A system and method for testing dielectric properties of a wave-transparent material under high temperature and high pressure

Abstract

The application aims to provide a dielectric property testing system and method of a wave-transparent material under high temperature and high pressure, and belongs to the technical field of microwave and millimeter wave dielectric material testing. The system innovatively adds a temperature device for heating and a pressure device for pressurizing in a conventional quasi-optical cavity method testing device, and sets a fused quartz considering the influence of temperature and pressure on the optical cavity, so that the system can test the dielectric property of the wave-transparent material under high temperature and high pressure by using the quasi-optical cavity method. Meanwhile, the system is simple to operate and has high testing precision.

Description

Technical Field

[0001] This invention belongs to the field of microwave and millimeter-wave testing technology, specifically relating to a system and method for testing the dielectric properties of wave-transparent materials under high temperature and high pressure. Background Technology

[0002] Millimeter-wave materials are crucial foundational materials in numerous fields, including national defense, military equipment, aerospace, and electronic communications. With the development of technologies such as communication, telemetry, guidance, detonation, navigation, electronic countermeasures, and stealth, increasingly stringent requirements are being placed on the stability, consistency, and application under high-temperature and high-pressure environments of millimeter-wave materials. For example, when aircraft, missiles, rockets, and other aerospace equipment fly at high speeds, the friction between the high-speed airflow and the equipment's nose cone increases dramatically, causing a sharp rise in the temperature and pressure of the nose cone material. The dielectric parameters of microwave materials exhibit nonlinear changes under high-temperature and high-pressure environments, which significantly impacts the transmission and reception of signals by the aircraft's antenna. Therefore, accurately testing and analyzing the changes in the dielectric parameters of these microwave materials under high-temperature and high-pressure environments is of paramount practical importance.

[0003] Quasi-optical cavities possess extremely high Q values ​​and simple operating modes, with higher-order modes having minimal impact on the master mode. The open cavity facilitates sample placement and operation, making them highly suitable for measuring the dielectric properties of wave-transparent materials. Currently, research on measuring the dielectric properties of wave-transparent materials using the quasi-optical cavity method mainly focuses on ambient or low-temperature environments. Dong Angran's paper, "Research on Low-Temperature Testing Technology of Material Dielectric Parameters Using Quasi-Optical Cavity Method," constructed a quasi-optical cavity variable-temperature testing system operating at -50℃ to 100℃, studying the effects of temperature and frost on the quasi-optical cavity performance, and combining semiconductor decooling and dehumidification with the quasi-optical cavity. However, this study only addresses the measurement of the complex dielectric constant of materials under low-temperature and ambient-temperature environments (-50℃ to 100℃), and the system is not suitable for testing the dielectric constant under high-temperature and high-pressure environments. Furthermore, this method only addresses the measurement of the complex dielectric constant under temperature fields and does not involve pressure fields.

[0004] In summary, current domestic and international research on quasi-optical cavity technology for extracting and detecting the dielectric constant of microwave-transparent materials mainly focuses on testing under isolated low-temperature and ambient-temperature environments. Furthermore, it only studies methods for extracting the dielectric constant under temperature fields while neglecting the effect of pressure fields. Therefore, developing a technology for extracting the dielectric constant of microwave-transparent materials using quasi-optical cavities under high temperature and high pressure conditions is of significant practical importance for current microwave material testing. Summary of the Invention

[0005] To address the problems existing in the background technology, the purpose of this invention is to provide a system and method for testing the dielectric properties of wave-transparent materials under high temperature and high pressure. This system innovatively adds a temperature device for heating and a pressure device for pressurizing to a conventional quasi-optical cavity method testing apparatus, and incorporates fused silica to account for the influence of temperature and pressure on the optical cavity. This enables the system to test the dielectric properties of wave-transparent materials using the quasi-optical cavity method under high temperature and high pressure. Furthermore, the system is easy to operate and offers high testing accuracy.

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

[0007] A dielectric property testing system for wave-transparent materials under high temperature and high pressure includes a temperature display 1, a pressure display 2, a pressurizer 3, a pressure sensor 4, a heat-insulating metal layer 5, a plane mirror 6, a water-cooling unit 7, a heating induction coil 8, fused silica 10, a quasi-optical cavity spherical mirror 11, a first quasi-optical cavity coaxial coupling ring 12, a second quasi-optical cavity coupling ring 13, a vector network analyzer 14, a temperature controller 15, and a temperature sensor 16.

[0008] The planar mirror 6, the heat-insulating metal layer 5, the pressure sensor 4, and the pressurizer 3 are fixedly connected from top to bottom. The microwave material 9 to be tested is placed on the surface of the planar mirror 6 with the centers of both located on the same vertical line. Fused silica is disposed on the surface of the microwave material 9, with the bottom surface of the fused silica being flat and the top surface being curved. The dimensions of the top surface are completely consistent with those of the quasi-cavity spherical mirror 11. The quasi-cavity spherical mirror 11 is positioned directly above the microwave material 9 to be tested, and the normal at the center of the microwave material 9 to be tested passes through the center of the quasi-cavity spherical mirror. The radius of the microwave material 9 to be tested should be greater than the waist radius of the Gaussian beam at the same height. The first quasi-cavity coaxial coupling ring 12 and the second quasi-cavity coaxial coupling ring 13 are symmetrically arranged on the quasi-cavity spherical mirror 11, and the first quasi-cavity coaxial coupling ring 12 and the second quasi-cavity coaxial coupling ring 13 are respectively connected to the two ends of the vector network analyzer 14.

[0009] A plane mirror 6 and a heating induction coil 8 are installed on the microwave material to be tested. The heating induction coil 8 is connected to a temperature controller 15, which heats the microwave material to be tested through induction heating. A water-cooling tank is installed inside the heat-insulating metal layer 5 and is connected to a water-cooling unit 7 to reduce the temperature. A temperature sensor 16 is installed on the microwave material to be tested 9 and is connected to a temperature display 1 to measure and read the temperature of the microwave material to be tested 9 in real time. A pressure display 2 is connected to a pressure sensor 4 to read the magnitude of the force applied to the microwave material to be tested 9 in real time. A pressure pressurizer 3 is used to pressurize the microwave material to be tested 9.

[0010] Furthermore, the microwave material 9 to be tested should be manufactured according to standard dimensions, specifically 200mm × 200mm × 2mm in length, width, and height. At the same time, the surface of the microwave material to be tested should be smooth and flat to allow the Gaussian beam to propagate as an approximately plane wave in a direction perpendicular to the surface of the microwave material to be tested.

[0011] Furthermore, the heat-insulating metal layer 5 is made of high-temperature metal, and should ensure that the microwave material under test does not oxidize when heated to above 1000°C.

[0012] Furthermore, the pressure device 3 includes a metal support frame and a pressure screw. The metal support frame is used to fix and support the pressure sensor 4, and the pressure screw is used to apply pressure to the pressure sensor 14 by screwing it in.

[0013] Furthermore, the surface of the quasi-cavity spherical mirror 11 is silver-plated to improve the reflective performance of the reflecting surface.

[0014] Furthermore, the distance between the center of the quasi-cavity spherical mirror and the plane mirror is D, and the value of D remains constant.

[0015] This invention also provides a method for dielectric testing of wave-transparent materials based on the above-described testing system, comprising the following steps:

[0016] Step 1. Place the first fused silica, and adjust the distance D between the center of the collimated cavity spherical mirror and the plane mirror to make the vector network analyzer show a resonance peak;

[0017] Step 2. Fix the position of the quasi-optical cavity spherical mirror in Step 1, and test without placing the microwave material to be tested. Heat and pressurize the quasi-optical cavity to the target value. After the temperature and pressure stabilize, use a vector network analyzer to record the resonant frequency f0 when no sample is placed.

[0018] Step 3. Place the microwave material to be tested above the plane mirror, then place the second fused silica, keeping the distance D between the center of the quasi-cavity spherical mirror and the plane mirror constant. Heat the sample and plane mirror to the target value, and after the temperature and pressure stabilize, use a vector network analyzer to test the resonant frequency f of the material under the required microwave electric field strength. L ;

[0019] Step 4. Based on the resonant frequency f when the material under test is loaded, as measured in Step 3. L Based on the resonant frequency f0 measured in step 2, the dielectric constant ε of the material under test is calculated. r The calculation process is as follows:

[0020]

[0021]

[0022]

[0023]

[0024] Where R0 is the radius of curvature of the quasi-optical cavity, t is the thickness of the material under test, n1 is the refractive index of the sample under test, n2 is the refractive index of fused silica, ω0 is the beam waist radius of the quasi-optical cavity, D is the cavity length of the quasi-optical cavity, c is the electromagnetic wave propagation speed, q is the longitudinal mode number of the resonant electromagnetic field in the quasi-optical cavity, k is the wavenumber when the sample under test is loaded into the quasi-optical cavity, d, d′, and s0 are all intermediate variables, and φ D φ T For intermediate process quantities;

[0025] The dielectric constant ε of the wave-transparent material under specific temperature and pressure can then be obtained. r .

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

[0027] This invention innovatively designs a novel quasi-optical cavity method testing system and simultaneously develops an electromagnetic parameter extraction algorithm, enabling the extraction of the dielectric constant of transparent materials under the combined effects of high temperature and high pressure under microwave irradiation. The system of this invention has advantages such as wide testing bandwidth, simple detection method, and high testing accuracy. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the dielectric performance testing system under high temperature and high pressure according to the present invention;

[0029] Among them, 1 is a temperature display instrument, 2 is a pressure display instrument, 3 is a pressurizer, 4 is a pressure sensor, 5 is a heat-insulating metal layer, 6 is a plane mirror, 7 is a water-cooled box, 8 is a heating induction coil, 9 is the wave-transmitting material to be tested, 10 is fused silica, 11 is a quasi-optical cavity spherical mirror, 12 is the first quasi-optical cavity coaxial coupling ring, 13 is the second quasi-optical cavity coupling ring, 14 is a vector network analyzer, 15 is a temperature controller, and 16 is a temperature sensor. Detailed Implementation

[0030] 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.

[0031] Example 1

[0032] A system for testing the dielectric properties of wave-transparent materials under high temperature and high pressure, the overall structure of which is as follows: Figure 1As shown, it includes a temperature display 1, a pressure display 2, a pressurizer 3, a pressure sensor 4, a heat-insulating metal layer 5, a plane mirror 6, a water-cooled box 7, a heating induction coil 8, fused silica 10, a quasi-optical cavity spherical mirror 11, a first quasi-optical cavity coaxial coupling ring 12, a second quasi-optical cavity coupling ring 13, a vector network analyzer 14, a temperature controller 15, and a temperature sensor 16;

[0033] The plane mirror 6, the heat-insulating metal layer 5, the pressure sensor 4, and the pressurizer 3 are fixedly connected from top to bottom and located vertically below the center of the microwave material 9 to be tested. The microwave material 9 to be tested is a cuboid with dimensions of 200mm × 200mm × 2mm. The surface of the microwave material to be tested should be smooth and flat to allow the Gaussian beam on the surface of the plane mirror 6 to propagate in an approximately plane wave form in a direction perpendicular to the surface of the microwave material to be tested. Fused silica is disposed on the surface of the microwave material 9, with a flat bottom and an arc top, the top surface dimensions being identical to the quasi-optical cavity spherical mirror 11. A heating induction coil 8 is disposed on the plane mirror 6 and the microwave material to be tested. The heating induction coil 8 is connected to a temperature controller 15, which outputs a low-pressure, high-pressure output. The current is used to heat the microwave material under test through induction heating, thereby controlling the temperature of the microwave material under test; a water-cooling tank is set inside the heat-insulating metal layer 5, and a water-cooling box 7 is connected to the outside through water pipes to reduce the temperature and prevent high temperature from damaging the pressure sensor 4; the temperature sensor 16 is set on the microwave material under test and is connected to the temperature display instrument 1 through wires for real-time measurement and reading of the temperature of the microwave material under test; the pressure sensor 4 is set between the heat-insulating metal layer 5 and the pressure device 3 and is connected to the pressure display instrument 2 for real-time reading of the magnitude of the force applied to the microwave material under test; the pressure device 3 includes a metal support frame and a pressure screw, the metal support frame is used to fix and support the pressure sensor 4, and the pressure screw is used to apply pressure to the pressure sensor 14 by screwing it in;

[0034] The surface of the quasi-optical cavity spherical mirror 11 is silver-plated and is positioned directly above the wave-transmitting material 9 to be tested. The normal at the center of the wave-transmitting material 9 to be tested passes through the center of the quasi-optical cavity spherical mirror. The first quasi-optical cavity coaxial coupling ring 12 and the second quasi-optical cavity coaxial coupling ring 13 are symmetrically arranged on the quasi-optical cavity spherical mirror 11, and the first quasi-optical cavity coaxial coupling ring 12 and the second quasi-optical cavity coaxial coupling ring 13 are respectively connected to the two ends of the vector network analyzer 14.

[0035] Example 2

[0036] A method for dielectric testing of wave-transparent materials based on the test system of Example 1 includes the following steps:

[0037] Step 1. Place the first fused silica in the quasi-optical cavity and adjust the distance D between the center of the spherical mirror of the quasi-optical cavity and the plane mirror until a resonance peak appears in the vector network analyzer;

[0038] Step 2. Fix the position of the quasi-optical cavity spherical mirror in Step 1, and test without placing the microwave material to be tested. Heat and pressurize the quasi-optical cavity to the target value. After the temperature and pressure stabilize, use a vector network analyzer to record the resonant frequency f0 when no sample is placed.

[0039] Step 3. Place the microwave material to be tested above the plane mirror, and place a second fused silica on the surface of the microwave material to be tested, keeping the distance D between the center of the quasi-cavity spherical mirror and the plane mirror constant; then heat the microwave material to be tested and the plane mirror to the target value, and wait for the temperature and pressure to stabilize, then use a vector network analyzer to test the resonant frequency f of the material under the required microwave electric field strength. L ;

[0040] Step 4. Based on the resonant frequency f when the material under test is loaded, as measured in Step 3. L Based on the resonant frequency f0 measured in step 2, the dielectric constant ε of the material under test is calculated. r The calculation process is as follows:

[0041]

[0042]

[0043]

[0044]

[0045] Where R0 is the radius of curvature of the quasi-optical cavity, t is the thickness of the material under test, n1 is the refractive index of the sample under test, n2 is the refractive index of fused silica, ω0 is the beam waist radius of the quasi-optical cavity, D is the cavity length of the quasi-optical cavity, c is the electromagnetic wave propagation speed, q is the longitudinal mode number of the resonant electromagnetic field in the quasi-optical cavity, k is the wavenumber when the sample under test is loaded into the quasi-optical cavity, and d, d′, s0, φ D and φ T For intermediate process quantities;

[0046] Solving the above formula yields the dielectric constant ε of the microwave material at a specific temperature and pressure. r .

[0047] If the pressure applied to the sample by the pressurizer remains constant, and the sample is gradually heated, repeating steps 1-4, a series of dielectric constant values ​​ε of the microwave material under test at different temperatures can be measured. rn By plotting the graph using MATLAB, the trend curve of the dielectric constant of the microwave material under test as a function of temperature can be obtained.

[0048] 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 system for testing the dielectric properties of wave-transparent materials under high temperature and high pressure, characterized in that, It includes a temperature display, a pressure display, a pressurizer, a pressure sensor, a heat-insulating metal layer, a plane mirror, a water-cooling unit, a heating induction coil, fused silica, a quasi-optical cavity spherical mirror, a first quasi-optical cavity coaxial coupling ring, a second quasi-optical cavity coupling ring, a vector network analyzer, a temperature controller, and a temperature sensor; The planar mirror, heat-insulating metal layer, pressure sensor, and pressurizer are fixedly connected from top to bottom. The microwave material to be tested is placed on the surface of the planar mirror with the centers of both located on the same vertical line. Fused silica is disposed on the surface of the microwave material to be tested. The bottom surface of the fused silica is flat, and the top surface is curved. The top surface has the same shape as the reflecting surface of the quasi-cavity spherical mirror. The quasi-cavity spherical mirror is positioned directly above the microwave material to be tested, and the normal at the center of the microwave material to be tested passes through the center of the quasi-cavity spherical mirror. The radius of the microwave material to be tested should be greater than the waist radius of the Gaussian beam at the same height. The first quasi-cavity coaxial coupling ring and the second quasi-cavity coaxial coupling ring are symmetrically arranged on the quasi-cavity spherical mirror, and the first quasi-cavity coaxial coupling ring and the second quasi-cavity coaxial coupling ring are respectively connected to the two ends of the vector network analyzer. A heating induction coil is placed on the plane mirror and the microwave material under test. The heating induction coil is connected to a temperature controller, which heats the microwave material under test through induction heating. A water-cooling tank is set inside the heat-insulating metal layer and is connected to a water-cooling unit to reduce the temperature. A temperature sensor is placed on the microwave material under test and connected to a temperature display for real-time measurement and reading of the temperature of the microwave material under test. A pressure display is connected to a pressure sensor to read the magnitude of the force applied to the microwave material under test in real time. A pressurizer is used to pressurize the microwave material under test.

2. The dielectric performance testing system as described in claim 1, characterized in that, The microwave material to be tested is a cuboid with dimensions of 200mm × 200mm × 2mm.

3. The dielectric performance testing system as described in claim 2, characterized in that, The surface of the microwave material to be tested should be smooth and flat to allow the Gaussian beam to propagate as an approximately plane wave in a direction perpendicular to the surface of the microwave material to be tested.

4. The dielectric performance testing system as described in claim 1, characterized in that, The heat-insulating metal layer is made of high-temperature metal.

5. The dielectric performance testing system as described in claim 1, characterized in that, The pressurizer includes a metal support frame and a pressurizing screw. The metal support frame is used to fix and support the pressure sensor, and the pressurizing screw is used to pressurize the pressure sensor.

6. The dielectric performance testing system as described in claim 1, characterized in that, The surface of the quasi-optical cavity spherical mirror is silver-plated.

7. The dielectric performance testing system as described in claim 1, characterized in that, The distance between the center of the quasi-cavity spherical mirror and the plane mirror is D, and the value of D remains constant.

8. A method for testing the dielectric properties of a wave-transparent material under high temperature and high pressure, implemented using the dielectric property testing system for wave-transparent materials under high temperature and high pressure as described in any one of claims 1-7, characterized in that, Includes the following steps: Step 1. Place the first fused silica and adjust the distance between the center of the collimated cavity spherical mirror and the plane mirror. This causes a resonance peak to appear in the vector network analyzer; Step 2. Fix the position of the quasi-optical cavity spherical mirror from Step 1, and perform the test without placing the microwave material to be tested. Heat and pressurize the quasi-optical cavity to the target value. After the temperature and pressure stabilize, use a vector network analyzer to record the resonant frequency when no sample is placed. ; Step 3. Place the microwave material to be tested above the plane mirror, then place the second fused silica, keeping the distance D between the center of the quasi-cavity spherical mirror and the plane mirror constant. Heat the sample and plane mirror to the target value, and after the temperature and pressure stabilize, use a vector network analyzer to test the resonant frequency of the material under the required microwave electric field strength. ; Step 4. Based on the resonant frequency of the material under test measured in Step 3. and the resonant frequency measured in step 2 The dielectric constant of the material under test is calculated. The calculation process is as follows: （1） （2） （3） （4） in, The radius of curvature of the quasi-optical cavity. The thickness of the material to be measured. The refractive index of the sample to be tested is... The refractive index of fused silica is . The beam waist radius of the quasi-optical cavity, For the quasi-optical cavity length, The speed of electromagnetic wave propagation. The longitudinal mode number of the quasi-optical cavity resonant electromagnetic field. The wavenumber when the sample to be tested is loaded into the quasi-optical cavity. , and All are intermediate variables. , For intermediate process quantities; The dielectric constant of the wave-transparent material under specific temperature and pressure can then be obtained. .

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