A high and low temperature controllable radar absorbing material reflectivity testing device and method

Abstract

The present invention belongs to the technical field of radar absorbing material testing, and proposes a high- and low-temperature controllable reflectivity testing device and method for radar absorbing materials, comprising 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 comprises a first bracket arranged in the microwave darkroom, and a transmitting antenna and a receiving antenna arranged on the first bracket; the test object placement mechanism comprises a second bracket arranged in the microwave darkroom, and a cover body arranged on the second bracket for placing the test object; the temperature control mechanism comprises 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 requirements, can simulate a real environment, and the setting of the cover body can ensure the uniformity of heating of the test material.

Description

Technical Field

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

[0002] To reduce radar detectability, radar-absorbing materials are used in addition to stealth structures to minimize radar reflection. These materials fall into two categories: radar-absorbing coatings applied to the surface of the equipment, and materials used for camouflage. The performance of radar-absorbing materials, specifically their reflectivity, plays a crucial role in determining a device's stealth capabilities. According to relevant requirements, radar-absorbing material reflectivity testing primarily involves the bow test and the far-field RCS (Radar Cross Section) test, both of which yield reliable 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 return air duct away from the temperature control box are both connected to the interior of the cover. The temperature control box controls the air volume and wind speed entering the cover, so that the temperature and humidity inside the cover meet the preset requirements, which can simulate the real environment. In addition, the setting of the cover can ensure the uniformity of heating of the material being tested.

[0005] To achieve the above objectives, in a first aspect, the present invention provides a high and low temperature controllable reflectivity testing device for radar absorbing materials, which adopts the following technical solutions:

[0006] 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;

[0007] 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 object placement mechanism includes a second bracket arranged in the microwave darkroom, and a cover body arranged on the second bracket for placing the object to be measured;

[0008] 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 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.

[0009] 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.

[0010] 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.

[0011] Furthermore, the second bracket is made of polymethacrylimide foam material, the air inlet pipe and the air return pipe are located in the second bracket; and the cover body is made of polymethacrylimide foam material.

[0012] 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; the 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; the 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.

[0013] In order to achieve the above-mentioned purpose, in a second aspect, the present invention further provides a method for testing the reflectivity of radar absorbing materials with controllable high and low temperatures, which adopts the following technical solutions:

[0014] A method for testing the reflectivity of radar absorbing materials with controllable high and low temperatures uses the device for testing the reflectivity of radar absorbing materials with controllable high and low temperatures as described in the first aspect, and includes: controlling the air volume and wind speed entering the enclosure through the temperature control box so that the temperature and humidity inside the enclosure meet preset conditions.

[0015] Furthermore, without placing the target to be measured, a background test is performed to obtain background frequency sweep data; a metal plate of 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 subtracting the background frequency sweep data.

[0016] Furthermore, the frequency domain data of the standard body is converted to the time domain through Fourier transform, the position of the standard body is determined in the time domain, and a gate function is constructed according to the position of the determined standard body; a Caesar window is added to the constructed gate function, the time domain data of the standard body is multiplied by the windowed gate function, and then the time domain data is inverse Fourier transformed to the frequency domain, which is calculated as P m 1.

[0017] 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:

[0018] Measured target reflectivity = processed target data P t 1 / Standard body data P m 1.

[0019] Furthermore, during dual-station measurement, background testing 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 on which the target to be measured 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 on which 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.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] 1. In the present invention, 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. The temperature control box controls the air volume and wind speed entering the cover so that the temperature and humidity inside the cover meet the preset requirements, which can simulate the real environment. In addition, the setting of the cover can ensure the uniformity of heating of the material being tested.

[0022] 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 excessive wind speed causing a sharp drop in humidity in the cover to affect the test results.

[0023] 3. In the present invention, the absorbing material is applied inside the microwave darkroom, thereby preventing the multipath interference inside the microwave darkroom from affecting the test results.

[0024] 4. In the present invention, the second bracket and the cover are both made of polymethacrylimide foam material, which has extremely low scattering characteristics, ensuring the stability and accuracy of the target during the test; the cover maintains the target 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.

[0025] 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.

[0026] 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 and return ducts 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

[0027] The drawings constituting a part of the specification of this embodiment are used to provide a further understanding of this embodiment. The schematic embodiments and descriptions of this embodiment are used to explain this embodiment and do not constitute an improper limitation on this embodiment.

[0028] Figure 1 Schematic diagram of the device structure of Example 1 of the present invention;

[0029] 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 target. DETAILED DESCRIPTION

[0030] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0031] 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 meaning as commonly understood by those skilled in the art to which the present application belongs.

[0032] Example 1:

[0033] As discussed in the background, both the bow method and far-field RCS testing methods currently operate in indoor environments at room temperature and do not support reflectance testing under varying temperature and humidity conditions. Furthermore, existing high-temperature testing methods typically heat the material under test to a specified temperature and then conduct the test in an open-circuit environment. This method is not only complex but can also introduce measurement errors due to uneven heating and temperature fluctuations.

[0034] 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 conventional far-field RCS test methods, it uses heat-resistant polymethacrylimide (PMI) foam as the design material for the low-scattering target bracket and cover. This allows for real-time and precise control of the tested material under varying temperature and humidity conditions. Through optimized structural design and the use of background cancellation and time-domain gating techniques, background clutter is effectively suppressed, improving reflectivity test accuracy. The selectable temperature range is -50°C to 100°C, and the humidity range is 5% to 95%.

[0035] The device includes a microwave darkroom 1, a detection mechanism 2, a detection object placement mechanism 3, a temperature control mechanism 4, and the like.

[0036] Optionally, the detection mechanism 2 is disposed at one end of the microwave anechoic chamber 1, and a test object placement mechanism 3 is disposed at the other end. The microwave anechoic chamber 1 is a rectangular box or other type of structure; absorbing material 101 is disposed on the inner wall of the microwave anechoic chamber 1, and an absorbing screen 102 is disposed between the detection mechanism 2 and the test object placement mechanism 3; the absorbing screen 102 is located near the test object placement mechanism 3.

[0037] Specifically, the microwave darkroom 1 is used to provide a pure shielded 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 in the microwave darkroom 1 needs to meet 500mm.

[0038] In order to meet the far-field test conditions, the size design of the microwave darkroom 1 needs to adapt to the different sizes of the test targets. 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 being measured and λ is the operating wavelength of the electromagnetic wave. Taking a 3mm wavelength and a 10GHz operating frequency as an example, for a 0.5m target, the far-field test distance must reach 16.7m. Therefore, the microwave anechoic chamber 1 must be designed to accommodate a test distance of at least 16.7m to ensure test effectiveness.

[0039] In order to reduce the size of the microwave anechoic chamber 1, a compact field test method can be used to generate plane waves using a reflecting surface at a shorter test distance to achieve the effect of far-field testing.

[0040] 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.

[0041] Specifically, the detection mechanism 2 is used to generate and receive RF signals. Its core is a vector network analyzer. If the system's dynamic range is insufficient, this can be expanded by adding a power amplifier and a low-noise amplifier. Furthermore, the transmitting antenna 202 and the receiving antenna 203 are used to radiate and receive RF signals. Considering subsequent software gating, the antennas are designed to operate in ultra-wideband (e.g., 2 GHz to 18 GHz). The computer 205 is used to collect, process, and store test signals.

[0042] The object placement mechanism 3 includes a turntable 301 disposed within the microwave anechoic chamber 1, a second support 302 disposed on the turntable 301, and a cover 303 disposed on the second support 302. A placement platform for the object 5 to be measured is disposed on the second support 302, and the cover 303 is disposed on the placement platform. The turntable 301 can be configured as a one-dimensional turntable and can be implemented using conventional techniques, which will not be described in detail here.

[0043] Specifically, the turntable 301 is used to rotate the target 5 to obtain the RCS of the target at different angles, and also to achieve dual-station testing through dihedral angles, thereby further improving the comprehensiveness and reliability of the test.

[0044] The second bracket 302 can be configured as a low-scattering target bracket for carrying 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 load-bearing capacity but also has extremely low scattering characteristics, ensuring the stability and accuracy of the target during the test.

[0045] In the design process of the low-scattering target bracket, the method of using air ducts inside the PMI foam instead of the traditional method of using return air ducts can effectively reduce the strong reflection caused by the physical object and improve the test accuracy.

[0046] Specifically, the cover 303 is used to maintain the target 5 under test within a set temperature and humidity environment. To reduce reflection interference during testing, the cover 303 can be made of low-density PMI foam material. While achieving the set thermal insulation, the selected PMI foam material density should be as low as possible. Considering the planar irradiation of electromagnetic waves, the cover 303 adopts a cubic shape. To reduce its reflection effect, software time-domain gating 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 efficient temperature control.

[0047] 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 respectively pass through the second bracket 302 and communicate with the interior of the cover body 303 .

[0048] 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.

[0049] A double-inlet and double-outlet air slip ring is installed in 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.

[0050] A standard body is provided for reflectivity measurement calibration. The device in this embodiment is mainly oriented towards radar absorbing materials, so the standard body can be a metal flat plate or a dihedral angle selected for dual-station testing.

[0051] The computer 205 is also connected to the object placement mechanism 3 and the temperature control mechanism 4 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.

[0052] 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. The process is as follows:

[0053] S1. Single station measurement:

[0054] S1.1, in accordance with Figure 1 Connect the device and, after the connection is complete, preheat the equipment.

[0055] 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 sweep data, which is calculated as b j .

[0056] 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 sweep frequency data, which is calculated as P m .

[0057] S1.4. Place the target 5, and the computer 205 sets the operating 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, the detection mechanism 2 is controlled to perform the test and obtain the target sweep test data, which is calculated as P t .

[0058] S1.4.1. Temperature and humidity sensors are respectively set on the upper and lower sides and left and right sides of the return air duct 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 is greater than the preset temperature difference within a preset continuous time, it indicates that there is a temperature difference at different positions in the cover body 303, and the heating of the target 5 to be measured is uneven. In order to ensure the uniformity of heating 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, thereby ensuring the uniformity of heating of each position of the target 5 to be measured. After the difference is less than or equal to the preset temperature difference, the air intake speed is reduced to the initial value to avoid the influence of excessive wind speed on the test results.

[0059] S1.4.2. 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, it indicates that there is a difference in humidity at different positions in the cover body 303, and the environments at different positions of the measured target 5 are different. In order to ensure the uniformity of the environments at various positions 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 making the humidity of various areas in the cover body 303 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 caused by excessive wind speed, which affects the test results.

[0060] S1.5. Process the data:

[0061] The background sweep data is subtracted from the standard body sweep data and the target sweep test data. After the background sweep data is subtracted, a software time domain gate operation is performed on the standard body sweep data and the target sweep test data after the background sweep data is subtracted.

[0062] S1.6. Perform software time domain gate operation on the standard volume sweep data:

[0063] 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. To minimize multipath interference, the device operating bandwidth is as wide as possible. For example, in the range of 2 GHz to 18 GHz, the gate width of the constructed gate function is set to 0.5 ns.

[0064] S1.6.2. Add a Caesar window to the constructed gate function with a coefficient of 6. Multiply the time domain data of the standard volume by the windowed gate function. Then, perform an inverse Fourier transform on the time domain data to convert it into the frequency domain. P m1 .

[0065] S1.7. Repeat step S1.6 for the target data to obtain the frequency domain data after the software time domain gate processing, which is calculated as Pt1 , calculate the reflectivity of the target according to the following formula:

[0066] Measured target reflectivity = processed target data P t1 / Standard body data P m1 .

[0067] S2, dual-station measurement includes the following test steps:

[0068] S2.1, according to Figure 1 Connect the device and, after the connection is complete, preheat the equipment.

[0069] 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, calculated as b jθ .

[0070] S2.3. Place the dihedral angle as a standard for dual-station testing. Each face of the dihedral angle needs to be the same size as the target to be tested. Place the center of the side length of the face of the dihedral angle where the target to be tested 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 tested 5 is placed, the dual-station angle is 0°, corresponding to a single-station test. If a 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 .

[0071] 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 by scanning the target frequency and obtaining data at different dual-station angles, which is calculated as P tθ .

[0072] 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.

[0073] S2.6. Perform software time-domain gate operation on standard volume data:

[0074] 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. To minimize multipath interference, the device operating bandwidth is as wide as possible. For example, in the range of 2 GHz to 18 GHz, the gate width of the constructed gate function is set to 0.5 ns.

[0075] S2.6.2. Add a Caesar window to the constructed gate function with a coefficient of 6. Multiply the time domain data of the standard volume by the windowed gate function. Then, perform an inverse Fourier transform on the time domain data to convert it into the frequency domain. P mθ1 .

[0076] S2.7. Repeat step S2.6 for the target data to obtain the frequency domain data after the software time domain gate processing, which is calculated as P tθ1 , calculate the reflectivity of the target according to the following formula:

[0077] Measured target reflectivity = processed target data P tθ1 / Standard body data P mθ1 .

[0078] If reflectivity tests under multiple temperature and humidity environments are required, the computer 205 needs to coordinately control the temperature control box 401, turntable 301, and detection mechanism 2. In the above-mentioned single-station and dual-station testing system processes, the computer 205 needs to automatically complete the target reflectivity tests under different temperature and humidity environmental conditions in both single-station and dual-station working systems according to the multiple pre-set temperature and humidity environmental conditions. The entire process is fully automated. The computer 205 controls the temperature control box 401. When it senses that the temperature and humidity inside the cover 303 have reached the preset environmental conditions, it automatically executes the above-mentioned single-station and dual-station testing steps, guiding the completion of the tests under all preset temperature and humidity environmental conditions.

[0079] The above description is merely a preferred embodiment of this embodiment and is not intended to limit this embodiment. Those skilled in the art will readily appreciate that this embodiment may be modified and varied in various ways. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of this embodiment shall be within the scope of protection of this embodiment.

Claims

1. A method for testing the reflectivity of radar absorbing materials with controllable high and low temperatures, characterized in that: A high and low temperature controllable radar absorbing material reflectivity testing device is used, comprising 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 disposed in the microwave darkroom, and a transmitting antenna and a receiving antenna disposed on the first bracket; the measured object placement mechanism includes a second bracket disposed in the microwave darkroom, and a cover disposed on the second bracket for placing the measured object; the second bracket and the cover are made of polymethacrylimide foam material; the second bracket is disposed in the microwave darkroom via a turntable; a double-inlet and double-outlet air slip ring is installed at the center of the turntable; Set up a standard body for reflectivity measurement calibration. The standard body can be a metal plate or a dihedral angle selected for dual-station testing. 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 of the determined standard body. Add a Caesar window to the constructed gate function, multiply the time domain data of the standard body by the windowed gate function, and then perform inverse Fourier transform on the time domain data to convert it into the frequency domain. P m 1; 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: reflectivity of the target = processed target data P t 1 / Standard volume data P m 1; 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 air inlet duct and the air return duct are both connected to the interior of the cover at one end away from the temperature control box, and the air volume and wind speed entering the cover are controlled by the temperature control box so that the temperature and humidity inside the cover meet preset conditions; Temperature and humidity sensors are respectively provided 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 is greater than the preset temperature difference within a preset continuous time, 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; Also, 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.

2. The method for testing the reflectivity of radar absorbing materials with controllable high and low temperatures according to claim 1, wherein: 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.

3. The method for testing the reflectivity of radar absorbing materials with controllable high and low temperatures according to claim 2, wherein: The air inlet duct and the air return duct are located in the second bracket.

4. The method for testing the reflectivity of a radar absorbing material with controllable high and low temperatures according to any one of claims 1 to 3, comprising: The temperature control box controls the air volume and speed entering the cover so that the temperature and humidity inside the cover meet preset conditions.

5. The method for testing the reflectivity of radar absorbing materials with controllable high and low temperatures according to claim 4, wherein: Without placing the target to be measured, perform background testing 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 sweep frequency data; Place the target to be measured, and when the temperature and humidity inside the cover reach the set values, obtain the target sweep test data; The background sweep data is subtracted from the standard body sweep data and the target sweep test data. After the background sweep data is subtracted, a software time domain gate operation is performed on the standard body sweep data and the target sweep test data after the background sweep data is subtracted.

6. The method for testing the reflectivity of radar absorbing materials with controllable high and low temperatures according to claim 4, wherein: During dual-station measurement, background testing 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.

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