Thin film material electromagnetic parameter testing device and method based on transmission reflection method

Abstract

The invention provides a thin film material electromagnetic parameter testing device and method based on a transmission reflection method, and belongs to the technical field of microwave and millimeter wave material electromagnetic parameter testing. According to the device, a rectangular waveguide and a waveguide coaxial converter are used as main structures of a transmission / reflection method testing system, and components such as a supporting component and a pressing component are used as auxiliary components, so that the dielectric property of materials such as light, ultrathin and easily-deformed thin films can be tested. Meanwhile, according to the structural characteristics of the device, a reflection model of electromagnetic waves is deduced in a targeted manner and is used for reversely solving the dielectric constant of the sample to be detected.

Description

Technical Field

[0001] The present invention belongs to the technical field of microwave and millimeter wave material electromagnetic parameter testing, and in particular relates to a thin film material electromagnetic parameter testing device and method based on a transmission reflection method. Background Art

[0002] The new generation of materials is the foundation of the electronic information industry and one of the key cores of disruptive technological breakthroughs in the field of electronic science. Thin film materials are widely used in the electronic information industry and are key materials in important fields such as 5G communications, 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 indispensable and important task.

[0003] In the 1970s, an electromagnetic property measurement technology was developed based on transmission line theory and microwave network theory, namely the transmission / reflection method, also known as the NRW method. In this measurement method, the medium sample to be measured is placed in the internal area of ​​a transmission line such as a waveguide, coaxial line, microstrip line or stripline. The electromagnetic wave will be reflected and transmitted on the surface of the sample to be measured, which will cause amplitude attenuation and phase shift in the electromagnetic wave transmission process. According to these phenomena, combined with the relationship between the electromagnetic wave reflection and transmission parameters and the electromagnetic properties of the sample to be measured, the electromagnetic properties such as the magnetic permeability and complex dielectric constant of the sample to be measured can be extracted. Wang Chuang et al. proposed a material high-temperature transmission reflection method material measurement clamping device (CN213903655U), which mainly uses a rectangular waveguide as a transmission line, supplemented by a matching fixture and control device, etc., to achieve material electromagnetic parameter measurement.

[0004] However, due to the difficulty of fixing and preserving the shape of materials, as well as the limitations of basic test theory and algorithm accuracy, the traditional transmission / reflection method cannot guarantee the accuracy of testing ultra-thin or flexible materials. How to design a test device based on the physical properties of lightweight, ultra-thin and easily deformable materials and accurately test their electromagnetic properties has become an urgent problem that needs to be solved. Summary of the invention

[0005] In view of the problems existing in the background technology, the purpose of the present invention is to provide a device and method for testing electromagnetic parameters of thin film materials based on the transmission reflection method. The device uses a rectangular waveguide and a waveguide coaxial converter as the main structure of the transmission / reflection method test system, supplemented by supporting and pressing components, so as to achieve the dielectric property test of lightweight, ultra-thin and easily deformable thin films and other materials. At the same time, according to the structural characteristics of the device, the present invention specifically derives the reflection model of electromagnetic waves for inverse analysis of the dielectric constant of the sample to be tested.

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

[0007] A thin film material electromagnetic parameter testing device based on a transmission reflection method, comprising 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 pressing member 6, a second pressing member 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 lofted 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 implement electromagnetic data testing, reading, and storage, and the computer is used to implement dielectric constant calculation based on the electromagnetic data.

[0010] The first pressing member 6 is arranged in the first rectangular waveguide 1, the second pressing member 7 is arranged in the second rectangular waveguide 2, and the film 10 to be tested is placed between the first pressing member 6 and the second pressing member 7. The first pressing member 6 or the second pressing member 7 is adjusted to make the first pressing member 6 and the second pressing member 7 close to each other, so that the film is flat, and the sample to be tested is placed in the sample waveguide 5.

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

[0012] Furthermore, the device for testing the dielectric constant of thin film materials also includes a fixture, which is arranged outside the waveguide and is used to fix or move the first pressing member 6 and move or fix the second pressing member 7.

[0013] Furthermore, one of the first rectangular waveguide 1 or the second rectangular waveguide 2 is fixed, and the other is movable, so as to facilitate sampling and placement of the film to be tested.

[0014] Furthermore, a gap is provided on the fixed rectangular waveguide, a first hole is provided on the movable rectangular waveguide, a ridge structure is provided on the clamping piece connected to the fixed rectangular waveguide, and the ridge and the gap cooperate with each other through a clamp to realize the movement of the clamping piece; a second hole is provided on the clamping piece connected to the movable rectangular waveguide, and the relative position of the clamping piece connected to the movable rectangular waveguide in the movable rectangular waveguide remains unchanged through the first hole and the second hole.

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

[0016] The present invention also provides a method for inverting 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 dielectric constant test device of the thin film material, and 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 film material to be tested in 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 two clamping members, and the clamping members are adjusted to make the film material to be tested flat;

[0019] Step 3. Use a computer-controlled vector network analyzer to test the film material to be tested and read the microwave network parameter S 21 , S 11 ;

[0020] Step 4. Through the network parameters S 21 , S 11 The relationship between the transmission coefficient and reflection coefficient at different positions is established to calculate the relative dielectric constant ε of the sample to be tested. s , electrical loss tangent tanδ ε and relative magnetic permeability μ s , magnetic loss tangent tanδ μ :

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

[0022]

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

[0024]

[0025] Among them, R0 is the reflection coefficient of the electromagnetic wave when it is vertically incident from the front air layer to the front clamping piece in space, R1 is the reflection coefficient of the electromagnetic wave when it is vertically incident from the front clamping piece to the sample to be tested in space, 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 piece, P2 is the transmission coefficient of the electromagnetic wave in the sample to be tested, P3 is the transmission coefficient of the electromagnetic wave in the rear clamping piece, 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] During the propagation process, electromagnetic waves will produce phase shift, attenuation and other changes, which are related to the electromagnetic parameters and losses of the propagation medium. According to the characteristics of lightweight, ultra-thin and easily deformable materials, the present invention innovatively proposes a dielectric constant test device for thin film materials based on the transmission reflection method, and designs a special test fixture structure to make the film to be tested flat and non-deformed during the test. The propagation path of the electromagnetic wave successively appears evenly distributed air, compression parts, samples to be tested, compression parts and air, which reduces the influence of deformation-generated gaps on the test results, and reduces the error introduced by factors such as deformation of the samples to be tested; improves the accuracy of the test, which is conducive to the accurate analysis of the electromagnetic properties of thin film materials. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0029] Figure 2 It is a schematic diagram of the reflection model of electromagnetic waves in the electromagnetic parameter testing device of thin film materials of the present invention.

[0030] Figure 3 This is a schematic diagram of a thin film material electromagnetic parameter testing device according to Example 1 of the present invention.

[0031] Figure 4 This is a physical picture of the electromagnetic parameter testing device of thin film material according to Example 1 of the present invention.

[0032] Figure 5 The flowchart of the electromagnetic parameter inversion method of lightweight thin film materials based on the transmission reflection method in the present invention.

[0033] Figure 6 These are the electromagnetic property test data of the fiber reinforced plastic sample of Example 2 of the present invention.

[0034] Figure 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 pressing member, 7 is the second pressing member, 8 is the vector network analyzer, 9 is the computer, and 10 is the thin film material to be tested. DETAILED DESCRIPTION

[0035] In order to make the objectives, technical solutions and advantages of the present invention more clear, the present invention is further described in detail below in conjunction with the implementation modes and the accompanying drawings.

[0036] A device for testing electromagnetic parameters of thin film materials based on transmission reflection method, the overall structure diagram of the device is as follows 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 pressing member 6, a second pressing member 7, a vector network analyzer 8, a computer 9 and a matching fixture (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 lofted 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 implement electromagnetic data testing, reading, and storage, and the computer is used to implement dielectric constant calculation based on the electromagnetic data.

[0039] The first pressing member 6 is arranged in the first rectangular waveguide 1, the second pressing member 7 is arranged in the second rectangular waveguide 2, the film 10 to be tested is placed between the first pressing member 6 and the second pressing member 7, and the first pressing member 6 or the second pressing member 7 is adjusted to make the first pressing member 6 and the second pressing member 7 close to each other, so as to make the film flat;

[0040] The matching fixture is arranged outside the waveguide, and is used to fix or move the first pressing member 6 or the second pressing member 7; one of the first rectangular waveguide 1 or the second rectangular waveguide 2 is fixed, and the other is movable, so as to facilitate the sampling and placement of the film to be tested;

[0041] A gap is provided on the fixed rectangular waveguide, a first hole is provided on the movable rectangular waveguide, a ridge structure is provided on the clamping piece connected to the fixed rectangular waveguide, and the ridge and the gap cooperate with each other through a clamp to realize the movement of the clamping piece; a second hole is provided on the clamping piece connected to the movable rectangular waveguide, and the relative position of the clamping piece connected to the movable rectangular waveguide in the movable rectangular waveguide remains unchanged through the first hole and the second hole.

[0042] Figure 2The figure is a schematic diagram of the reflection model of electromagnetic waves in the dielectric constant test device of the thin film material of the present invention. Based on the characteristics of the thin film material being light, ultra-thin and easy to deform, the present invention designs a clamping member in the waveguide structure, and the clamping member ensures the flatness of the thin film material during the test. The electromagnetic wave emitted from one port of the vector network analyzer is transmitted in the waveguide through the waveguide coaxial converter. In the propagation path of the electromagnetic wave, uniformly distributed air, a clamping member, a sample to be tested, a clamping member and air appear in sequence. Because the environment before and after the sample to be tested is symmetrical and the same, the feasibility of the algorithm derivation and the accuracy of the test results are guaranteed. Therefore, the relative dielectric constant and relative magnetic permeability of the thin film material to be tested can be calculated based on the network parameters (S11, S21) measured by the vector network analyzer and the relevant parameters of the electromagnetic wave propagation in the medium.

[0043] Example 1

[0044] A device for testing electromagnetic parameters of thin film materials based on transmission reflection method, the overall structure diagram of the device is as follows 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 pressing member 6, a second pressing member 7, a vector network analyzer 8, a computer 9 and a matching fixture;

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

[0046] The matching fixture includes a horizontal base and a vertical arm fixedly arranged on the surface of the horizontal base; the first rectangular waveguide 1 is fixedly connected to the vertical arm, and a gap is arranged on the vertical arm to fix the rectangular waveguide, and a ridge is arranged on the first clamping member 6, and the ridge is arranged in the gap, and the first clamping member is driven to move in the waveguide by sliding the ridge on the gap; a slide rail is arranged at the upper end of the vertical arm, and the second rectangular waveguide 2 is arranged on the slide rail, and sampling and lofting are realized by moving the second rectangular waveguide 2 on the slide rail; an opening is arranged at the lower side edge of the second rectangular waveguide 2, and the position of the second clamping member 7 is fixed by the opening; the first clamping member 6 is moved to make the first clamping member 6 and the second clamping member 7 close to each other, so that the film between the two is placed flat;

[0047] The coaxial line connection end of the first waveguide-to-coaxial converter 3 is connected to the first port of the vector network analyzer, and the coaxial line connection end of the second waveguide-to-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 implement electromagnetic data testing, reading, and storage, and the computer is used to implement dielectric constant calculation based on the electromagnetic data;

[0049] The actual picture of this embodiment is as follows Figure 4 shown.

[0050] Example 2

[0051] The present invention also provides a method for inverting electromagnetic parameters of thin film materials. The flowchart of the method is as follows: Figure 5 As shown, the following steps are included:

[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 dielectric constant test device of the thin film material, and 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, and place the fiber reinforced plastic sample to be tested between 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 parameter S 21 , S 11 ;

[0055] Step 4. Through the network parameters S 21 , S 11 The equations are established with the relationship between the transmission coefficient and the reflection coefficient at different positions to calculate the relative dielectric constant ε of the fiber reinforced plastic sample to be tested. s , electrical loss tangent tanδ ε and relative magnetic permeability μ s , magnetic loss tangent tanδ μ ;

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

[0057]

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

[0059]

[0060] Among them, R0 is the reflection coefficient of the electromagnetic wave when it is vertically incident from the front air layer to the front clamping piece in space, R1 is the reflection coefficient of the electromagnetic wave when it is vertically incident from the front clamping piece to the sample to be tested in space, 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 piece, P2 is the transmission coefficient of the electromagnetic wave in the sample to be tested, P3 is the transmission coefficient of the electromagnetic wave in the rear clamping piece, 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 electromagnetic parameters and physical parameters of the sample to be tested.

[0061] Figure 6 The electromagnetic properties test data curve of the fiber reinforced plastic sample of this embodiment is shown in FIG. As can be seen from the figure, the test device and method of the present invention can test and obtain the relative dielectric constant ε of the sample. s , electrical loss tangent tanδ ε , relative magnetic permeability μ s and magnetic loss tangent tanδ μ , verifying the feasibility of the device and method.

[0062] The above description is only a specific implementation mode of the present invention. Any feature disclosed in this specification, unless otherwise stated, can be replaced by other alternative features that are equivalent or have similar purposes; all the disclosed features, or all the steps in the methods or processes, except for mutually exclusive features and / or steps, can be combined in any way.

Claims

1. A thin film material electromagnetic parameter testing device based on transmission reflection method, characterized in that: 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 pressing member 6, a second pressing member 7, a vector network analyzer 8 and a computer 9; Among them, the waveguide connection end of the first waveguide-coaxial converter 3, the first rectangular waveguide 1, the lofted 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; The computer is connected to a vector network analyzer; the vector network analyzer is used to implement electromagnetic data testing, reading, and storage, and the computer is used to implement dielectric constant calculation based on the electromagnetic data; The first pressing member 6 is arranged in the first rectangular waveguide 1, the second pressing member 7 is arranged in the second rectangular waveguide 2, and the film 10 to be tested is placed between the first pressing member 6 and the second pressing member 7. The first pressing member 6 or the second pressing member 7 is adjusted to make the first pressing member 6 and the second pressing member 7 close to each other, so that the film is flat, and the sample to be tested is placed in the sample waveguide 5.

2. The thin film material electromagnetic parameter testing device according to claim 1, characterized in that: The first pressing member 6 and the second pressing member 7 are both made of non-metallic materials with known electromagnetic parameters, and have the same size.

3. The thin film material electromagnetic parameter testing device according to claim 1, characterized in that: The device for testing the dielectric constant of thin film materials further comprises a fixture, which is arranged outside the waveguide and is used to fix or move the first pressing member 6 and move or fix the second pressing member 7 .

4. The thin film material electromagnetic parameter testing device according to claim 1, characterized in that: One of the first rectangular waveguide 1 or the second rectangular waveguide 2 is fixed, and the other is movable, so as to facilitate the sampling and placement of the film to be tested.

5. The thin film material electromagnetic parameter testing device according to claim 4, characterized in that: A gap is provided on the fixed rectangular waveguide, a first hole is provided on the movable rectangular waveguide, a ridge structure is provided on the pressing piece connected to the fixed rectangular waveguide, and the ridge and the gap are matched through a clamp to realize the movement of the pressing piece; A second hole is arranged on the pressing piece connected to the movable rectangular waveguide, and the relative position of the pressing piece 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 according to claim 1, characterized in that: The first waveguide-coaxial converter 3 and the second waveguide-coaxial converter 4 both have orthogonal structures.

7. An inversion method based on the thin film material electromagnetic parameter testing device according to any one of claims 1 to 6, characterized in that: The steps include: Step 1. Connect the test device, use a vector network analyzer to perform TRL calibration on the test device, and 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 in 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 two clamping members, and the clamping members are adjusted to make the film material to be tested flat; Step 3. Use a computer-controlled vector network analyzer to test the film material to be tested and read the microwave network parameter S 21 , S 11 ; Step 4. Through the network parameters S 21 , S 11 The relationship between the transmission coefficient and reflection coefficient at different positions is established to calculate the relative dielectric constant ε of the sample to be tested. s , electrical loss tangent tanδ ε and relative magnetic permeability μ s , magnetic loss tangent tanδ μ : Among them, the network parameter S 11 The relationship between the transmission coefficient and reflection coefficient at different positions is: Network parameter S 21 The relationship between the transmission coefficient and reflection coefficient at different positions is: Among them, R0 is the reflection coefficient of the electromagnetic wave when it is vertically incident from the front air layer to the front clamping piece in space, R1 is the reflection coefficient of the electromagnetic wave when it is vertically incident from the front clamping piece to the sample to be tested in space, 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 piece, P2 is the transmission coefficient of the electromagnetic wave in the sample to be tested, P3 is the transmission coefficient of the electromagnetic wave in the rear clamping piece, and T2 is the transmission coefficient of the electromagnetic wave in the rear air.

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