High and low temperature controllable radar wave-absorbing material reflectivity testing device and method

Abstract

The invention belongs to the technical field of radar wave-absorbing material testing, and provides a high and low temperature controllable radar wave-absorbing material reflectivity testing device and method, and the device comprises a microwave darkroom, a detection mechanism and a tested object placement mechanism which are arranged in the microwave darkroom, and a temperature control mechanism; the detection mechanism comprises a first bracket arranged in the microwave darkroom, and a transmitting antenna and a receiving antenna which are arranged on the first bracket; the tested object placing mechanism comprises a second bracket arranged in the microwave darkroom and a cover body arranged on the second bracket and used for placing a tested object; the temperature control mechanism comprises a temperature control box, and an air inlet pipe and an air return pipe which are connected with the temperature control box; the ends, away from the temperature control box, of the air inlet pipe and the air return pipe are communicated with the interior of the cover body, the air quantity and the air speed entering the cover body are controlled through the temperature control box, the temperature and the humidity in the cover body meet preset requirements, the real environment can be simulated, and the heating uniformity of a tested material can be guaranteed through the arrangement of the cover body.

Description

Technical Field

[0001] The invention belongs to the technical field of radar absorbing material testing, and in particular relates to a high and low temperature controllable reflectivity testing device and method for radar absorbing material. Background Art

[0002] In order to reduce the radar detectability of equipment, radar absorbing materials are used to reduce the reflection of radar waves on the basis of the stealth structure. There are two types of radar absorbing materials in this column. One is the radar absorbing coating applied to the surface of the equipment, and the other is the material suitable for equipment camouflage. The performance of radar absorbing materials, that is, the reflectivity, has a crucial impact on the stealth capability of the equipment. According to relevant requirements, the test methods for the reflectivity of radar absorbing materials mainly include the bow test method and the far-field RCS (Radar Cross Section) test method. Both methods can obtain reliable test results.

[0003] In fact, the working environment of stealth equipment is usually very complex. Different environments such as high cold, high temperature and high humidity may affect the performance of radar absorbing materials. The two existing radar absorbing material reflectivity test methods are both completed under normal indoor temperature environment, which cannot reflect the performance of radar absorbing materials under real environment; and the existing high temperature test method usually heats the material to be tested to a specified temperature and then tests it in an open manner. This method is not only complicated to test, but also may cause test errors due to uneven heating of the material to be tested and temperature changes. Summary of the invention

[0004] In order to solve the above problems, the present invention proposes a high and low temperature controllable radar absorbing material reflectivity testing device and method, the ends of the air inlet duct and the air return duct away from the temperature control box are connected to the interior of the cover body, and the air volume and wind speed entering the cover body are controlled by the temperature control box, so that the temperature and humidity inside the cover body meet the preset requirements, which can simulate the real environment, and the setting of the cover body can ensure the uniformity of heating of the material being tested.

[0005] In order to achieve the above-mentioned purpose, in a first aspect, the present invention provides a high and low temperature controllable radar absorbing material reflectivity testing device, which adopts the following technical scheme: A high and low temperature controllable radar absorbing material reflectivity testing device comprises a microwave darkroom, a detection mechanism and a test object placement mechanism arranged in the microwave darkroom, and a temperature control mechanism; The detection mechanism includes a first bracket arranged in the microwave darkroom, and a transmitting antenna and a receiving antenna arranged on the first bracket; the measured object placement mechanism includes a second bracket arranged in the microwave darkroom, and a cover body arranged on the second bracket for placing the measured object; The temperature control mechanism includes a temperature control box, and an air inlet duct and an air return duct connected to the temperature control box; the ends of the air inlet duct and the air return duct away from the temperature control box are both connected to the interior of the cover body, and the air volume and wind speed entering the cover body are controlled by the temperature control box, so that the temperature and humidity inside the cover body meet preset conditions.

[0006] Furthermore, temperature and humidity sensors are respectively arranged on the upper and lower sides and left and right sides of the return air duct opening at the bottom of the second bracket; when the difference between the maximum temperature and the minimum temperature detected by the four temperature and humidity sensors within a preset continuous time is greater than the preset temperature difference, the air intake speed is increased until the difference is less than or equal to the preset temperature difference, and then the air intake speed is reduced to the initial value; and when the difference between the maximum humidity and the minimum humidity detected by the four temperature and humidity sensors within a preset continuous time is greater than the preset humidity difference, the air intake speed is increased until the difference is less than or equal to the preset humidity difference, and then the air intake speed is reduced to the initial value.

[0007] Furthermore, an absorbing material is provided on the inner wall of the microwave darkroom, and an absorbing screen is provided between the detection mechanism and the mechanism for placing the object to be measured, and the absorbing screen is close to the side of the mechanism for placing the object to be measured.

[0008] Furthermore, the second bracket is made of polymethacrylimide foam material, the air inlet duct and the air return duct are located in the second bracket; and the cover body is made of polymethacrylimide foam material.

[0009] Furthermore, the second bracket is arranged in the microwave darkroom through a turntable; a double-inlet and double-outlet air slip ring is installed at the center of the turntable; two air inlets on the fixed side of the air slip ring are respectively connected to the air inlet pipe and the return air pipe at the temperature control box end; two air inlets on the movable side of the air slip ring are respectively connected to the air inlet pipe and the return air pipe at the first bracket end.

[0010] In order to achieve the above-mentioned purpose, in a second aspect, the present invention also provides a method for testing the reflectivity of radar absorbing materials with controllable high and low temperatures, which adopts the following technical scheme: A method for testing the reflectivity of radar absorbing materials with controllable high and low temperatures, using the device for testing the reflectivity of radar absorbing materials with controllable high and low temperatures as described in the first aspect, comprising: controlling the air volume and wind speed entering the cover body by the temperature control box so that the temperature and humidity in the cover body meet preset conditions.

[0011] Furthermore, without placing the target to be measured, a background test is performed to obtain background frequency sweep data; a metal plate with the same size as the target to be measured is placed to perform a standard body test to obtain standard body frequency sweep data; the target to be measured is placed, and when the set temperature and humidity values ​​are reached inside the cover, the target frequency sweep test data is obtained; the background frequency sweep data is subtracted from the standard body frequency sweep data and the target frequency sweep test data, and after subtracting the background frequency sweep data, software time domain gate operations are performed on the standard body frequency sweep data and the target frequency sweep test data after the background frequency sweep data is subtracted.

[0012] Furthermore, the frequency domain data of the standard body is converted to the time domain through Fourier transformation, the position of the standard body is determined in the time domain, and the gate function is constructed according to the determined position of the standard body; the constructed gate function is added with a Kaiser window, the time domain data of the standard body is multiplied by the gate function after the windowing, and then the time domain data is converted to the frequency domain through inverse Fourier transformation, which is calculated as P m 1.

[0013] Furthermore, the target data is subjected to a software time domain gate operation to obtain the frequency domain data after the software time domain gate processing, which is calculated as P t 1. Calculate the reflectivity of the target: Measured target reflectivity = processed target data P t 1 / Standard volume data P m 1.

[0014] Furthermore, during dual-station measurement, a background test is performed without placing the target to be measured, and background frequency sweeps and data at different dual-station angles are obtained; a dihedral is placed as a dual-station test standard body, and each face of the dihedral is the same size as the target to be measured. The center of the side length of the face of the dihedral where the target to be measured is placed is placed at the center of the turntable. When the incident direction of the electromagnetic wave signal is perpendicular to the face of the dihedral where the target to be measured is placed, the dual-station angle is 0°, and the turntable is controlled to rotate to a set angle. After the rotation is completed, the measuring equipment completes the standard body test at the corresponding dual-station angle, and obtains standard body frequency sweeps and data at different dual-station angles; the target to be measured is placed on the dihedral, and when the set temperature and humidity values ​​are reached, the frequency sweeps of the target to be measured and data at different dual-station angles under the set temperature and humidity environmental conditions are obtained.

[0015] Compared with the prior art, the present invention has the following beneficial effects: 1. In the present invention, the ends of the air inlet duct and the air return duct away from the temperature control box are connected to the interior of the cover body. The air volume and wind speed entering the cover body are controlled by the temperature control box, so that the temperature and humidity inside the cover body meet the preset requirements, which can simulate the real environment, and the setting of the cover body can ensure the uniformity of heating of the material being tested.

[0016] 2. In the present invention, temperature and humidity sensors are respectively arranged on the upper and lower sides and left and right sides of the return air duct opening at the bottom of the second bracket; when the difference between the maximum temperature and the minimum temperature detected by the four temperature and humidity sensors within a preset continuous time is greater than the preset temperature difference, the wind speed is increased to improve the uniformity of mixing of hot air in the cover, thereby ensuring the heating uniformity of each position of the measured target, until the difference is less than or equal to the preset temperature difference, then the air intake speed is reduced to the initial value, avoiding the influence of excessive wind speed on the test results; and, when the difference between the maximum humidity and the minimum humidity detected by the four temperature and humidity sensors within a preset continuous time is greater than the preset humidity difference, the wind speed is increased to improve the uniformity of mixing of hot air in the cover, thereby making the humidity of each area in the cover uniform, until the difference is less than or equal to the preset humidity difference, then the air intake speed is reduced to the initial value, avoiding the problem of a sharp drop in humidity in the cover caused by excessive wind speed affecting the test results.

[0017] 3. In the present invention, the absorbing material is pasted inside the microwave darkroom to avoid the influence of multipath interference inside the microwave darkroom on the test results.

[0018] 4. In the present invention, the second bracket and the cover body are both made of polymethacrylimide foam material, which has extremely low scattering characteristics, ensuring the stability and accuracy of the target under test during the test; the cover body maintains the target under test in a set temperature and humidity environment, and combined with the setting of the absorbing screen, it can effectively reduce the strong reflection caused by the physical object and improve the test accuracy.

[0019] 5. In the present invention, the target is tested under real-time temperature control. In order to better reduce the impact of the environment on the reflectivity measurement, the software time domain gate technology is used in the data process to filter out the background interference signal, thereby improving the reflectivity measurement accuracy.

[0020] 6. The second bracket of the present invention adopts polymethacrylimide foam material. At the same time, in order to better reduce the problem of large reflection of traditional temperature control pipes, the air inlet duct and the air return duct are installed in the form of pre-set holes inside the second bracket, which effectively reduces background interference and provides a guarantee for high-precision reflectivity measurement of radar absorbing materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The drawings in the specification that constitute a part of this embodiment are used to provide a further understanding of this embodiment. The schematic embodiments of this embodiment and their descriptions are used to explain this embodiment and do not constitute improper limitations on this embodiment.

[0022] Figure 1 This is a schematic diagram of the structure of the device according to Embodiment 1 of the present invention; Among them, 1. Microwave darkroom; 101. Absorbing material; 102. Absorbing screen; 2. Detection mechanism; 201. First bracket; 202. Transmitting antenna; 203. Receiving antenna; 204. Preprocessor; 205. Computer; 3. Measured object placement mechanism; 301. Turntable; 302. Second bracket; 303. Cover; 4. Temperature control mechanism; 401. Temperature control box; 402. Air inlet duct; 403. Return air duct; 5. Measured object. DETAILED DESCRIPTION

[0023] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0024] It should be noted that the following detailed descriptions are exemplary and are intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present application belongs.

[0025] Embodiment 1: As described in the background technology, currently, both the bow method and the far-field RCS test method mostly work in an indoor room temperature environment, and do not support reflectivity testing under different temperature and humidity conditions. In addition, the existing high-temperature test method usually heats the material to be tested to a specified temperature and then uses an open method for testing. This method is not only complex to test, but also may cause test errors due to uneven heating of the material to be tested and temperature changes.

[0026] In order to solve at least one of the above problems, Figure 1 As shown, this embodiment provides a high and low temperature controllable radar absorbing material reflectivity test device, based on the conventional far-field RCS test method, using heat-resistant polymethacrylimide (PMI) foam as the design material of the low-scattering target bracket and cover, to achieve real-time and accurate control of the tested material under different temperature and humidity conditions; through the optimization design of the appearance structure and the use of background cancellation, time domain gate and other technologies to effectively suppress background clutter, the reflectivity test accuracy is improved. The optional temperature range is -50℃~100℃, and the humidity range is 5%~95%.

[0027] The device comprises a microwave darkroom 1, a detection mechanism 2, a detection object placement mechanism 3 and a temperature control mechanism 4, etc.

[0028] Optionally, the detection mechanism 2 is arranged at one end of the microwave darkroom 1, and the measured object placement mechanism 3 is arranged at the other end. The microwave darkroom 1 is a rectangular box or other types of structures; an absorbing material 101 is arranged on the inner wall of the microwave darkroom 1, and an absorbing screen 102 is arranged between the detection mechanism 2 and the measured object placement mechanism 3; the absorbing screen 102 is close to the measured object placement mechanism 3.

[0029] Specifically, the microwave darkroom 1 is used to provide a pure shielding environment free from external interference. At the same time, an absorbing material 101 is applied inside the microwave darkroom 1 to prevent the multipath interference inside the microwave darkroom 1 from affecting the test results. Taking 2GHz to 18GHz as an example, the height of the absorbing material 101 applied in the microwave darkroom 1 needs to meet a height of 500mm. In order to meet the far-field test conditions, the size design of the microwave darkroom 1 needs to adapt to the targets of different sizes. According to the far-field test conditions, the test distance is not less than 2D 2 / λ, where D is the size of the target to be measured, and λ is the working wavelength of the electromagnetic wave; taking a 3mm wavelength and a 10GHz working frequency as an example, for a 0.5m-sized target to be measured, the far-field test distance must reach 16.7m. Therefore, the design of the microwave darkroom 1 must be able to accommodate a test distance of at least 16.7m to ensure the effectiveness of the test.

[0030] In order to reduce the size of the microwave darkroom 1, a compact field test method can be used to generate plane waves using a reflective surface at a shorter test distance to achieve a far-field test effect.

[0031] The detection mechanism 2 includes a first bracket 201 disposed in the microwave darkroom 1, a transmitting antenna 202, a receiving antenna 203 and a preprocessor 204 disposed on the first bracket 201, and a computer 205 connected to the preprocessor 204. The preprocessor 204 is provided with a power amplifier and a low noise amplifier.

[0032] Specifically, the detection mechanism 2 is used to realize the generation and reception of radio frequency signals, and its core is a vector network analyzer. When the system dynamic range is insufficient, the system dynamic range can be expanded by adding a power amplifier and a low noise amplifier; in addition, the transmitting antenna 202 and the receiving antenna 203 are used to realize the radiation and reception of radio frequency signals. Considering the subsequent software gating processing, the antenna selects ultra-wideband, such as 2GHz to 18GHz. The computer 205 is used to collect, process and store test signals.

[0033] The object placement mechanism 3 includes a turntable 301 disposed in the microwave darkroom 1, a second bracket 302 disposed on the turntable 301, and a cover 303 disposed on the second bracket 302; a placement table for placing the object 5 to be measured is disposed on the second bracket 302, and the cover 303 is disposed on the placement table. The turntable 301 can be set as a one-dimensional turntable, which can be realized by conventional technology and will not be described in detail here.

[0034] Specifically, the turntable 301 is used to drive the target 5 to rotate, which can obtain the RCS of the target at different angles, and can also realize dual-station testing through dihedral angles, further improving the comprehensiveness and reliability of the test.

[0035] The second bracket 302 can be set as a low-scattering target bracket, used to carry the target 5 and the cover 303; the second bracket 302 can be designed with a lightweight PMI foam material, which not only has excellent bearing capacity but also has extremely low scattering characteristics, ensuring the stability and accuracy of the target during the test; In the design process of the low-scattering target bracket, the method of penetrating air ducts inside the PMI foam is used instead of the traditional method of using return air ducts. This can effectively reduce the strong reflection caused by the object and improve the test accuracy.

[0036] Specifically, the cover 303 is used to maintain the target 5 under test in a set temperature and humidity environment. In order to reduce reflection interference during the test, the cover 303 can be made of low-density PMI foam material. Under the condition of achieving the set thermal insulation, the density of the selected PMI foam material is as low as possible. Considering the plane irradiation of electromagnetic waves, the cover 303 adopts a cubic shape. In order to reduce its reflection effect, the software time domain gate technology is used. At the same time, the bottom of the cover 303 needs to be tightly attached to the second bracket 302 to ensure the efficiency of temperature control.

[0037] The temperature control mechanism 4 includes a temperature control box 401 , and an air inlet pipe 402 and an air return pipe 403 connected to the temperature control box 401 . The air inlet pipe 402 and the air return pipe 403 are connected to the interior of the cover body 303 after passing through the second bracket 302 .

[0038] Specifically, the temperature control box 401 is used to control the temperature and humidity inside the cover body 303, wherein the selection of the temperature control box 401 is mainly configured according to the efficiency of heating and cooling; a temperature and humidity sensor can be placed at the return air duct at the bottom of the second bracket 302 to monitor whether the temperature inside the cover body 303 meets the set conditions.

[0039] A double-inlet and double-outlet air slip ring is installed at the center of the turntable 301; the two air inlets on the fixed side of the air slip ring are respectively connected to the air inlet pipe 402 and the return air pipe 403 at the temperature control box 401 end, and the two air inlets on the movable side of the air slip ring are respectively connected to the air inlet pipe 402 and the return air pipe 403 at the second bracket 302 end; the connection on the movable side of the air slip ring rotates with the turntable 301.

[0040] A standard body is provided for the calibration of reflectivity measurement. The device in this embodiment is mainly oriented toward radar absorbing materials, so the standard body may be a metal flat plate or a dihedral angle selected for dual-station testing.

[0041] The computer 205 is also connected to the object placement mechanism 3 and the temperature control mechanism 4, and is used to coordinately control the detection mechanism 2, the turntable 301 and the temperature control box 401, etc., to complete the radar absorbing material reflectivity test at different temperatures, different humidities, different frequencies, and different dual-station angles.

[0042] In this embodiment, based on the test device, a method for testing the reflectivity of radar absorbing materials with controllable high and low temperatures is also provided, and the process is as follows: S1. Single station measurement: S1.1. According to Figure 1 Connect the device and, after the connection is complete, preheat the equipment.

[0043] S1.2. Without placing the target 5, the computer 205 controls the detection mechanism 2 to perform a background test. The background test needs to include the cover 303 to obtain background frequency scanning data, which is calculated as b j .

[0044] S1.3. Place a metal plate of the same size as the target 5. The computer 205 controls the detection mechanism 2 to perform a standard body test and obtain the standard body frequency sweep data, which is calculated as P m .

[0045] S1.4, place the target 5 to be tested, the computer 205 sets the working temperature and humidity of the temperature control box 401, obtains the temperature and humidity sensor data in real time, and when the set temperature and humidity values ​​are reached, controls the detection mechanism 2 to perform the test, obtains the target frequency sweep test data, and calculates it as P t .

[0046] S1.4.1. Temperature and humidity sensors are respectively arranged on the upper and lower sides and left and right sides of the return air duct opening at the bottom of the second bracket 302; when the difference between the maximum temperature and the minimum temperature detected by the four temperature and humidity sensors within a preset continuous time is greater than the preset temperature difference, it indicates that there is a difference in temperature at different positions in the cover body 303, and the heating of the measured target 5 is uneven. In order to ensure the uniformity of heating of the measured target 5, the air intake speed is increased. By increasing the wind speed, the uniformity of mixing of hot air in the cover body 303 is improved, thereby ensuring the uniformity of heating of each position of the measured target 5, until the difference is less than or equal to the preset temperature difference, then the air intake speed is reduced to the initial value to avoid the influence of excessive wind speed on the test results.

[0047] S1.4.2. When the difference between the maximum humidity and the minimum humidity detected by the four temperature and humidity sensors within the preset continuous time is greater than the preset humidity difference, it means that there is a difference in humidity at different positions in the cover body 303, and the environments at different positions of the target 5 to be measured are different. In order to ensure the uniformity of the environments at various positions of the target 5 to be measured, the air intake speed is increased. By increasing the wind speed, the uniformity of mixing of hot air in the cover body 303 is improved, so that the humidity in various areas of the cover body 303 is uniform. After the difference is less than or equal to the preset humidity difference, the air intake speed is reduced to the initial value to avoid the problem of a sharp drop in humidity in the cover body 303 due to excessive wind speed, which affects the test results.

[0048] S1.5. Process the data: The background frequency sweep data is subtracted from the standard frequency sweep data and the target frequency sweep test data. After the background frequency sweep data is subtracted, a software time domain gate operation is performed on the standard frequency sweep data and the target frequency sweep test data after the background frequency sweep data is subtracted.

[0049] S1.6. Perform software time domain gate operation on standard volume sweep data: S1.6.1. Convert the frequency domain data of the standard body into the time domain through Fourier transform, determine the position of the standard body in the time domain, and construct a gate function based on the position. In order to minimize multipath interference, the equipment working bandwidth is as wide as possible. Taking 2GHz to 18GHz as an example, the gate width of the constructed gate function is set to 0.5ns.

[0050] S1.6.2. Add a Kaiser window to the constructed gate function, with the coefficient set to 6. Multiply the time domain data of the standard volume by the gate function after adding the window. Then, perform an inverse Fourier transform on the time domain data to convert it into the frequency domain, which is calculated as P m1 .

[0051] S1.7, repeat step S1.6 for the target data to obtain the frequency domain data after the software time domain gate processing, calculated as P t1, calculate the reflectivity of the target according to the following formula: Measured target reflectivity = processed target data P t1 / Standard volume data P m1 .

[0052] S2, dual-station measurement includes the following test steps: S2.1. According to Figure 1 Connect the device and, after the connection is complete, preheat the equipment.

[0053] S2.2, without placing the target 5, the computer 205 controls the detection mechanism 2 and the turntable 301 to perform background testing. The background test needs to include the cover 303 to obtain background frequency scanning and different dual-station angles. θ The following data, the bi-station angle needs to be consistent with the bi-station angle of the standard body and target test later, calculated as b jθ .

[0054] S2.3. Place the dihedral angle as a standard body for dual-station test. Each face of the dihedral angle needs to be the same size as the target to be measured. Place the side length center of the face of the dihedral angle where the target to be measured 5 is placed at the center of the turntable 301. When the incident direction of the electromagnetic wave signal is perpendicular to the face of the dihedral angle where the target to be measured 5 is placed, the dual-station angle is 0°, corresponding to a single-station test. If the dual-station angle θ needs to be tested, the computer 205 controls the turntable 301 to rotate to a set angle. θ After the rotation is completed, the corresponding dual-station angle is completed by microwave measurement equipment θ Repeat the above process to complete the standard body test under various dual-station angles, and obtain the standard body sweep frequency, different dual-station angles θ Data, counted as P mθ .

[0055] S2.4, place the target 5 on the dihedral angle, the computer 205 sets the working temperature and humidity of the temperature control box 401, and obtains the temperature and humidity sensor data in real time. When the set temperature and humidity values ​​are reached, repeat the test process of step S2.3 to complete the set dual-station angles. θ The target test under the set temperature and humidity environment conditions is obtained, and the data under different dual-station angles are calculated as P tθ .

[0056] S2.5. Process the data: subtract the background data from the calibration volume data and the target data respectively. After subtracting the background data, perform a software time domain gate operation on the calibration volume data and the target data after subtracting the background data respectively.

[0057] S2.6. Perform software time domain gate operation on standard volume data: S2.6.1. Convert the frequency domain data of the standard body into the time domain through Fourier transform, determine the position of the standard body in the time domain, and construct a gate function based on the position. In order to minimize multipath interference, the equipment working bandwidth is as wide as possible. Taking 2GHz to 18GHz as an example, the gate width of the constructed gate function is set to 0.5ns.

[0058] S2.6.2. Add a Kaiser window to the constructed gate function, with the coefficient set to 6. Multiply the time domain data of the standard volume by the gate function after adding the window. Then, perform an inverse Fourier transform on the time domain data to convert it into the frequency domain, which is calculated as P mθ1 .

[0059] S2.7, repeat step S2.6 for the target data to obtain the frequency domain data after the software time domain gate processing, calculated as P tθ1 , calculate the reflectivity of the target according to the following formula: Measured target reflectivity = processed target data P tθ1 / Standard volume data P mθ1 .

[0060] If it is necessary to conduct reflectivity tests under multiple temperature and humidity environments, the computer 205 needs to coordinately control the temperature control box 401, the turntable 301 and the detection mechanism 2. In the above-mentioned single-station and dual-station test system processes, the computer 205 needs to automatically complete the target reflectivity test under different temperature and humidity environmental conditions under the single-station and dual-station working systems according to the pre-set multiple temperature and humidity environmental conditions. The whole process is fully automated. The computer 205 controls the temperature control box 401. When it senses that the temperature and humidity in the cover body 303 reach the preset environmental conditions, the above-mentioned single-station and dual-station test steps are automatically executed to guide the completion of all tests under the preset temperature and humidity environmental conditions.

[0061] The above description is only a preferred embodiment of the present embodiment and is not intended to limit the present embodiment. For those skilled in the art, the present embodiment may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present embodiment shall be included in the protection scope of the present embodiment.

Claims

1. A high and low temperature controllable radar absorbing material reflectivity testing device, characterized in that: It includes a microwave darkroom, a detection mechanism and a detection object placement mechanism arranged in the microwave darkroom, and a temperature control mechanism; The detection mechanism includes a first bracket arranged in the microwave darkroom, and a transmitting antenna and a receiving antenna arranged on the first bracket; the measured object placement mechanism includes a second bracket arranged in the microwave darkroom, and a cover body arranged on the second bracket for placing the measured object; The temperature control mechanism includes a temperature control box, and an air inlet duct and an air return duct connected to the temperature control box; the ends of the air inlet duct and the air return duct away from the temperature control box are both connected to the interior of the cover body, and the air volume and wind speed entering the cover body are controlled by the temperature control box, so that the temperature and humidity inside the cover body meet preset conditions.

2. A high and low temperature controllable radar absorbing material reflectivity testing device as claimed in claim 1, characterized in that: Temperature and humidity sensors are respectively arranged on the upper and lower sides and the left and right sides of the return air duct opening at the bottom of the second bracket; when the difference between the maximum temperature and the minimum temperature detected by the four temperature and humidity sensors within a preset continuous time is greater than the preset temperature difference, the air intake speed is increased until the difference is less than or equal to the preset temperature difference, and then the air intake speed is reduced to the initial value; Furthermore, when the difference between the maximum humidity and the minimum humidity detected by the four temperature and humidity sensors within a preset continuous time is greater than a preset humidity difference, the air intake speed is increased until the difference is less than or equal to the preset humidity difference, and then the air intake speed is reduced to the initial value.

3. The high and low temperature controllable radar absorbing material reflectivity testing device as claimed in claim 1, characterized in that: The inner wall of the microwave darkroom is provided with a wave-absorbing material, and a wave-absorbing screen is provided between the detection mechanism and the mechanism for placing the measured object, and the wave-absorbing screen is close to the side of the mechanism for placing the measured object.

4. A high and low temperature controllable radar absorbing material reflectivity testing device as claimed in claim 3, characterized in that: The second bracket is made of polymethacrylimide foam material, the air inlet pipe and the air return pipe are located in the second bracket; the cover body is made of polymethacrylimide foam material.

5. The high and low temperature controllable radar absorbing material reflectivity testing device as claimed in claim 1, characterized in that: The second bracket is arranged in the microwave darkroom through a turntable; a double-inlet and double-outlet air slip ring is installed at the center of the turntable; two air inlets on the fixed side of the air slip ring are respectively connected to the air inlet pipe and the return air pipe at the temperature control box end; two air inlets on the movable side of the air slip ring are respectively connected to the air inlet pipe and the return air pipe at the first bracket end.

6. A method for testing the reflectivity of radar absorbing materials with controllable high and low temperatures, characterized in that: The high and low temperature controllable radar absorbing material reflectivity testing device as described in any one of claims 1 to 5 is used, including: controlling the air volume and wind speed entering the cover body through the temperature control box so that the temperature and humidity in the cover body meet preset conditions.

7. A method for testing the reflectivity of radar absorbing materials with controllable high and low temperatures as claimed in claim 6, characterized in that: Without placing the target to be tested, perform background test to obtain background frequency sweep data; Place a metal plate with the same size as the target to be measured to perform a standard body test and obtain standard body frequency sweep data; Place the target to be tested, and when the temperature and humidity inside the cover reach the set values, obtain the target frequency sweep test data; The background frequency sweep data is subtracted from the standard frequency sweep data and the target frequency sweep test data. After the background frequency sweep data is subtracted, a software time domain gate operation is performed on the standard frequency sweep data and the target frequency sweep test data after the background frequency sweep data is subtracted.

8. A method for testing the reflectivity of radar absorbing materials with controllable high and low temperatures as claimed in claim 7, characterized in that: The frequency domain data of the standard body is converted to the time domain through Fourier transformation, the position of the standard body is determined in the time domain, and the gate function is constructed according to the determined position of the standard body; the constructed gate function is added with a Kaiser window, the time domain data of the standard body is multiplied by the gate function after the windowing, and then the time domain data is inversely Fourier transformed into the frequency domain, which is calculated as P m 1.

9. A method for testing the reflectivity of radar absorbing materials with controllable high and low temperatures as claimed in claim 8, characterized in that: Perform software time domain gate operation on the target data to obtain the frequency domain data after software time domain gate processing, which is calculated as P t 1. Calculate the reflectivity of the target: Measured target reflectivity = processed target data P t 1 / Standard volume data P m 1.

10. A method for testing the reflectivity of radar absorbing materials with controllable high and low temperatures as claimed in claim 6, characterized in that: During dual-station measurement, background testing is performed without placing the target to be measured, and background frequency sweeping and data at different dual-station angles are obtained; a dihedral is placed as a dual-station test standard body, and each face of the dihedral is the same size as the target to be measured. The center of the side length of the face of the dihedral where the target to be measured is placed is placed at the center of the turntable. When the incident direction of the electromagnetic wave signal is perpendicular to the face of the dihedral where the target to be measured is placed, the dual-station angle is 0°, and the turntable is controlled to rotate to a set angle. After the rotation is completed, the measuring equipment completes the standard body test at the corresponding dual-station angle, and obtains standard body frequency sweeping and data at different dual-station angles; the target to be measured is placed on the dihedral, and when the set temperature and humidity values ​​are reached, the frequency sweeping of the target to be measured and the data at different dual-station angles under the set temperature and humidity environmental conditions are obtained.

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