier is connected to the circulator, forming a signal processing and enhancement link.

[0092] The combiner is used to combine multiple microwave pulses emitted by the vector network analyzer to obtain an enhanced incident signal.

[0093] In the aforementioned signal processing and enhancement link, the combiner combines multiple incident signals into one, increasing the energy incident on the material. The circulator isolates the LNA from the incident path, ensuring that the incident signal can be transmitted to the antenna in a low-loss manner. The low-noise amplifier amplifies the reflected wave signal, increasing the reflected signal to a boundary value that the VNA can recognize and calculate.

[0094] The process of testing the wall thickness of a material using the aforementioned TDR-based multilayer dielectric material thickness measurement system includes:

[0095] S31: Obtain samples of each layer of dielectric material and measure the relative permittivity of each layer.

[0096] For example, a coaxial probe of a VNA can be pressed tightly against the surface of the multilayer dielectric material under test to measure the reflection coefficient, and the relative permittivity of the material can be calculated based on the reflection coefficient. Alternatively, scattering parameters at both ends of the multilayer dielectric material can be collected, and the reflection and transmission characteristics of electromagnetic waves in the sample can be deduced to obtain the relative permittivity of the material. Other methods commonly used in the art can also be used, and this embodiment is not limited thereto.

[0097] S32: Set the application frequency range of the vector network analyzer according to the properties of the multilayer dielectric material to be tested.

[0098] For example, user input is received, and for measuring wall thickness of low-loss plastics, a high-frequency range (e.g., 10-20 GHz) is set. For measuring wall thickness of high-loss wet wood, a low-frequency range (e.g., 1-10 kHz) is set.

[0099] S33: Use a through calibration component to perform through calibration of the circulator based on the application frequency range.

[0100] For example, a start frequency and an end frequency are set, the VNA calculates the frequency step to obtain multiple discrete frequency points, a pass-through calibration is performed at the connection between the antenna and the circulator, the VNA performs measurements at these discrete frequency points in sequence, and stores and corrects the error corresponding to each frequency point.

[0101] S34: The vector network analyzer emits microwave pulses to the multilayer dielectric material under test at the set frequency.

[0102] S35: The combiner combines multiple microwave pulse signals emitted by the vector network analyzer into a single signal.

[0103] S36: The circulator separates the microwave pulses emitted by the vector network analyzer from other signals, avoiding microwave pulse loss.

[0104] S37: The antenna receives and transmits microwave pulses, and the focusing lens focuses the microwave pulses transmitted by the antenna to enhance the microwave pulses.

[0105] S38: The antenna receives and transmits reflected waves from the multilayer dielectric material under test to the circulator.

[0106] S39: The circulator separates reflected waves from other signals, such as reflected waves and microwave pulses emitted by the vector network analyzer, to avoid loss of the emitted wave.

[0107] S40: A low-noise amplifier is used to amplify the reflected wave with low noise.

[0108] S41: The vector network analyzer performs a frequency domain scan on the reflected wave, acquires the frequency domain signal focused by the antenna module, performs a fast Fourier transform on the frequency domain signal to obtain the time domain signal. The reflected wave peak generated by the metal calibration plate is marked in the time domain signal, and the reflected wave peak is used as the starting point of the first layer of the multilayer dielectric material under test. The thickness parameters of each layer of material are calculated based on the relative permittivity.

[0109] The TDR-based multilayer dielectric material thickness measurement system proposed in this invention transmits radio frequency time-domain microwave pulses to the multilayer dielectric material via a vector network analyzer. A signal enhancement link, constructed using a combiner, low-noise amplifier, and circulator, is built to achieve accurate signal transmission and acquisition. The vector network analyzer then scans the frequency domain signal reflected from the multilayer dielectric material, converting it into a time domain signal. Based on a VNA, the TDR technology functionality is realized. Using this TDR technology, the starting position of the first layer of material is located through calibration with a metal calibration plate, and then the material thickness is calculated layer by layer. Through the above calculation of the time domain signal, real-time measurement of the thickness of multilayer dielectric materials in a non-destructive, non-contact environment is achieved. This measurement system overcomes the shortcomings of traditional ultrasonic thin-film measurement methods, optical methods, and eddy current methods. It has a simple structure, is easy to build and implement, and has high measurement accuracy. It can be used for thickness measurement of multilayer furnace walls, multilayer conveying pipelines, and multilayer corrosion-resistant containers in industrial applications. It can also be used for thickness detection of multilayer dielectric materials in long-term industrial environments, providing a foundation for real-time wall thickness monitoring and penetration warning alerts.

[0110] For example, an alarm module can be set up so that when the vector network analyzer detects that the thickness of a specific layer in the multilayer dielectric material under test is less than a critical value, it outputs an alarm signal.

[0111] Example 2

[0112] Based on the TDR-based multilayer dielectric material thickness measurement system provided in Embodiment 1 of this application, correspondingly, Embodiment 2 of this application also provides a TDR-based multilayer dielectric material thickness measurement method. Figure 6 This is a flowchart illustrating the steps of the TDR-based method for measuring the thickness of multilayer dielectric materials proposed in this application. Figure 6 As shown, the vector network analyzer applied to the TDR-based multilayer dielectric material thickness measurement system proposed in Example 1 follows these steps:

[0113] S601: Acquires the frequency domain signal focused by the antenna module, performs a fast Fourier transform on the frequency domain signal to obtain the time domain signal.

[0114] S602: Extract the time of the reflection peak in each time domain and calculate it to obtain the thickness parameters of each layer of the multilayer dielectric material to be tested.

[0115] Optionally, the time of the reflection peak in each time domain is extracted and calculated to obtain the thickness parameters of each layer in the multilayer dielectric material under test, including:

[0116] Mark the start time of the first reflection peak in the time-domain signal;

[0117] The starting position of the first layer of the multilayer dielectric material to be tested is determined by the starting time. The ending position of the previous layer is used as the starting position of the current layer. The difference between the starting and ending positions of the current layer is calculated, and the thickness parameters of each layer are output.

[0118] Optionally, the method further includes:

[0119] Samples of each layer of dielectric material were obtained, and the relative permittivity of each layer of the multilayer dielectric material to be tested was detected.

[0120] The time of the reflection peak in each time domain is extracted and calculated to obtain the thickness parameters of each layer in the multilayer dielectric material under test, including:

[0121] The relative permittivity is substituted into the set calculation module, and the time of the reflection peak in each time domain is extracted for calculation to obtain the thickness parameters of each layer of the multilayer dielectric material to be tested; wherein, the calculation module performs the calculation according to formula (1);

[0122] (1);

[0123] = , Represents the relative permittivity of the i-th dielectric layer. , This represents the time of the i-th reflection peak displayed in the time domain signal. It represents the speed of light.

[0124] Optionally, the method further includes:

[0125] Acquire samples of each layer of dielectric material and set the frequency range of the vector network analyzer according to the dielectric material.

[0126] The circulator is calibrated both via and single-port within the specified frequency range.

[0127] The specific principles and execution processes of each unit and / or step in the TDR-based multilayer dielectric material thickness measurement method disclosed in Embodiment 2 of this application can be found in the corresponding parts of the TDR-based multilayer dielectric material thickness measurement system disclosed in Embodiment 1 of this application, and will not be repeated here.

[0128] Example 3

[0129] Embodiment 3 of this application provides a vector network analyzer, including: a processor and a memory, the processor and the memory being connected via a communication bus; wherein, the processor is used to call and execute a program stored in the memory; the memory is used to store the program, the program being used to implement the multilayer dielectric material thickness measurement method based on TDR as provided in Embodiment 1 of this application.

[0130] Example 4

[0131] Embodiment 4 of this application provides a computer-readable storage medium storing computer-executable instructions for performing a TDR-based multilayer dielectric material thickness measurement method as provided in Embodiment 1 of this application.

[0132] Those skilled in the art will further recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computing software, or a combination of both. To clearly illustrate the interchangeability of hardware and software, the components and steps of the various examples have been generally described in terms of functionality in the foregoing description. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0133] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of the invention.

[0134] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A multilayer dielectric material thickness measurement system based on TDR, characterized in that, The system includes: a vector network analyzer, an antenna module, and a metal calibration plate; wherein... The vector network analyzer is used to emit microwave pulses to the multilayer dielectric material under test at a set frequency. The antenna module is used to focus the reflected wave generated by the microwave pulse through the multilayer dielectric material under test; The metal calibration plate is disposed on the starting layer of the multilayer dielectric material to be tested, and is used to generate the first corresponding time-domain signal reflection peak when the microwave pulse is incident, so as to locate the starting position of the multilayer dielectric material. The vector network analyzer is also used to acquire frequency domain signals focused by the antenna module, perform fast Fourier transform on the frequency domain signals to obtain time domain signals, calculate the time domain signals according to the starting position, and output the thickness parameters of each layer of the multilayer dielectric material under test.

2. The multilayer dielectric material thickness measurement system based on TDR according to claim 1, characterized in that, The system also includes: a low-noise amplifier and a circulator; The circulator is used to separate the microwave pulse and the reflected wave generated by the multilayer dielectric material under test, so as to optimize the microwave pulse and the reflected wave and ensure low-loss propagation of the microwave pulse and the reflected wave; The low-noise amplifier is used to amplify the reflected wave with low noise.

3. The multilayer dielectric material thickness measurement system based on TDR according to claim 2, characterized in that, The system also includes a combiner; the combiner is connected to a low-noise amplifier, and the low-noise amplifier is connected to a circulator, forming a signal processing and enhancement link; The combiner is used to combine multiple microwave pulses emitted by the vector network analyzer to obtain an enhanced incident signal.

4. The multilayer dielectric material thickness measurement system based on TDR according to claim 1, characterized in that, The antenna module includes an antenna and a focusing lens; The antenna is used to receive and transmit microwave pulses; The focusing lens is disposed on the microwave pulse propagation path of the antenna and is used to focus the microwave pulse emitted by the antenna to enhance the signal strength incident on the multilayer dielectric material under test.

5. The multilayer dielectric material thickness measurement system based on TDR according to claim 2, characterized in that, The circulator port is provided with a through calibration element for through calibration of the circulator.

6. The multilayer dielectric material thickness measurement system based on TDR according to claim 2, characterized in that, The circulator port is equipped with a single-port calibration element for single-port calibration of the circulator.

7. A method for measuring the thickness of multilayer dielectric materials based on TDR, characterized in that, A vector network analyzer applied to the TDR-based multilayer dielectric material thickness measurement system according to any one of claims 1-6, the method comprising: The frequency domain signal focused by the antenna module is acquired, and a fast Fourier transform is performed on the frequency domain signal to obtain the time domain signal; The time of the reflection peak in each time domain is extracted and calculated to obtain the thickness parameters of each layer of the multilayer dielectric material to be tested.

8. The method for measuring the thickness of multilayer dielectric materials based on TDR according to claim 7, characterized in that, The time of the reflection peak in each time domain is extracted and calculated to obtain the thickness parameters of each layer in the multilayer dielectric material under test, including: Mark the start time of the first reflection peak in the time-domain signal; The starting position of the first layer of the multilayer dielectric material to be tested is determined by the starting time. The ending position of the previous layer is used as the starting position of the current layer. The difference between the starting and ending positions of the current layer is calculated, and the thickness parameters of each layer are output.

9. The method for measuring the thickness of multilayer dielectric materials based on TDR according to claim 7, characterized in that, The method further includes: Samples of each layer of dielectric material were obtained, and the relative permittivity of each layer of the multilayer dielectric material to be tested was detected. The time of the reflection peak in each time domain is extracted and calculated to obtain the thickness parameters of each layer in the multilayer dielectric material under test, including: The relative permittivity is substituted into the set calculation module, and the time of the reflection peak in each time domain is extracted for calculation to obtain the thickness parameters of each layer of the multilayer dielectric material to be tested; wherein, the calculation module performs the calculation according to formula (1); （1）； = , Represents the relative permittivity of the i-th dielectric layer. , This represents the time of the i-th reflection peak displayed in the time domain signal. It represents the speed of light.

10. The method for measuring the thickness of multilayer dielectric materials based on TDR according to claim 7, characterized in that, The method further includes: Acquire samples of each layer of dielectric material and set the frequency range of the vector network analyzer according to the dielectric material. The circulator is calibrated both via and single-port within the specified frequency range.

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