Material center positioning method and system for dielectric property test of quasi-optical cavity material
By fitting the resonant frequency change curve in the double spherical quasi-optical cavity test system, the center position of the thin material is determined, and the problem that the center positioning error of the thin material affects the dielectric performance test accuracy is solved, and higher testing accuracy and accuracy are achieved.
Patent Information
- Application Number
- CN202411646894.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-18
- Publication Date
- 2025-02-25
AI Technical Summary
In the double-spherical quasi-optical cavity testing method, the center positioning error of the thin material will significantly affect the accuracy of the dielectric performance test, especially due to the large physical measurement error, which leads to an increase in the error of the test results.
By obtaining the placement position of the material to be tested in the double-spherical quasi-optical cavity testing system and the corresponding resonant frequency, fit the resonant frequency change curve, and extracting the placement position corresponding to the peak or trough as the center position of the material.
The accuracy of the dielectric performance test of double-spheric cavity materials is improved, especially in thin film material testing, which eliminates the error introduced by the center positioning offset of the material and improves the accuracy of the test.
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Figure CN119509322A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of material dielectric property testing, and in particular relates to a material center positioning method and system for dielectric property testing of quasi-optical cavity materials. Background Art
[0002] The statements in this section merely provide background information related to the present invention and do not necessarily constitute prior art.
[0003] The quasi-optical cavity method is the most commonly used method for testing the dielectric properties of low-loss materials in the millimeter-wave frequency band. Quasi-optical cavities are divided into two structures: hemispherical quasi-optical cavities (plano-concave cavities) and double-spherical quasi-optical cavities. The double-spherical quasi-optical cavity is more suitable for testing thin film materials.
[0004] Quasi-optical cavity test methods are divided into variable frequency method (fixed cavity length method) and variable cavity length method (fixed frequency method). In the variable frequency method, the two reflective mirrors of the cavity are fixed, and the resonant frequency change of the cavity before and after the material is placed is used for testing. The variable cavity length method adjusts the relative distance between the two reflective mirrors to keep the resonant frequency fixed before and after the material is placed, and uses the change in cavity length for testing. For thin materials, the existing frequency measurement resolution of the vector network analyzer is much higher than the physical measurement resolution of the sample thickness, and the variable frequency method has higher test accuracy.
[0005] However, the variable cavity length method has very few test frequency points, and the measurable frequency points are related to the dielectric constant of the material. In the double-spherical cavity test method using the variable frequency method, the position of the thin material has a greater impact on the measurement accuracy.
[0006] In the double-spherical cavity test method, the material to be tested needs to be placed at the center of the two mirrors, and the center of the material must coincide with the center of the fixture. The current method for locating the center of the material is to directly physically measure and find the position of half the thickness of the material as the center position. For thin film materials, due to the small thickness, the error introduced by measuring the thickness will increase significantly. When the material deviates from the center position, the error of the dielectric property test result will also increase. Therefore, it is very important to accurately locate the center of the material. Summary of the invention
[0007] In order to overcome the above-mentioned deficiencies of the prior art, the present invention provides a material center positioning method and system for dielectric property testing of quasi-optical cavity materials.
[0008] To achieve the above objectives, one or more embodiments of the present invention provide the following technical solutions:
[0009] A first aspect of the present invention provides a material center positioning method for dielectric property testing of quasi-optical cavity materials, comprising:
[0010] Obtain the placement position and corresponding resonance frequency of the material to be tested in the double-spherical quasi-optical cavity test system;
[0011] The placement position of the material to be tested is taken as the zero point, the moving distance of the material to be tested is taken as the horizontal coordinate, and the resonant frequency at the corresponding position is taken as the vertical coordinate to fit the resonant frequency change curve;
[0012] The placement position corresponding to the peak or trough of the resonant frequency variation curve is the center position of the material.
[0013] A second aspect of the present invention provides a material center positioning system for dielectric property testing of quasi-optical cavity materials, comprising:
[0014] The data acquisition module is configured to: obtain the placement position and corresponding resonance frequency of the material to be tested in the double-spherical quasi-optical cavity test system;
[0015] The resonance frequency variation curve fitting module is configured to fit the resonance frequency variation curve by taking the placement position of the material to be tested as the zero point, the moving distance of the material to be tested as the horizontal coordinate, and the resonance frequency of the corresponding position as the vertical coordinate;
[0016] The position determination module is configured to extract the placement position corresponding to the peak or trough of the resonant frequency change curve as the center position of the material.
[0017] The third aspect of the present invention provides a computer-readable storage medium having a program stored thereon, which, when executed by a processor, implements the steps in the material center positioning method for dielectric property testing of a quasi-optical cavity material as described in the first aspect of the present invention.
[0018] The fourth aspect of the present invention provides an electronic device, including a memory, a processor, and a program stored in the memory and executable on the processor, wherein when the processor executes the program, the steps in the material center positioning method for dielectric property testing of a quasi-optical cavity material as described in the first aspect of the present invention are implemented.
[0019] One or more of the above technical solutions have the following beneficial effects:
[0020] The present invention aims at the engineering problem of material center positioning in actual testing of a double-spherical quasi-optical cavity, uses the symmetrical structural characteristics of the cavity to find the central symmetry of the engineering model, and places the material at a left-right symmetrical position in the center of the double-spherical cavity; the test accuracy of the dielectric properties of the double-spherical cavity material can be improved, especially for thin film materials that are greatly affected by physical measurement errors, and the error introduced by the material center positioning offset can be eliminated.
[0021] Advantages of additional aspects of the present invention will be given in part in the following description, and in part will become obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS
[0022] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.
[0023] Figure 1 This is a flow chart of a material center positioning method for dielectric property testing of a quasi-optical cavity material in Example 1.
[0024] FIG. 2( a ) and FIG. 2( b ) are schematic diagrams of the electric field distribution inside the cavity in even mode and odd mode, respectively, of Example 1. FIG.
[0025] FIG. 3( a ) and FIG. 3( b ) are schematic diagrams showing the placement of materials to be tested in a double-spherical quasi-optical cavity testing system with different structures in Example 1. FIG.
[0026] Figure 4 This is the relationship curve between the moving distance and the resonant frequency of Example 1.
[0027] FIG. 5( a ) and FIG. 5( b ) are schematic diagrams of frequency and position curves corresponding to the even mode and the odd mode, respectively, of Example 1. FIG.
[0028] In the figure, 1, the sample to be tested, 2, the spherical mirror, 3, the coupling hole. DETAILED DESCRIPTION
[0029] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.
[0030] Embodiment 1
[0031] like Figure 1 As shown, the present invention proposes a material center positioning method for dielectric property testing of quasi-optical cavity materials, comprising:
[0032] Step 1: Obtain the placement position and corresponding resonant frequency of the material to be tested in the double-spherical quasi-optical cavity test system;
[0033] Step 2: Taking the placement position of the material to be tested as the zero point, the moving distance of the material to be tested as the abscissa, and the resonant frequency of the corresponding position as the ordinate, fit the resonant frequency change curve;
[0034] Step 3: The placement position corresponding to the peak or trough of the resonant frequency change curve is extracted as the center position of the material.
[0035] In step 1, for thin sheet materials, the current test methods in the centimeter wave band include SPDR, split resonant cavity and other methods. The measurement frequency is limited by theory, and the general test frequency does not exceed 40GHz. The test method in the millimeter wave band is the double-ball cavity test method. Most of them use the variable cavity length method for testing. There are very few test frequencies, and the measurable frequency is related to the dielectric constant of the material. In the double-ball cavity test method using the variable frequency method, the position of the thin material has a greater impact on the measurement accuracy. The present invention is a quasi-optical cavity test method based on the variable frequency method.
[0036] After placing the dielectric material, i.e., the material to be tested 1, in the double-spherical quasi-optical cavity test system, assuming that the center of the material is at the center of the fixture, the field distribution in the cavity is roughly schematically shown in Figures 2(a) and 2(b); Figure 2(a) shows that the center position is at the maximum electric field in the even mode case, and Figure 2(b) shows that the center position is at the minimum electric field in the odd mode case.
[0037] When the dielectric material is placed in the fixture, since the dielectric constant of the dielectric material is greater than that of air, when the material is at different electric field strength positions, the impact on the resonant frequency in the cavity is different. At the same time, the double-spherical cavity has a left-right symmetrical structure, but there is no corresponding symmetry at the center position. According to the electric field distribution diagram, it can be seen that the same symmetrical interference will be generated when the material moves left or right from the center position. For the even mode case, the center position is the point with the strongest electric field strength. When the material is placed at the exact center, the resonance offset in the cavity has the largest offset relative to the cavity, that is, the corresponding resonant frequency has the minimum value; when the material position is not at the center, but to the left or right, the field in the material becomes smaller relative to the center, the resonance offset will be reduced, and the corresponding test resonant frequency will be larger.
[0038] The double-spherical quasi-optical cavity test system includes: a test instrument, a test cable, a double-spherical cavity test fixture, etc. The double-spherical quasi-optical cavity fixture has two structural forms as shown in FIG3 (a) and FIG3 (b). Regardless of the structure, the material to be tested 1 is placed at the center of the two spherical mirrors 2.
[0039] As can be seen from Figure 3(a) and Figure 3(b), the material 1 to be tested has a certain thickness. When the material 1 to be tested is placed at the center of the spherical mirror 2, the distances between the left and right surfaces of the material 1 to be tested and the spherical mirror 2 should be consistent. If the placement is slightly off the center, the distances between the left and right surfaces and the spherical mirror are different. When the material thickness is thick, this deviation error has little effect on the test results; when the material is thinner, the deviation error has a greater impact on the test results. Therefore, how to determine the center position of the material 1 to be tested in the fixture is the key to accurate testing.
[0040] The material center means that the test materials are all disc-shaped materials, and the materials should share the same symmetry axis with the test fixture composed of two spherical mirrors.
[0041] In step 2, in order to solve the engineering problem of material center positioning in the actual test of the double-spherical quasi-optical cavity, the symmetrical structural characteristics of the cavity are used to find the central symmetry of the engineering model and place the material at the center.
[0042] Among them, the material position is moved by high-precision moving devices such as motors and precision slides, a curve of the relationship between the moving distance and the resonant frequency is established, the peak or trough position of the curve is found, and the physical position of the material at this time is recorded.
[0043] There is no fixed precision for the moving distance. In theory, the smaller the moving distance, the higher the precision. The smaller the moving distance, the denser the number of measurement points that can be obtained within a certain distance range, the more accurate the fitted curve, and the more accurate the peak or trough found. The relationship curve between the moving distance and the resonant frequency is as follows: Figure 4 As shown, the ordinate is the resonant frequency (unit: GHz), and the abscissa is the distance moved left and right after a reference position is selected (unit: mm). Figure 4 In the figure, 7 points are scanned and the moving distance is 0.5 mm. If the moving distance is 0.1 mm or less, more discrete scanning points can be obtained and the fitting curve is closer to the trigonometric function curve.
[0044] In step 3, the double-spherical cavity test method can test fewer frequency points on the one hand, because the material thickness needs to meet the test frequency half wavelength integer multiples to test. That is to say, a material of a specific thickness basically corresponds to one or two test frequency points. On the other hand, the test error for thin materials is relatively large. The present invention can improve the test accuracy of the dielectric properties of double-spherical cavity materials, especially for thin film materials such as thin films where the physical measurement error has a large impact. By finding the exact position where the hardware system matches the theoretical model, the signal scanning under the loaded material is completed, and the error introduced by the material center positioning offset is eliminated.
[0045] Assuming the center position is 0, the corresponding change curve of the position and the resonant frequency is shown in Figure 5(a), where the lowest point of the curve is the center position of the material. Similarly, in the odd-mode case, the center position has the weakest electric field, that is, the placement position corresponding to the trough of the resonant frequency change curve; the electric field at the material moves left and right, and the resonance offset becomes larger;
[0046] In the even mode case, the center position has the strongest electric field, which is the placement position corresponding to the peak of the resonant frequency change curve; the electric field at the material moves left and right, and the resonance offset becomes smaller; the corresponding curve change is shown in Figure 5(b), and the highest point of the curve is the center position of the material.
[0047] It should be noted that odd mode and even mode are two adjacent modes in the double-sphere quasi-optical cavity solution theory. Solving the differential equation in the cylindrical coordinate system can obtain two solutions, sine and cosine. In the double-sphere cavity, as the test frequency increases, the odd mode solution and the even mode solution appear alternately.
[0048] Embodiment 2
[0049] This embodiment discloses a material center positioning system for dielectric property testing of quasi-optical cavity materials, including:
[0050] The data acquisition module is configured to: obtain the placement position and corresponding resonance frequency of the material to be tested in the double-spherical quasi-optical cavity test system;
[0051] Wherein, the material to be tested is a thin film material, and the thickness of the material to be tested is an integer multiple of half the wavelength of the test frequency.
[0052] The resonance frequency variation curve fitting module is configured to fit the resonance frequency variation curve by taking the placement position of the material to be tested as the zero point, the moving distance of the material to be tested as the horizontal coordinate, and the resonance frequency of the corresponding position as the vertical coordinate;
[0053] The position determination module is configured to extract the placement position corresponding to the peak or trough of the resonant frequency change curve as the center position of the material.
[0054] Embodiment 3
[0055] The purpose of this embodiment is to provide a computer-readable storage medium.
[0056] A computer-readable storage medium stores a computer program thereon, which, when executed by a processor, implements the steps in a material center positioning method for dielectric property testing of a quasi-optical cavity material as described in Example 1 of the present disclosure.
[0057] Embodiment 4
[0058] The purpose of this embodiment is to provide an electronic device.
[0059] An electronic device includes a memory, a processor, and a program stored in the memory and executable on the processor. When the processor executes the program, the steps in the material center positioning method for dielectric property testing of a quasi-optical cavity material as described in Example 1 of the present disclosure are implemented.
[0060] The steps involved in the apparatuses of the above embodiments 2, 3 and 4 correspond to the method embodiment 1, and the specific implementation methods can refer to the relevant description part of embodiment 1. The term "computer-readable storage medium" should be understood as a single medium or multiple media including one or more instruction sets; it should also be understood to include any medium that can store, encode or carry an instruction set for execution by a processor and enable the processor to execute any method in the present invention.
[0061] Those skilled in the art should understand that the modules or steps of the present invention described above can be implemented by a general-purpose computer device, or alternatively, they can be implemented by a program code executable by a computing device, so that they can be stored in a storage device and executed by the computing device, or they can be made into individual integrated circuit modules, or multiple modules or steps therein can be made into a single integrated circuit module for implementation. The present invention is not limited to any specific combination of hardware and software.
[0062] Although the above describes the specific implementation mode of the present invention in conjunction with the accompanying drawings, it is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art on the basis of the technical solution of the present invention without creative work are still within the scope of protection of the present invention.
Claims
1. A material center positioning method for dielectric property testing of quasi-optical cavity materials, characterized in that: include: Obtain the placement position and corresponding resonance frequency of the material to be tested in the double-spherical quasi-optical cavity test system; The placement position of the material to be tested is taken as the zero point, the moving distance of the material to be tested is taken as the horizontal coordinate, and the resonant frequency at the corresponding position is taken as the vertical coordinate to fit the resonant frequency change curve; The placement position corresponding to the peak or trough of the resonant frequency variation curve is the center position of the material.
2. The material center positioning method for dielectric property testing of quasi-optical cavity materials according to claim 1, characterized in that: The material to be tested is a thin film material, and the thickness of the material to be tested is an integer multiple of a half wavelength of a test frequency.
3. The material center positioning method for dielectric property testing of quasi-optical cavity materials according to claim 1, characterized in that: When the material to be tested is placed at the center, the material to be tested and the test fixture composed of two spherical mirrors share a common symmetry axis.
4. The material center positioning method for dielectric property testing of quasi-optical cavity materials according to claim 1, characterized in that: The moving components are used to drive the material to be tested to move left and right, and the moving distances of multiple groups of materials to be tested and the resonant frequencies at corresponding positions are obtained.
5. The material center positioning method for dielectric property testing of quasi-optical cavity materials according to claim 4, characterized in that: The moving component is an electric slide.
6. The material center positioning method for dielectric property testing of quasi-optical cavity materials according to claim 1, characterized in that: Odd mode and even mode are two adjacent modes in the double-sphere quasi-optical cavity solution theory. In odd mode, the center position of the material is the placement position corresponding to the trough of the resonance frequency change curve; in even mode, the center position of the material is the placement position corresponding to the peak of the resonance frequency change curve.
7. A material center positioning system for dielectric property testing of quasi-optical cavity materials, characterized in that: include: The data acquisition module is configured to: obtain the placement position and corresponding resonance frequency of the material to be tested in the double-spherical quasi-optical cavity test system; The resonance frequency variation curve fitting module is configured to fit the resonance frequency variation curve by taking the placement position of the material to be tested as the zero point, the moving distance of the material to be tested as the horizontal coordinate, and the resonance frequency of the corresponding position as the vertical coordinate; The position determination module is configured to extract the placement position corresponding to the peak or trough of the resonant frequency change curve as the center position of the material.
8. The material center positioning system for dielectric property testing of quasi-optical cavity materials according to claim 7, characterized in that: The material to be tested is a thin film material, and the thickness of the material to be tested is an integer multiple of a half wavelength of a test frequency.
9. A computer-readable storage medium having a program stored thereon, characterized in that: When the program is executed by a processor, the steps in the material center positioning method for dielectric property testing of quasi-optical cavity materials as described in any one of claims 1 to 7 are implemented.
10. An electronic device comprising a memory, a processor, and a program stored in the memory and executable on the processor, characterized in that: When the processor executes the program, the steps in the material center positioning method for dielectric property testing of quasi-optical cavity materials as described in any one of claims 1 to 7 are implemented.