An apparatus and method for testing electromagnetic parameters of thin film materials based on the transmission-reflection method.

Abstract

This invention provides a device and method for testing the electromagnetic parameters of thin film materials based on the transmission-reflection method, belonging to the technical field of electromagnetic parameter testing for microwave and millimeter-wave materials. The device uses a rectangular waveguide and a waveguide-coaxial converter as the main structure of the transmission / reflection method testing system, supplemented by supporting and clamping components, thereby enabling the testing of the dielectric properties of lightweight, ultra-thin, and easily deformable thin films and other materials. Simultaneously, based on the structural characteristics of the device, this invention specifically derives an electromagnetic wave reflection model for inverse solving of the dielectric constant of the sample under test.

Description

Technical Field

[0001] This invention belongs to the field of electromagnetic parameter testing technology for microwave and millimeter-wave materials, specifically relating to a device and method for testing electromagnetic parameters of thin film materials based on the transmission reflection method. Background Technology

[0002] Next-generation materials are the foundation of the electronics and information industry and one of the key core technologies for disruptive breakthroughs in electronic science. Thin film materials are widely used in the electronics and information industry and are key materials in important fields such as 5G communication, COF modules, WPC Light-Bar modules, Multilayer modules, and Rigid-Flex modules. Evaluating the electromagnetic properties of lightweight and easily deformable thin film materials has become an essential and important task.

[0003] In the 1970s, an electromagnetic property measurement technique, known as the transmission / reflection method or NRW method, was developed based on transmission line theory and microwave network theory. In this method, the sample is placed inside a transmission line such as a waveguide, coaxial line, microstrip line, or stripline. Electromagnetic waves are reflected and transmitted across the sample surface, causing amplitude attenuation and phase shift during transmission. Based on these phenomena and the relationship between electromagnetic wave reflection and transmission parameters and the electromagnetic properties of the sample, electromagnetic properties such as permeability and complex permittivity can be extracted. The "A Material Measurement Clamping Device Using the High-Temperature Transmission / Reflection Method" (CN213903655U) proposed by Wang Chuang et al. primarily uses a rectangular waveguide as the transmission line, supplemented by matching fixtures and control devices, to achieve the measurement of material electromagnetic parameters.

[0004] However, due to difficulties in material fixation and shape preservation, as well as limitations in the accuracy of basic testing theories and algorithms, traditional transmission / reflection methods cannot guarantee the accuracy of testing ultrathin or flexible materials. Therefore, designing testing devices based on the physical properties of lightweight, ultrathin, and easily deformable materials to accurately test their electromagnetic properties has become an urgent problem to be solved. Summary of the Invention

[0005] To address the problems existing in the background technology, the present invention aims to provide a device and method for testing the electromagnetic parameters of thin film materials based on the transmission / reflection method. This device uses a rectangular waveguide and a waveguide-coaxial converter as the main structure of the transmission / reflection method testing system, supplemented by supporting and clamping components, thereby enabling the testing of the dielectric properties of lightweight, ultra-thin, and easily deformable thin films and other materials. Simultaneously, based on the structural characteristics of the device, the present invention specifically derives an electromagnetic wave reflection model for inverse solving of the dielectric constant of the sample under test.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows:

[0007] A device for testing electromagnetic parameters of thin film materials based on the transmission reflection method includes a first rectangular waveguide 1, a second rectangular waveguide 2, a first waveguide coaxial converter 3, a second waveguide coaxial converter 4, a lofting waveguide 5, a first clamping component 6, a second clamping component 7, a vector network analyzer 8, and a computer 9.

[0008] Among them, the waveguide connection end of the first waveguide coaxial converter 3, the first rectangular waveguide 1, the lofting waveguide 5, the second rectangular waveguide 2, and the second waveguide coaxial converter 4 are connected in sequence. The coaxial line connection end of the first waveguide coaxial converter 3 is connected to the first port of the vector network analyzer, and the coaxial line connection end of the second waveguide coaxial converter 4 is connected to the second port of the vector network analyzer.

[0009] The computer is connected to a vector network analyzer; the vector network analyzer is used to test, read, and store electromagnetic data, while the computer is used to calculate the dielectric constant based on the electromagnetic data.

[0010] The first clamping member 6 is disposed in the first rectangular waveguide 1, and the second clamping member 7 is disposed in the second rectangular waveguide 2. The film to be tested 10 is placed between the first clamping member 6 and the second clamping member 7. The first clamping member 6 or the second clamping member 7 is adjusted to make the first clamping member 6 and the second clamping member 7 fit tightly, so that the film is flat and the sample to be tested is placed in the sample laying waveguide 5.

[0011] Furthermore, both the first clamping member 6 and the second clamping member 7 are made of non-metallic materials with known electromagnetic parameters, and both have the same size.

[0012] Furthermore, the thin film material dielectric constant testing device also includes a clamp disposed outside the waveguide for fixing or moving the first clamping member 6 and moving or fixing the second clamping member 7.

[0013] Furthermore, one of the first rectangular waveguide 1 or the second rectangular waveguide 2 is fixed while the other is movable, which facilitates the sampling and placement of the thin film under test.

[0014] Furthermore, a slot is provided on the fixed rectangular waveguide, a first hole is provided on the movable rectangular waveguide, and a ridge structure is provided on the clamping member connected to the fixed rectangular waveguide. The fit between the ridge and the slot is achieved by a clamp, thereby enabling the movement of the clamping member. A second hole is provided on the clamping member connected to the movable rectangular waveguide. The relative position of the clamping member connected to the movable rectangular waveguide within the movable rectangular waveguide is kept constant through the first hole and the second hole.

[0015] Furthermore, both the first waveguide coaxial converter 3 and the second waveguide coaxial converter 4 are orthogonal structures.

[0016] This invention also provides a method for inverting the electromagnetic parameters of thin film materials, comprising the following steps:

[0017] Step 1. Connect the waveguide coaxial converter to the two ports of the vector network analyzer. Use the vector network analyzer to perform TRL calibration on the thin film material dielectric constant testing device. Move the calibration end face of the device to the interface between the waveguide coaxial converter and the rectangular waveguide.

[0018] Step 2. After calibration, place the thin film material to be tested into the lofting waveguide, connect the waveguide coaxial converter, the rectangular waveguide and the lofting waveguide. At this time, the thin film material to be tested is placed between the two clamping parts. Adjust the clamping parts to make the thin film material to be tested flat.

[0019] Step 3. Use a computer-controlled vector network analyzer to test the thin film material under test and read the microwave network parameters S. 21 S 11 ;

[0020] Step 4. Through network parameter S 21 S 11 An equation was established to relate the transmission coefficient and reflection coefficient at different locations, and the relative permittivity ε of the sample under test was calculated. s , tangent of electrical loss angle tanδ ε and relative permeability μ s Magnetic loss tangent tanδ μ :

[0021] Among them, network parameter S 11 The relationship between the transmission coefficient and reflection coefficient at different locations is as follows:

[0022]

[0023] Network parameter S 21 The relationship between the transmission coefficient and reflection coefficient at different locations is as follows:

[0024]

[0025] Wherein, R0 is the reflection coefficient when the electromagnetic wave is perpendicularly incident from the front air layer to the front clamping component, R1 is the reflection coefficient when the electromagnetic wave is perpendicularly incident from the front clamping component to the sample under test, T1 is the transmission coefficient of the electromagnetic wave in the front air, P1 is the transmission coefficient of the electromagnetic wave in the front clamping component, P2 is the transmission coefficient of the electromagnetic wave in the sample under test, P3 is the transmission coefficient of the electromagnetic wave in the rear clamping component, and T2 is the transmission coefficient of the electromagnetic wave in the rear air.

[0026] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0027] Electromagnetic waves undergo phase shifts and attenuation during propagation, changes related to the electromagnetic parameters and losses of the propagation medium. Based on the characteristics of lightweight, ultrathin, and easily deformable materials, this invention innovatively proposes a dielectric constant testing device for thin film materials based on the transmission-reflection method. A dedicated testing fixture structure is designed to ensure the tested film remains flat and deformation-free during testing. The propagation path of the electromagnetic wave sequentially includes uniformly distributed air, a clamping element, the tested sample, the clamping element, and air again, reducing the impact of deformation-induced voids on the test results and minimizing errors introduced by factors such as sample deformation. This improves testing accuracy and facilitates precise analysis of the electromagnetic properties of thin film materials. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the overall structure of the thin film material electromagnetic parameter testing device of the present invention.

[0029] Figure 2 This is a schematic diagram of the electromagnetic wave reflection model in the thin film material electromagnetic parameter testing device of the present invention.

[0030] Figure 3 This is a schematic diagram of the electromagnetic parameter testing device for thin film materials in Embodiment 1 of the present invention.

[0031] Figure 4 This is a physical image of the electromagnetic parameter testing device for thin film materials according to Embodiment 1 of the present invention.

[0032] Figure 5 This is a flowchart of the electromagnetic parameter inversion method for lightweight thin film materials based on the transmission reflection method in this invention.

[0033] Figure 6 The electromagnetic property test data are for the fiber-reinforced plastic sample of Example 2 of this invention.

[0034] Figure reference numerals: 1 is the first rectangular waveguide, 2 is the second rectangular waveguide, 3 is the first waveguide coaxial converter, 4 is the second waveguide coaxial converter, 5 is the lofting waveguide, 6 is the first clamping component, 7 is the second clamping component, 8 is the vector network analyzer, 9 is the computer, and 10 is the thin film material to be tested. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the embodiments and accompanying drawings.

[0036] A device for testing the electromagnetic parameters of thin film materials based on the transmission-reflection method is shown in the schematic diagram of its overall structure. Figure 1As shown, it includes a first rectangular waveguide 1, a second rectangular waveguide 2, a first waveguide coaxial converter 3, a second waveguide coaxial converter 4, a lofting waveguide 5, a first clamping component 6, a second clamping component 7, a vector network analyzer 8, a computer 9, and matching fixtures (not shown in the figure); the first waveguide coaxial converter 3 and the second waveguide coaxial converter 4 are both orthogonal structures;

[0037] Among them, the waveguide connection end of the first waveguide coaxial converter 3, the first rectangular waveguide 1, the lofting waveguide 5, the second rectangular waveguide 2, and the waveguide connection end of the second waveguide coaxial converter 4 are connected in sequence. The coaxial line connection end of the first waveguide coaxial converter 3 is connected to the first port of the vector network analyzer, and the coaxial line connection end of the second waveguide coaxial converter 4 is connected to the second port of the vector network analyzer.

[0038] The computer is connected to a vector network analyzer; the vector network analyzer is used to test, read, and store electromagnetic data, while the computer is used to calculate the dielectric constant based on the electromagnetic data.

[0039] The first clamping member 6 is disposed in the first rectangular waveguide 1, the second clamping member 7 is disposed in the second rectangular waveguide 2, the film to be tested 10 is placed between the first clamping member 6 and the second clamping member 7, and the first clamping member 6 or the second clamping member 7 is adjusted to make the first clamping member 6 and the second clamping member 7 fit tightly, thereby making the film flat.

[0040] The matching clamp is set outside the waveguide and is used to fix or move the first clamping member 6 or the second clamping member 7; one of the first rectangular waveguide 1 or the second rectangular waveguide 2 is fixed and the other is movable, which facilitates the sampling and placement of the film to be tested;

[0041] A slot is provided on a fixed rectangular waveguide, and a first hole is provided on a movable rectangular waveguide. A ridge structure is provided on a clamping component connected to the fixed rectangular waveguide. The fit between the ridge and the slot is achieved by a clamp, which enables the movement of the clamping component. A second hole is provided on the clamping component connected to the movable rectangular waveguide. The relative position of the clamping component connected to the movable rectangular waveguide in the movable rectangular waveguide is kept constant through the first hole and the second hole.

[0042] Figure 2This is a schematic diagram of the electromagnetic wave reflection model in the dielectric constant testing device for thin film materials of the present invention. Based on the lightweight, ultra-thin, and easily deformable characteristics of thin film materials, the present invention incorporates a clamping element in the waveguide structure to ensure the flatness of the thin film material during testing. Electromagnetic waves emitted from one port of the vector network analyzer are transmitted within the waveguide via a waveguide-coaxial converter. The propagation path of the electromagnetic wave sequentially includes uniformly distributed air, the clamping element, the sample under test, the clamping element again, and air again. Because the environment before and after the sample under test is symmetrical and identical, the feasibility of the algorithm derivation and the accuracy of the test results are ensured. Therefore, based on the network parameters (S11, S21) measured by the vector network analyzer and the relevant parameters of electromagnetic wave propagation in the medium, the relative permittivity and relative permeability of the thin film material under test can be calculated.

[0043] Example 1

[0044] A device for testing the electromagnetic parameters of thin film materials based on the transmission-reflection method is shown in the schematic diagram of its overall structure. Figure 3 As shown, it includes a first rectangular waveguide 1, a second rectangular waveguide 2, a first waveguide coaxial converter (orthogonal structure) 3, a second waveguide coaxial converter (orthogonal structure) 4, a lofting waveguide 5, a first clamping component 6, a second clamping component 7, a vector network analyzer 8, a computer 9, and matching fixtures;

[0045] The second waveguide coaxial converter (orthogonal structure) 4, the second rectangular waveguide 2, the lofting waveguide 5, the first rectangular waveguide 1 and the first waveguide coaxial converter 3 are connected sequentially from top to bottom;

[0046] The fixture includes a horizontal base and a vertical arm fixedly mounted on the surface of the horizontal base. A first rectangular waveguide 1 is fixedly connected to the vertical arm to fix the rectangular waveguide. A slot is provided on the first clamping member 6, which is located within the slot. The sliding of the ridge on the slot drives the first clamping member to move within the waveguide. A slide rail is provided at the upper end of the vertical arm, and a second rectangular waveguide 2 is mounted on the slide rail. Sampling and placement are achieved by moving the second rectangular waveguide 2 on the slide rail. An opening is provided at the lower edge of the second rectangular waveguide 2 to fix the position of the second clamping member 7. By moving the first clamping member 6, the first clamping member 6 and the second clamping member 7 are brought into close contact, thereby ensuring that the film between them is placed flat.

[0047] The coaxial cable connection end of the first waveguide coaxial converter 3 is connected to the first port of the vector network analyzer, and the coaxial cable connection end of the second waveguide coaxial converter 4 is connected to the second port of the vector network analyzer.

[0048] The computer is connected to a vector network analyzer; the vector network analyzer is used to perform electromagnetic data testing, reading, and storage, while the computer is used to calculate the dielectric constant based on the electromagnetic data.

[0049] The physical object diagram of this embodiment is as follows: Figure 4 As shown.

[0050] Example 2

[0051] This invention also provides a method for inverting the electromagnetic parameters of thin film materials, the flowchart of which is shown below. Figure 5 As shown, it includes the following steps:

[0052] Step 1. Connect the waveguide coaxial converter to the two ports of the vector network analyzer. Use the vector network analyzer to perform TRL calibration on the thin film material dielectric constant testing device. Move the calibration end face of the device to the interface between the waveguide coaxial converter and the rectangular waveguide.

[0053] Step 2. After calibration, place the fiber-reinforced plastic sample to be tested with a thickness of 0.15 mm into the lofting waveguide, connect the waveguide coaxial converter, the rectangular waveguide and the lofting waveguide. At this time, the fiber-reinforced plastic sample to be tested is placed between the two clamping parts. Adjust the clamping parts to make the fiber-reinforced plastic sample to be tested flat.

[0054] Step 3. Use a computer-controlled vector network analyzer to test the fiber-reinforced plastic sample and read the microwave network parameters S. 21 S 11 ;

[0055] Step 4. Through network parameter S 21 S 11 An equation was established to relate the transmission coefficient and reflection coefficient at different locations, and the relative permittivity ε of the fiber-reinforced plastic sample under test was calculated. s , tangent of electrical loss angle tanδ ε and relative permeability μ s Magnetic loss tangent tanδ μ ;

[0056] Among them, network parameter S 11 The relationship between the transmission coefficient and reflection coefficient at different locations is as follows:

[0057]

[0058] Network parameter S 21 The relationship between the transmission coefficient and reflection coefficient at different locations is as follows:

[0059]

[0060] Wherein, R0 is the reflection coefficient when the electromagnetic wave is perpendicularly incident from the front air layer to the front clamping component, R1 is the reflection coefficient when the electromagnetic wave is perpendicularly incident from the front clamping component to the sample under test, T1 is the transmission coefficient of the electromagnetic wave in the front air, P1 is the transmission coefficient of the electromagnetic wave in the front clamping component, P2 is the transmission coefficient of the electromagnetic wave in the sample under test, P3 is the transmission coefficient of the electromagnetic wave in the rear clamping component, and T2 is the transmission coefficient of the electromagnetic wave in the rear air. The aforementioned reflection coefficient and transmission coefficient can be expressed by information such as the electromagnetic parameters and physical parameters of the sample under test.

[0061] Figure 6 This is a graph showing the electromagnetic property test data of the fiber-reinforced plastic sample in this embodiment. As can be seen from the graph, the testing device and method of this invention can measure the relative permittivity ε of the sample. s , tangent of electrical loss angle tanδ ε Relative permeability μ s and magnetic loss tangent tanδ μ This verifies the feasibility of the device and method.

[0062] The above description is merely a specific embodiment of the present invention. Any feature disclosed in this specification may be replaced by other equivalent or similar features unless otherwise specified. All disclosed features, or steps in all methods or processes, may be combined in any way except for mutually exclusive features and / or steps.

Claims

1. A device for testing the electromagnetic parameters of thin film materials based on the transmission-reflection method, characterized in that, It includes a first rectangular waveguide, a second rectangular waveguide, a first waveguide coaxial converter, a second waveguide coaxial converter, a lofting waveguide, a first clamping component, a second clamping component, a vector network analyzer, and a computer; The waveguide connection end of the first waveguide coaxial converter, the first rectangular waveguide, the lofting waveguide, the second rectangular waveguide, and the waveguide connection end of the second waveguide coaxial converter are connected in sequence. The coaxial line connection end of the first waveguide coaxial converter is connected to the first port of the vector network analyzer, and the coaxial line connection end of the second waveguide coaxial converter is connected to the second port of the vector network analyzer. The computer is connected to a vector network analyzer; the vector network analyzer is used to perform electromagnetic data testing, reading, and storage, while the computer is used to calculate the dielectric constant based on the electromagnetic data. The first clamping member is disposed in the first rectangular waveguide, and the second clamping member is disposed in the second rectangular waveguide. The film to be tested is placed between the first clamping member and the second clamping member. The first clamping member or the second clamping member is adjusted to make the first clamping member and the second clamping member fit tightly together, thereby making the film flat and the sample to be tested placed in the sampling waveguide.

2. The thin film material electromagnetic parameter testing device as described in claim 1, characterized in that, Both the first and second clamping components are made of non-metallic materials with known electromagnetic parameters, and they are the same size.

3. The thin film material electromagnetic parameter testing device as described in claim 1, characterized in that, The thin film material electromagnetic parameter testing device also includes a clamp, which is disposed outside the waveguide and is used to fix or move the first clamping member and to move or fix the second clamping member.

4. The thin film material electromagnetic parameter testing device as described in claim 3, characterized in that, One of the first or second rectangular waveguides is fixed while the other is movable, which facilitates the sampling and placement of the thin film under test.

5. The thin film material electromagnetic parameter testing device as described in claim 4, characterized in that, A slit is provided on a fixed rectangular waveguide, a first hole is provided on a movable rectangular waveguide, and a ridge structure is provided on a clamping component connected to the fixed rectangular waveguide. The movement of the clamping component is achieved by the fit between the ridge and the slit through a clamp. A second hole is provided on the clamping member connected to the movable rectangular waveguide, and the relative position of the clamping member connected to the movable rectangular waveguide in the movable rectangular waveguide is kept unchanged through the first hole and the second hole.

6. The thin film material electromagnetic parameter testing device as described in claim 1, characterized in that, Both the first and second waveguide coaxial converters are orthogonal structures.

7. An inversion method based on the electromagnetic parameter testing device for thin film materials according to any one of claims 1-6, characterized in that, Includes the following steps: Step 1. Connect the test device and use a vector network analyzer to perform TRL calibration on the test device. Move the calibration end face of the test device to the interface between the waveguide coaxial converter and the rectangular waveguide. Step 2. After calibration, place the film material to be tested into the lofting waveguide, connect the waveguide coaxial converter, the rectangular waveguide and the lofting waveguide. At this time, the film material to be tested is placed between the two clamping parts. Adjust the clamping parts to make the film material to be tested flat. Step 3. Use a computer-controlled vector network analyzer to test the thin film material under test and read the microwave network parameters. S 21 , S 11 ; Step 4. Through network parameters S 21 , S 11 An equation was established to relate the transmission coefficient and reflection coefficient at different locations, and the relative permittivity of the sample under test was calculated. , electrical loss tangent and relative permeability Magnetic loss tangent ; Among them, network parameters S 11 The relationship between the transmission coefficient and reflection coefficient at different locations is as follows: Network parameters S 21 The relationship between the transmission coefficient and reflection coefficient at different locations is as follows: in, R 0 represents the reflection coefficient when an electromagnetic wave is incident perpendicularly from the front air layer to the front clamping component. R 1 represents the reflection coefficient when an electromagnetic wave is incident perpendicularly from the front clamping component to the sample under test. T 1 represents the transmission coefficient of the electromagnetic wave in the air at the front end. P 1 represents the transmission coefficient of electromagnetic waves in the front clamping component. P 2 represents the transmission coefficient of electromagnetic waves in the sample under test. P 3 represents the transmission coefficient of electromagnetic waves in the rear clamping component. T 2 represents the transmission coefficient of electromagnetic waves in the air at the rear end.

Images