Testing method and testing system for dielectric stability of plate-shaped material

Abstract

The invention discloses a plate-shaped material dielectric stability test method and test system, and relates to the technical field of electromagnetic measurement. The method for testing the dielectric stability of the plate-shaped material comprises the following steps that 1, a planar capacitance resonance module is attached to the upper surface of a to-be-tested material, and the planar capacitance resonance module comprises a resonance coil and two capacitance plates arranged on the same plane, two terminals of the resonance coil are respectively connected with the two capacitor plates in a one-to-one correspondence manner; 2, the frequency analyzer reads resonant frequency information through a coupler matched with the planar capacitance resonance module; 3, the temperature of the material to be measured is measured, the temperature and the characteristic points of the resonant frequency information are compared with a pre-stored parameter comparison table, a corresponding dielectric constant is obtained and serves as an actually-measured dielectric constant, and the parameter comparison table records the corresponding relation of the temperature, the characteristic points of the resonant frequency information and the dielectric constant; and 4, comparing the actually measured dielectric constant with the theoretical dielectric constant. According to the invention, nondestructive testing can be realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electromagnetic measurement, in particular to the test of material dielectric constant stability. BACKGROUND

[0002] With the rapid development of electronic technology, test systems and equipment are evolving towards miniaturization, portability and high efficiency. At the same time, the application of plate-shaped materials in modern communication, aerospace and other high-tech fields is becoming increasingly widespread, and the demand for accurate characterization of their key performance parameters continues to increase. However, the current mainstream method for testing the dielectric constant stability of plate-shaped materials generally relies on vector network analyzers or impedance analyzers for testing fixed-size material samples. Such devices not only have a large volume and high cost, but also have high requirements for the use environment, and are difficult to adapt to on-site detection and rapid testing scenarios.

[0003] Currently, plate-shaped electromagnetic functional materials are mainly used in antenna covers, electromagnetic functional skins and other key projects. As the requirements for material dielectric stability indicators continue to increase, the development of rapid, high-resolution detection methods has become a key issue that needs to be addressed in this testing field. Resonance refers to the connection of inductance and capacitance in series or parallel, so that the inductive reactance of inductance and the capacitive reactance of capacitance cancel each other out at a specific frequency, making the overall circuit exhibit pure resistance characteristics. Based on this basic characteristic of resonance, the resonant frequency can be accurately obtained under a specific circuit structure, which provides an effective way for high-precision characterization of material dielectric properties.

[0004] Chinese patent application 202011383414.9 discloses a relative dielectric constant testing technology, which adopts a resonance method, bonds the ground plane (i.e. the second ground layer) of the microstrip line to the lower surface of the substrate to be tested, sets a resonance guide strip on the upper surface of the substrate, connects the probe to the measuring device through the electrical connection part, and measures the resonant frequency of the transmission line by placing the probe close to the resonance guide strip on the upper surface of the substrate. Based on the pre-set variation relationship between the relative dielectric constant of the medium to be tested and the resonant frequency and the thickness of the substrate, the relative dielectric constant of the medium to be tested is obtained. By setting the second ground layer and the resonance guide strip on the medium to be tested, and connecting the second ground layer to the medium to be tested by bonding, the relative dielectric constant of the medium to be tested can be tested without damaging the medium to be tested. The technology of Chinese patent application 202011383414.9 needs to set microstrip lines on the upper and lower surfaces of the medium to be tested, which cannot realize non-destructive testing for already installed equipment.

[0005] Chinese patent application 202211046593.6 provides a millimeter wave dielectric property testing device and method for electrically oriented liquid crystal material, which designs a liquid crystal cell composed of multiple layers of media, uses a multi-layer media to form an upper and lower symmetric TM 0n0The double-sided circular patch resonator has an internal electric field distribution that passes through the multilayer dielectric under test and is perpendicular to the metal disc. Therefore, by utilizing its internal field distribution characteristics, this structure can use modes with higher resonant frequencies.

[0006] Chinese patent application 202110984878.3 provides a dual-band lossless dielectric constant measurement sensor technology based on a spiral resonator. According to paragraph 0031 of its specification, from bottom to top, it includes a ground layer (3), a dielectric layer (2), and a metal patch layer (1).

[0007] Chinese patent applications 202211046593.6 and 202110984878.3 both pertain to resonant cavity Q-value testing. These require a coupled excitation source and a detection source, necessitate dual-port testing, and both require destroying the sample and placing it in a fixed position, making on-site testing during construction and maintenance impossible. Furthermore, resonant cavity Q-value testing places significant demands on material loss; excessive loss will cause the cavity Q-value to exceed its transformation range. Summary of the Invention

[0008] The technical problem to be solved by the present invention is to provide a method and system for testing the dielectric stability of plate-shaped materials, which can conveniently realize high-precision non-destructive field testing.

[0009] The technical solution adopted by the present invention to solve the aforementioned technical problem is a method for testing the dielectric stability of plate-shaped materials, comprising the following steps: Step 1: Attach a planar capacitor resonant module to the upper surface of the material to be tested. The planar capacitor resonant module includes a resonant coil and two capacitor plates disposed on the same plane. The two terminals of the resonant coil are respectively connected to the two capacitor plates one by one. Step 2: The frequency analyzer reads the resonant frequency information through a coupler adapted to the planar capacitor resonant module; Step 3: Measure the temperature of the material to be tested, compare the characteristic points of temperature and resonant frequency information with the pre-stored parameter lookup table, and obtain the corresponding dielectric constant as the measured dielectric constant. The parameter lookup table records the correspondence between the characteristic points of temperature and resonant frequency information and the dielectric constant. Step 4: Compare the measured dielectric constant with the theoretical dielectric constant.

[0010] Furthermore, the planar capacitor resonant module includes an electrode spacing adjustment structure, which has at least two selectable positions, each position corresponding to a preset electrode spacing; Furthermore, the frequency analyzer is a vector network analyzer, impedance analyzer, or inductance-capacitance meter (LCR meter).

[0011] The characteristic point of the resonant frequency information is the frequency point where the resonant peak is located.

[0012] The application also provides a plate material dielectric stability test system adopting the plate material dielectric stability test method, and the plate material dielectric stability test system comprises the following parts: The planar capacitive resonance module comprises two capacitive plates arranged on the lower surface of the substrate and a resonance coil arranged on the upper surface of the substrate. The frequency analyzer is connected with the two connection ends of the coupler through the signal input end and connected with the detection query module through the output end. The detection query module stores the corresponding relationship among the temperature, the characteristic point of the resonance frequency information and the dielectric constant. The temperature sensor is arranged on the lower surface of the substrate, and the output end of the temperature sensor is connected with the detection query module, so as to detect the temperature of the material to be tested.

[0013] Further, the planar capacitive resonance module comprises a capacitive plate spacing adjustment structure having at least two optional gears, each gear corresponding to a preset plate spacing; and the detection query module stores the corresponding relationship among the temperature, the characteristic point of the resonance frequency information, the plate spacing and the dielectric constant.

[0014] The application has the advantages that the dielectric constant of the material to be tested can be measured conveniently and accurately, the installation state of the material is not affected, the nondestructive detection of "contacting for testing" can be realized, and the application is completely suitable for the working conditions of the construction site and the maintenance detection after installation. The application has the characteristics of low cost and high precision.

[0015] The application provides a plate material dielectric constant stability test system and a test method thereof, which innovatively adopts a pasting test method, combines a capacitive parallel resonance principle, effectively widens a capacitive dynamic adjustment range, and significantly improves the measurement resolution and sensitivity of the dielectric stability of the plate material. In the test process, the parallel resonance circuit enters a resonance state at a specific frequency, at which time the circuit current is minimum, the voltage is highest, and the equivalent impedance reaches a peak value. The plate material to be tested is directly pasted on the surface of the parallel resonance circuit, the loss of the dielectric changes the electric field distribution of the resonance region, which equivalently adjusts the capacitance in the circuit, thereby causing a significant shift of the resonance frequency. The change of the resonance frequency is collected through a high-precision test instrument, and a data processing algorithm is combined to accurately evaluate the stability of the dielectric constant of the plate material. BRIEF DESCRIPTION OF DRAWINGS

[0016] In order to more clearly illustrate the technical solutions of the embodiments of the application, the following will briefly introduce the drawings needed to be used in the embodiments. It should be understood that the following drawings only show some embodiments of the application, and therefore should not be regarded as a limitation on the scope. Other related drawings can also be obtained by those skilled in the art without creative labor.

[0017] Figure 1 is a schematic diagram of the principle of the present application; Figure 2 is a schematic diagram of the characteristic point of the resonance frequency information; Figure 3 is a schematic diagram of the upper surface structure of the substrate of the planar capacitive resonance module structure of the present application; Figure 4 is a schematic diagram of the lower surface structure of the substrate of the planar capacitive resonance module structure of the present application; Figure 5 is a schematic diagram of the lower surface structure of the substrate of Example 2. DETAILED DESCRIPTION

[0018] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are some but not all of the embodiments of the present application. The components of the embodiments of the present application described and shown in the drawings herein can be arranged and designed in various different configurations.

[0019] The present application provides a kind of based on sticking parallel resonance structure Board-shaped material dielectric constant test scheme.System uses portable test instrument as signal source and detection unit, directly stick to the resonance circuit of the material to be measured, constitute adjustable resonance system.Due to the difference of different materials and loss characteristics, it will change the equivalent capacitance of resonance region, and then cause the significant deviation of parallel resonance frequency.Through the position change of accurately capturing resonance frequency, the transformation of impedance information, in combination with calibration database, the difference and stability of material dielectric constant can be quickly distinguished and evaluated.The method is simple and fast in operation, suitable for on-site, efficient detection and screening of multiple batches of material performance.

[0020] Unlike prior art, which needs to set test components on the upper and lower sides of the medium, the present application only needs to set test components on one side surface of the material to be measured to complete accurate testing without damaging the installation of the material to be measured, truly realizing on-site nondestructive testing.

[0021] Example 1

[0022] Reference is made to Figure 1 and Figure 2 .

[0023] Figure 2 The resonance frequency curves of two materials (material A and material B) with different dielectric constants are shown, and the vertical coordinate S 11The reflectivity and the visible dielectric constant of the materials are different, and the frequency points corresponding to the resonance peaks are different. If a sample with a designed dielectric constant of 15 is tested, the resonance peak frequency obtained by testing is 0.28 GHz. In the database, the frequency 0.28 GHz obtained by testing is queried, and if the frequency (X-axis corresponding to the peak value) of the resonance peak of the material with a dielectric constant of 15 is 0.28 GHz, it is considered that the dielectric constant of the material is 15, which proves that the dielectric constant of the material is consistent with the designed value, that is, the stability is confirmed.

[0024] The plate-shaped material dielectric stability test method provided in the embodiment includes the following steps: Step 1: affix a planar capacitive resonance module to the upper surface of the material to be tested, the planar capacitive resonance module including two capacitive plates arranged on the same plane and a resonance coil, two terminals of the resonance coil being connected to the two capacitive plates one by one in a one-to-one correspondence; Step 2: a frequency analyzer reads resonance frequency information through a coupler adapted to the planar capacitive resonance module; Step 3: comparing characteristic points of the resonance frequency information with a pre-stored parameter comparison table to obtain a corresponding dielectric constant as a measured dielectric constant; Step 4: comparing the measured dielectric constant with a theoretical dielectric constant.

[0025] The test system of the application includes: The planar capacitive resonance module includes two capacitive plates arranged on the lower surface of the substrate and a resonance coil arranged on the upper surface of the substrate; Figure 3 The resonance coil on the upper surface of the substrate is shown, Figure 4 The capacitive plate distribution diagram on the lower surface of the substrate is shown, and the shaded area represents the capacitive plate. The resonance coil and the capacitive plate are connected by a through hole penetrating the substrate.

[0026] The frequency analyzer is connected to the two connection ends of the coupler through the signal input end, and is connected to the detection query module through the output end. The frequency analyzer refers to a device capable of analyzing the resonance frequency, such as a single-port vector network analyzer with a model number of Copper Mountain-R60, or an impedance analyzer, an LCR meter, etc., which are mature devices; The temperature sensor has a temperature detection point arranged on the lower surface of the substrate and in the same plane as the capacitive plate. The output end of the temperature sensor is connected to the detection query module for detecting the temperature of the material to be tested. The detection query module stores the corresponding relationship between the characteristic points of the resonance frequency information and the dielectric constant. The characteristic points of the resonance frequency information are the frequency points of the resonance peaks, which are referred to as resonance frequency points in the application.

[0027] The detection query module receives frequency information from the frequency analyzer and temperature information from the temperature sensor, calculates the characteristic point of the resonance frequency information from the frequency information, then queries and compares in the parameter comparison table recording the temperature, the characteristic point of the resonance frequency information, and the dielectric constant corresponding information, and outputs the stability judgment result.

[0028] Working process: First, the detection query module (PC or other forms of computers, such as tablets) saves the parameter comparison table in the form of a database, such as Table 1: Table 1 dielectric constant temperature resonance frequency point 14 -40℃ 267.4 MHz 14 -20℃ 268.7 MHz 14 0℃ 270.6 MHz 14 20℃ 271.3 MHz 14 40℃ 272.0 MHz 22 -40℃ 226.7 MHz 22 -20℃ 228.2 MHz 22 0℃ 230.0 MHz 22 20℃ 231.1 MHz 22 40℃ 231.8 MHz The above table only shows the corresponding relationship in the form of a table, and the actual data saving form is not limited to the table mode.

[0029] The characteristic point of the resonance frequency information is the frequency point where the resonance peak is located (the same for the wave crest and wave trough), and the dielectric constant is the dielectric constant.

[0030] During detection, the planar capacitor resonance module is attached to the surface of the material to be tested, and the portable frequency analyzer collects the resonance parameters of the planar capacitor resonance module through the coupler, which appears as the frequency point where the resonance peak is located on the frequency analyzer; combined with the material temperature data collected by the temperature sensor, the dielectric constant corresponding to the temperature and frequency point data is retrieved in the detection query module, that is, the measured dielectric constant is obtained, which is compared with the design parameters (i.e. theoretical parameters) of the material to be tested, so that the dielectric constant stability of the measured material can be judged.

[0031] Specific description: The frequency analyzer can be a commercially available portable vector network analyzer, impedance analyzer, or LCR meter that can record transmission line port characteristics, and has a single-port test function that can dynamically analyze the S parameters or impedance parameters of the port.

[0032] A general standard mechanical calibration piece is used, which is an open circuit calibration piece, a short circuit calibration piece, and a 50 ohm load calibration piece, to calibrate the terminal test port of the instrument.

[0033] The coupler connects the frequency analyzer with a radio frequency transmission line, which can radiate and accept electromagnetic wave signals to the resonance circuit. The coupler structure is a small loop antenna with no obvious resonance characteristics in the test frequency band.

[0034] The resonator and the planar capacitor are used to form a parallel resonance circuit, which can be used for testing the material to be tested. The resonator is mainly composed of a high-frequency Q inductor and a structural capacitor.

[0035] The planar capacitor is composed of two coplanar parallel metal electrodes. During testing, the coplanar parallel metal electrodes are attached to the surface of the plate-shaped material to be tested.

[0036] The plate-shaped material is a composite material composed of various resins and functional materials, and the dielectric constant of the plate-shaped material suitable for the application can reach 1-200, which is superior to the prior art.

[0037] The test process is divided into three parts: system calibration, sample application and parameter comparison.

[0038] Calibration: Adjust the test instrument to the frequency band to be tested, connect one end of the cable to the test instrument port, and connect the other end to the calibration piece respectively to calibrate the port.

[0039] Test: Apply the planar capacitor to the surface of the standard sample material, and place the coupler connected to the test instrument above it to test the sample and record the sample resonance frequency position, resonance point impedance and reflectivity information.

[0040] The standard sample material is a material sample with known material parameters, including material shape size, material thickness, material stacking structure, material dielectric constant and material magnetic permeability.

[0041] Apply the planar capacitor and temperature sensor to the surface of the plate-shaped material to be tested, and place the coupler connected to the test instrument above it to test the sample and record the sample temperature, resonance frequency position, resonance point impedance and reflectivity information.

[0042] Combine the test data of the sample to be tested and the standard sample data, compare the test temperature, resonance frequency position, resonance point impedance and reflectivity information with the calibration data, record the data deviation, and evaluate the stability of the dielectric constant of the plate-shaped material according to the maximum allowable deviation of each data.

[0043] The application can accurately detect the dielectric constant stability of the material under different temperature environments, and has high practical value in the field of new material testing.

[0044] Example 2: see Figure 5 .

[0045] On the basis of example 1, the application adds the function of adjustable capacitor to further eliminate the limitations of single test parameter.

[0046] The planar capacitor resonance module of the embodiment includes a capacitor plate spacing adjustment structure 40, which has at least two selectable gears (which can be set by a scale), and each gear corresponds to a preset plate spacing. Ordinary technicians can implement according to the content of the specification, and the specific structure is not described here.

[0047] The detection query module stores the correspondence between the characteristic points recording temperature and resonance frequency information, the plate spacing and the dielectric constant.

[0048] By using the embodiment, the detection results under different plate spacings can be compared and verified to improve the measurement accuracy.

[0049] Embodiment 3

[0050] As an alternative to embodiment 2, the test system of the embodiment is configured with a plurality of planar capacitive resonance modules, each of which has different capacitance parameters or inductance parameters. By using the embodiment, the test under different resonance parameters is realized in the form of replacing the planar capacitive resonance modules.

Claims

1. A method for testing the dielectric stability of a sheet material, characterized in that, The method comprises the following steps: Step 1: attaching a planar capacitive resonance module on the upper surface of the material to be measured, the planar capacitive resonance module comprising a resonance coil and two capacitive plates arranged on the same plane, and the two terminals of the resonance coil being connected to the two capacitive plates one by one in correspondence; Step 2: reading the resonance frequency information by a frequency analyzer through a coupler matched with the planar capacitive resonance module; Step 3: measuring the temperature of the material to be measured, comparing the temperature and the characteristic point of the resonance frequency information with a pre-stored parameter comparison table to obtain the corresponding dielectric constant as the measured dielectric constant, the parameter comparison table recording the corresponding relationship among the temperature, the characteristic point of the resonance frequency information and the dielectric constant; Step 4: comparing the measured dielectric constant with the theoretical dielectric constant.

2. The method of dielectric stability testing of sheet materials of claim 1, wherein, The planar capacitive resonance module comprises a plate spacing adjustment structure having at least two selectable gears, each gear corresponding to a preset plate spacing.

3. The method of testing the dielectric stability of a sheet material of claim 1 wherein, The frequency analyzer is a vector network analyzer, an impedance analyzer or an inductance capacitance tester.

4. The method of testing the dielectric stability of a sheet material of claim 1 wherein, The characteristic point of the resonance frequency information is the frequency point at which the resonance peak is located.

5. A system for testing the dielectric stability of a sheet material, characterized by The method for testing the dielectric stability of the plate-shaped material comprises the following steps: a planar capacitive resonance module comprising two capacitive plates arranged on the lower surface of a substrate and a resonance coil arranged on the upper surface of the substrate; a frequency analyzer, the signal input end of which is connected to the two connection ends of the coupler, and the output end of which is connected to a detection query module; a detection query module, which stores the corresponding relationship among the temperature, the characteristic point of the resonance frequency information and the dielectric constant; a temperature sensor, the temperature detection point of which is arranged on the lower surface of the substrate, and the output end of which is connected to the detection query module, for detecting the temperature of the material to be measured; the detection query module stores the corresponding relationship among the temperature, the characteristic point of the resonance frequency information and the dielectric constant.

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