A calibration method for high and low temperature microwave attenuation characteristics of a testing device

Abstract

A method for calibrating the high and low temperature microwave attenuation characteristics of a test device in the field of high-power radiation source power testing technology is disclosed. The method involves detecting the power performance of the test device in the 1GHz–40GHz frequency band and at an ambient temperature of -55℃–75℃ using a transmitting antenna I. The test device includes absorbing material, a microwave link, and a receiving antenna I. A transparent temperature chamber provides a temperature environment of -55℃–75℃, with a temperature control accuracy of ≤±2℃, temperature fluctuation of ≤±0.5℃, and temperature uniformity of ≤2℃. A transparent window is provided on one side of the transparent temperature chamber. The method includes the following steps: S1, testing the components affecting the high and low temperature characteristics of the test device; S2, parameter calibration; and S3, traceability. This invention achieves accurate calibration and traceability of the microwave attenuation characteristics of the test device under high and low temperature environmental conditions, thereby providing a corrective reference for the power test results of high-power radiation sources under high and low temperature environments.

Description

Technical Field

[0001] This invention relates to the field of high-power radiation source power testing technology, and in particular to a method for calibrating the high and low temperature microwave attenuation characteristics of a testing device. Background Technology

[0002] As is well known, high-power radiation sources are mainly used to provide high-power signals to interfere with communication and radar signals in situations where shielding is required. For example, they can be used as interference radiation sources in examination rooms or to provide test signals during electromagnetic compatibility testing of various electronic products. During power testing of high-power radiation sources, a dedicated testing device is needed to assess the attenuation and shielding performance of the high-power radiation source at room temperature, low temperature, and high temperature. Tests have revealed that the test results of high-power radiation sources under high and low temperature conditions are significantly different from those at room temperature. To accurately determine whether the changes in the test results of high-power radiation source products are caused by the high-power radiation source products themselves or by the performance of the testing device, it is urgent to calibrate the microwave attenuation characteristics of the testing device under high and low temperature environments relative to room temperature environments. Summary of the Invention

[0003] To overcome the shortcomings of the prior art, the present invention discloses a method for calibrating the high and low temperature microwave attenuation characteristics of a testing device.

[0004] To achieve the above-mentioned objectives, the present invention adopts the following technical solution:

[0005] A method for calibrating the high and low temperature microwave attenuation characteristics of a testing device, wherein the power performance of the testing device in the 1GHz to 40GHz frequency band and the ambient temperature range of -55℃ to 75℃ is detected by transmitting antenna I. The testing device includes absorbing material for the device, a microwave link, and receiving antenna I. The microwave-transparent chamber calibration testing system includes an industrial control computer, a vector network analyzer, and a microwave-transparent chamber. The microwave-transparent chamber provides a temperature environment of -55℃ to 75℃, with a temperature control accuracy of ≤±2℃, a temperature fluctuation of ≤±0.5℃, and a temperature uniformity of ≤2℃. The inside of the microwave-transparent chamber is lined with environmental absorbing material to improve the material testing environment, and a microwave-transparent window is provided on one side of the chamber. The method includes the following steps:

[0006] S1. Testing of the influence of high and low temperature characteristics of the testing device:

[0007] High and low temperature reflectivity test of absorbing material for S1.1 device:

[0008] The device's absorbing material is placed inside a wave-transparent temperature chamber. An arc-shaped slide rail is built on the side of the wave-transparent temperature chamber with a wave-transparent window, so that the center of the arc-shaped slide rail falls on the device's absorbing material. A transmitting antenna II and a receiving antenna II, which can slide along the arc-shaped slide rail, are installed at both ends of the arc-shaped slide rail, respectively, and the central angle of the arc-shaped slide rail is 60°. An absorbing screen is placed around the outside of the arc-shaped slide rail, and the side of the wave-transparent temperature chamber with the wave-transparent window passes through the corresponding absorbing screen. A vector network analyzer controlled by an industrial control computer is set up outside the absorbing screen, and the transmitting antenna II and the receiving antenna II are connected to the corresponding signals of the vector network analyzer. The reflectivity of the device's absorbing material under different temperature environments is detected by the vector network analyzer.

[0009] S1.2 High and low temperature characteristics test of receiving antenna I and transmitting antenna I:

[0010] The receiving antenna I is placed inside the wave-transparent temperature chamber. A standard horn antenna of the same specifications as the receiving antenna I is set on the side of the wave-transparent temperature chamber with a wave-transparent window. An absorbing screen is placed around the standard horn antenna, and the side of the wave-transparent temperature chamber with a wave-transparent window passes through the corresponding absorbing screen. A vector network analyzer controlled by an industrial control computer is set on the outside of the absorbing screen. The receiving antenna I and the standard horn antenna are connected to the corresponding signals of the vector network analyzer. The gain change of the receiving antenna I under different temperature environments is detected by the vector network analyzer.

[0011] The transmitting antenna I is placed inside a wave-transparent temperature chamber. A standard horn antenna of the same specifications as transmitting antenna I is set on the side of the wave-transparent temperature chamber with a wave-transparent window. An absorbing screen is placed around the standard horn antenna, and the side of the wave-transparent temperature chamber with a wave-transparent window passes through the corresponding absorbing screen. A vector network analyzer controlled by an industrial control computer is set outside the absorbing screen. The transmitting antenna I and the standard horn antenna are connected to the corresponding signals of the vector network analyzer. The gain change of transmitting antenna I under different temperature environments is detected by the vector network analyzer.

[0012] High and low temperature characteristics test of S1.3 microwave link:

[0013] The microwave link is placed inside a microwave-transparent temperature chamber, and a vector network analyzer controlled by an industrial computer is set up outside the microwave-transparent temperature chamber. The microwave link is connected to the corresponding signal of the vector network analyzer, and the attenuation of the microwave link under different temperature environments is detected by the vector network analyzer.

[0014] S2, parameter calibration;

[0015] A digital model consistent with the actual test device and transmitting antenna I was established in HFSS software. The reflectivity of the absorbing material used in the device under different temperature environments, the gain change of receiving antenna I under different temperature environments, and the attenuation of the microwave link under different temperature environments were input, as obtained in step S1. The frequency domain finite element method (FEM) was used for simulation calculation. The digital model parameters were subjected to preliminary simulation testing, including mesh preprocessing and iterative calculation. The parameter sensitivity was analyzed and key parameters were confirmed based on the obtained simulation results. After the preliminary simulation was completed, the differences and consistency between the virtual simulation model and the actual test device were compared, and the feasibility analysis of the substitutability of the two in terms of actual effects and fault analysis was conducted. Based on the analysis results, the digital model was repeatedly adjusted and simulation calculations were performed to continuously optimize the model. The axial position offset, axial polarization angle, and frequency point of transmitting antenna I were defined.

[0016] S3 source tracing;

[0017] S3.1 Establish a traceability system:

[0018] The transmitting antenna I is placed inside a wave-transparent temperature chamber. A shielded dark box is installed on the side of the wave-transparent temperature chamber with a wave-transparent window. The shielded dark box includes a box body with one open side. The inner wall of the box is lined with a wave-absorbing material with a reflectivity of less than -40dB. A standard horn antenna is installed inside the shielded dark box, with the open side of the shielded dark box corresponding to the side of the wave-transparent temperature chamber with the wave-transparent window. The standard horn antenna and the transmitting antenna I are connected to the corresponding signals of a vector network analyzer controlled by an industrial control computer. A spatial attenuation standard component is detachably connected to the open side of the shielded dark box. A precision step attenuator is used for the signal connection between the standard horn antenna and the vector network analyzer.

[0019] S3.2 Source Tracing Test:

[0020] Under a temperature condition ranging from -55℃ to 75℃, firstly, without placing the spatial attenuation standard and the precision step attenuator, read the signal received by the standard horn antenna; then, connect the spatial attenuation standard and the precision step attenuator, and read the signal received by the standard horn antenna at this time; the difference between the two signals is the system attenuation; by changing different spatial attenuation standards, adjusting the precision step attenuator, and changing the temperature conditions, the source tracing test of the system across the entire frequency band and temperature range is completed.

[0021] Preferably, the wave-transparent window of the wave-transparent chamber is made of wave-transparent foam, and fiberglass is attached to both sides of the wave-transparent foam.

[0022] Preferably, the microwave-transparent foam is a honeycomb polyurethane foam material or a PMI-type microwave-transparent material.

[0023] Preferably, both the transmitting antenna II and the receiving antenna II are lens antennas, and the lens antennas have two polarization methods: horizontal and vertical polarization.

[0024] Preferably, the transmitting antenna I is a waveguide array antenna with a broadband waveguide subarray. The first sidelobe level of the transmitting antenna I is ≤-20dB; the far sidelobe level is ≤-28dB, and it is divided into two groups according to the frequency coverage, namely the frequency coverage of 1GHz to 18GHz and the frequency coverage of 18GHz to 40GHz. The gain of the frequency coverage of 1GHz to 18GHz is ≥24.5dB and the beamwidth is ≥8°; the gain of the frequency coverage of 18GHz to 40GHz is ≥32dB and the beamwidth is ≥4°.

[0025] Preferably, the waveguide array antenna feeding network covering the frequency band of 1GHz to 18GHz adopts a parallel feeding network, the radiating element adopts a broadband waveguide subarray design, the array size is 8×8 array, and the antenna size is 140mm×140mm×48mm; the antenna radiating element covering the frequency band of 18GHz to 40GHz adopts a matched horn, the upper part is a broadband radiating horn array, and the lower part is a broadband compact multilayer feeding network, the array size is 16×16 array, and the size is 120mm×120mm×35mm.

[0026] Preferably, the walls of the shielded darkroom are covered with a polyurethane pyramidal environmental absorbing material.

[0027] Preferably, the spatial attenuation standard component operates in a frequency band covering 1GHz to 40GHz, and uses EPP rigid polypropylene foam or polyurethane foam flat plate as the spatial attenuation standard component, with attenuation design values ​​of 3dB, 5dB, 10dB, 15dB, 20dB, and 25dB, and a frequency band flatness of ±1.0.

[0028] Preferably, the thickness of the spatial attenuation standard component is ≤100mm. By adjusting the carbon content in the spatial attenuation standard component and utilizing a series of carrier thicknesses, it can be made to have corresponding electromagnetic wave loss and absorption performance. The carbon content varies from 1% to 3%, and the thickness of the spatial attenuation standard component ranges from 5mm to 100mm.

[0029] Preferably, the absorbing screen is a movable screen, and the inner side of the screen is covered with PMI absorbing material.

[0030] By employing the technical solution described above, the present invention has the following beneficial effects:

[0031] The present invention discloses a method for calibrating the microwave attenuation characteristics of a testing device under high and low temperature conditions, which realizes the accurate calibration and traceability of the microwave attenuation characteristics of the testing device under high and low temperature conditions, thereby providing a correction reference for the power test results of high power radiation sources under high and low temperature conditions. Attached Figure Description

[0032] Figure 1A schematic diagram of the structure for testing the high and low temperature reflectivity of the absorbing material used in the device;

[0033] Figure 2 A schematic diagram of the structure for testing the high and low temperature characteristics of receiving antenna I;

[0034] Figure 3 A schematic diagram of the structure for testing the high and low temperature characteristics of a microwave link;

[0035] Figure 4 This is a schematic diagram of the traceability system.

[0036] In the diagram: 1. Industrial computer; 2. Vector network analyzer; 3. Wave-transparent temperature chamber; 4. Wave-absorbing material for the device; 5. Microwave link; 6. Receiving antenna I; 7. Arc-shaped slide rail; 8. Spatial attenuation standard component; 9. Precision step attenuator; 10. Standard horn antenna; 11. Wave-absorbing screen; 12. Shielded dark box. Detailed Implementation

[0037] The present invention can be explained in detail through the following embodiments. The purpose of disclosing the present invention is to protect all technical improvements within the scope of the present invention. In the description of the present invention, it should be understood that if there are terms such as "upper", "lower", "front", "rear", "left", "right" indicating the orientation or positional relationship, they are only corresponding to the drawings of this application for the convenience of describing the present invention, and are not intended to indicate or imply that the device or element referred to must have a specific orientation.

[0038] Combined with appendix Figures 1-4 A calibration method for the high and low temperature microwave attenuation characteristics of a testing device is disclosed. The method involves detecting the power performance of the testing device in the 1GHz–40GHz frequency band and at an ambient temperature of -55℃–75℃ using a transmitting antenna I. The testing device includes a device-grade absorbing material 4, a microwave link 5, and a receiving antenna I 6. The calibration testing system includes an industrial control computer 1, a vector network analyzer 2, and a transparent temperature chamber 3. The transparent temperature chamber 3 provides a temperature environment of -55℃ to 75℃, with a temperature control accuracy ≤ ±2℃, temperature fluctuation ≤ ±0.5℃, and temperature uniformity ≤ 2℃. Simultaneously, humidity is kept constant, and there is no frosting phenomenon that would affect the test. The interior of the transparent temperature chamber 3 is lined with environmental absorbing material to improve the material testing environment; a coated polyurethane pyramidal absorbing material can be selected. A transparent window is provided on one side of the transparent temperature chamber 3. The transmitting antenna I radiates the test signal provided by the vector network analyzer 2, providing a signal source for the receiving antenna I 6. The method includes the following steps:

[0039] S1. Testing of the influence of high and low temperature characteristics of the testing device:

[0040] S1.1 device uses absorbing material 4 for high and low temperature reflectivity testing:

[0041] The device's absorbing material 4 is placed inside a wave-transparent temperature chamber 3. An arc-shaped slide rail 7 is built on the side of the wave-transparent temperature chamber 3 with a wave-transparent window, so that the center of the arc-shaped slide rail 7 falls on the device's absorbing material 4. A transmitting antenna II and a receiving antenna II, which can slide along the arc-shaped slide rail 7, are respectively installed at both ends of the arc-shaped slide rail 7, and the central angle of the arc-shaped slide rail 7 is 60°. An absorbing screen 11 is placed around the outside of the arc-shaped slide rail 7, and the side of the wave-transparent temperature chamber 3 with the wave-transparent window passes through the corresponding absorbing screen 11. A vector network analyzer 2 controlled by an industrial control computer 1 is set outside the absorbing screen 11, and the transmitting antenna II and the receiving antenna II are both connected to the corresponding signal of the vector network analyzer 2. The vector network analyzer 2 detects the reflectivity of the device's absorbing material 4 under different temperature environments. The vector network analyzer 2 tests the attenuation parameter. The industrial control computer 1 controls the vector network analyzer 2 to read the collected data and perform data processing.

[0042] As required, both the transmitting antenna II and the receiving antenna II are lens antennas, and the lens antennas have two polarization methods: horizontal and vertical polarization. This shortens the test radius, thereby reducing the radius of the arc track, reducing the processing difficulty of the arc track, and improving the positional accuracy of the track. At the same time, the lens antenna has higher gain and better directivity, and can quickly form a far field.

[0043] High and low temperature characteristics tests of S1.2 receiving antenna I6 and transmitting antenna I:

[0044] The receiving antenna I6 is placed inside the wave-transparent temperature chamber 3. A standard horn antenna 10 of the same specification as the receiving antenna I6 is set on the side of the wave-transparent temperature chamber 3 with a wave-transparent window. An absorbing screen 11 surrounds the standard horn antenna 10, and the side of the wave-transparent temperature chamber 3 with a wave-transparent window passes through the corresponding absorbing screen 11. A vector network analyzer 2 controlled by an industrial control computer 1 is set on the outside of the absorbing screen 11. The receiving antenna I6 and the standard horn antenna 10 are connected to the corresponding signal of the vector network analyzer 2. The gain change of the receiving antenna I6 under different temperature environments is detected by the vector network analyzer 2.

[0045] The transmitting antenna I is placed inside the wave-transparent temperature chamber 3. A standard horn antenna 10 of the same specification as the transmitting antenna I is set on the side of the wave-transparent temperature chamber 3 with a wave-transparent window. An absorbing screen 11 surrounds the standard horn antenna 10, and the side of the wave-transparent temperature chamber 3 with a wave-transparent window passes through the corresponding absorbing screen 11. A vector network analyzer 2 controlled by an industrial control computer 1 is set on the outside of the absorbing screen 11. The transmitting antenna I and the standard horn antenna 10 are connected to the corresponding signals of the vector network analyzer 2. The gain change of the transmitting antenna I under different temperature environments is detected by the vector network analyzer 2.

[0046] High and low temperature characteristics test of S1.3 microwave link 5:

[0047] The microwave link 5 is placed inside the microwave-transparent temperature chamber 3, and a vector network analyzer 2 controlled by an industrial computer 1 is set outside the microwave-transparent temperature chamber 3. The microwave link 5 is connected to the corresponding signal of the vector network analyzer 2, and the attenuation of the microwave link 5 under different temperature environments is detected by the vector network analyzer 2.

[0048] S2, parameter calibration;

[0049] In HFSS software, a digital model consistent with the actual test device and transmitting antenna I is established. The reflectivity of the absorbing material 4 used in the device under different temperature environments, the gain change of the receiving antenna I 6 under different temperature environments, and the attenuation of the microwave link 5 under different temperature environments are input. The dielectric constant parameter of the absorbing material 4 used in the device under the environment of -55℃ to 75℃ is input to the digital model through the material property settings of HFSS software. After the parameter input is completed, the mesh, boundary conditions, and antenna ports are set accordingly.

[0050] The frequency domain finite element method (FEM) was used for simulation testing to address the challenges of high frequency bands, large model electrical dimensions, high computational load, and high computational resource requirements. During testing, preliminary simulation tests were performed on the digital model parameters, including mesh preprocessing and iterative calculations. Based on the obtained simulation results, parameter sensitivity was analyzed, and key parameters were identified. After completing the preliminary simulation, the differences and consistency between the virtual simulation model and the actual test device were compared, and a feasibility analysis was conducted on the substitutability of the two models in terms of actual effects and fault analysis. Based on the analysis results, the digital model was repeatedly adjusted and simulation calculations were performed to continuously optimize the model, defining the axial position offset, axial polarization angle, and frequency point of the transmitting antenna I.

[0051] S3 source tracing;

[0052] S3.1 Establish a traceability system:

[0053] The transmitting antenna I is placed inside the wave-transparent temperature chamber 3. A shielded dark chamber 12 is set on the side of the wave-transparent temperature chamber 3 with a wave-transparent window. The shielded dark chamber 12 includes a box with one open side. The inner wall of the box is lined with a wave-absorbing material with a reflectivity of less than -40dB. A standard horn antenna 10 is set inside the shielded dark chamber 12, and the open side of the shielded dark chamber 12 corresponds to the side of the wave-transparent temperature chamber 3 with the wave-transparent window. The standard horn antenna 10 and the transmitting antenna I are connected to the corresponding signal of the vector network analyzer 2 controlled by the industrial control computer 1. A spatial attenuation standard component 8 is detachably connected to the open side of the shielded dark chamber 12. A precision step attenuator 9 is connected between the standard horn antenna 10 and the vector network analyzer 2.

[0054] As required, the walls of the shielded dark box 12 are lined with a membrane-coated polyurethane pyramidal absorbing material; the spatial attenuation standard 8 operates in the frequency band of 1GHz to 40GHz, and uses EPP rigid polypropylene foam or polyurethane foam flat plate as the spatial attenuation standard, with attenuation design values ​​of 3dB, 5dB, 10dB, 15dB, 20dB, and 25dB, and a flatness of ±1.0 within the frequency band; the thickness of the spatial attenuation standard 8 is ≤100mm, and by adjusting the carbon content in the spatial attenuation standard and utilizing a series of carrier thicknesses, it has corresponding electromagnetic wave loss and absorption performance, with the carbon content varying from 1% to 3% and the thickness of the spatial attenuation standard ranging from 5mm to 100mm.

[0055] S3.2 Source Tracing Test:

[0056] Under a temperature condition of -55℃ to 75℃, firstly, without placing the spatial attenuation standard component 8 and the precision step attenuator 9, read the signal received by the standard horn antenna 10; then connect the spatial attenuation standard component 8 and the precision step attenuator 9, and read the signal received by the standard horn antenna 10 at this time; the difference between the two signals is the system attenuation; replace different spatial attenuation standard components 8, adjust the precision step attenuator 9, and then change the temperature conditions to complete the source tracing test of the system across the entire frequency band and temperature range;

[0057] In addition, the wave-transparent window of the wave-transparent chamber 3 is made of wave-transparent foam, and fiberglass is attached to both sides of the wave-transparent foam. The wave-transparent foam is a honeycomb polyurethane foam material or a PMI type wave-transparent material, which ensures wave transmission performance while having a good heat preservation effect. The wave-absorbing screen 11 includes a movable screen, and the inner side of the screen is covered with PMI wave-absorbing material to ensure that the return loss is below -30dB, with good wave absorption performance, which can significantly improve the electromagnetic environment.

[0058] The transmitting antenna I is a broadband waveguide subarray antenna. The first sidelobe level of transmitting antenna I is ≤-20dB; the far sidelobe level is ≤-28dB. It is divided into two groups based on frequency coverage: 1GHz~18GHz and 18GHz~40GHz. The gain for the 1GHz~18GHz band is ≥24.5dB, and the beamwidth is ≥8°; the gain for the 18GHz~40GHz band is ≥32dB, and the beamwidth is ≥4°. The feeding network for the 1GHz~18GHz band waveguide array antenna uses a parallel-feed network, and the radiating element is a broadband waveguide subarray design with an 8×8 array size. The antenna dimensions are 140mm×140mm×48mm. The energy distribution is tapered and weighted to achieve a low sidelobe design, with the sidelobe level meeting the required specifications. The antenna radiating element, covering the 18GHz to 40GHz frequency band, uses a matched horn. The upper part is a broadband radiating horn array, and the lower part is a broadband compact multi-layer feed network. The array size is 16×16, with dimensions of 120mm×120mm×35mm, achieving broadband matching. The transmitting antenna I is manufactured using vacuum brazing technology. Microwave devices welded by vacuum brazing have excellent mechanical properties and corrosion resistance. Heating in a vacuum eliminates the oxidation problem of the devices. Vacuum brazing has high precision, uniform heating, and small deformation, which can ensure that the antenna has good stability and low performance fluctuations within the operating temperature range of -50℃ to 75℃.

[0059] Example 1:

[0060] S1. Testing of the influence of high and low temperature characteristics of the testing device:

[0061] S1.1 Place the absorbing material 4 in the center of the wave-transmitting temperature chamber 3, and select the lens antennas, namely the transmitting antenna II and the receiving antenna II; install the transmitting antenna II and the receiving antenna II, which can slide along the arc-shaped slide rail 7, at both ends of the arc-shaped slide rail 7 respectively, and adjust the incident angle of the transmitting antenna II to 20°, and the corresponding receiving angle of the receiving antenna II to 20°; select the temperature points of the wave-transmitting temperature chamber 3 as -50℃, -15℃, 25℃, 55℃, and 75℃, and set the temperature curve; set the frequency range of the vector network analyzer 2 to 12GHz~18GHz, and the frequency step size to 500MHz. The test involved 12 points; the reflectivity of the material at different frequencies was measured at 25℃. Taking 18GHz as an example, the reflectivity at 25℃ was -38dB. Using the reflectivity values ​​at different frequencies at 25℃ as a benchmark, the temperature was varied according to the temperature curve, and the change in reflectivity at the selected temperature points was measured. During this process, data was automatically collected by the industrial control computer 1 and the vector network analyzer 2. The test analysis showed that the changes in material reflectivity at -50℃, -15℃, 55℃, and 75℃ compared to 25℃ were 0.8dB, 0.5dB, 0.2dB, -0.3dB, and -0.7dB, respectively.

[0062] S1.2 Place the receiving antenna I in the wave-transmitting temperature chamber 3; select temperature points of -50℃, -15℃, 25℃, 55℃, and 75℃ for the wave-transmitting temperature chamber 3, and set the temperature curve; set the frequency range of the vector network analyzer 2 to 12GHz~18GHz, with a frequency step of 500MHz, for a total of 12 points; read the transmission parameter test values ​​of the receiving antenna I at different frequency points at 25℃, and normalize them; change the temperature according to the temperature curve, and test the gain change at the selected temperature points. During this process, the industrial control computer 1 automatically collects the data from the vector network analyzer 2; after testing and analysis, the gain change of the receiving antenna I at -50℃, -15℃, 55℃, and 75℃ compared to 25℃ is: 0.1dB, 0.2dB, 0.15dB, and 0.2dB, respectively; the gain change of the transmitting antenna I is: 0.3dB, 0.1dB, 0.2dB, and 0.2dB, respectively.

[0063] The transmitting antenna I was placed in the wave-transparent temperature chamber 3. Temperature points in the temperature chamber 3 were selected as -50℃, -15℃, 25℃, 55℃, and 75℃, and temperature curves were set. The vector network analyzer 2 was set to a frequency range of 12GHz to 18GHz, with a frequency step of 500MHz, for a total of 12 points. The transmission parameter test values ​​of the transmitting antenna I at different frequency points at 25℃ were read and normalized. The temperature was varied according to the temperature curve, and the gain change at the selected temperature points was tested. During this process, the data from the vector network analyzer 2 was automatically collected by the industrial control computer 1. After testing and analysis, the gain changes of the transmitting antenna I at -50℃, -15℃, 55℃, and 75℃ compared to 25℃ were 0.3dB, 0.1dB, 0.2dB, and 0.2dB, respectively.

[0064] S1.3 Place the microwave link 5 in the microwave-transparent temperature chamber 3; select temperature points of -50℃, -15℃, 25℃, 55℃, and 75℃ for the microwave-transparent temperature chamber 3, and set the temperature curve; set the frequency range of the vector network analyzer 2 to 12GHz~18GHz, with a frequency step of 500MHz, for a total of 12 points; test the attenuation of the microwave link 5 at different frequency points at 25℃. Taking 18GHz as an example, the attenuation is 22dB. Using the attenuation value of the microwave link 5 at different frequency points at 25℃ as a benchmark, change the temperature according to the temperature curve and test the change in attenuation at the selected temperature points. During this process, the industrial control computer 1 automatically collects the data from the vector network analyzer 2; after testing and analysis, the changes in attenuation of the microwave link 5 at -50℃, -15℃, 55℃, and 75℃ compared to 25℃ are: 0.3dB, 0.3dB, 0.15dB, and 0.2dB, respectively.

[0065] S2, parameter calibration;

[0066] After the basic parameter tests are completed, the test results at different temperatures are input into the simulation model, and the following simulation conditions are set: axial position offset of transmitting antenna I, axial polarization angle, and frequency points; where the axial position offset of transmitting antenna I is set to 0mm, 0.1mm, 0.26mm, 1mm, 5mm, and 10mm; the axial polarization angle is set to 0°, 0.1°, 1°, 2°, and 3°; the frequency range is set to 12GHz to 18GHz, with a frequency step of 500MHz, for a total of 12 points;

[0067] Simulation outputs yielded attenuation values ​​under various conditions: -50℃, -15℃, 25℃, 55℃, and 75℃. Analysis showed that the influence of axial polarization angle within 0.1° on attenuation was negligible; the influence of positional offset on attenuation within 0.26mm was also negligible. Therefore, the axial positional offset of transmitting antenna I was set to 0mm, with an accuracy control within ±0.26mm; the axial polarization angle was set to 0°, with an accuracy control within ±0.1°, as calibration conditions. Under these conditions, the test setup was calibrated, and the attenuation of microwave link 5, the gain of receiving antenna I, the gain of transmitting antenna I, and their temperature variations were corrected.

[0068] The attenuation of the test device was measured at -50℃, -15℃, 25℃, 55℃, and 75℃, with a frequency range of 12GHz to 18GHz and a frequency step of 500MHz. Taking 18GHz as an example, the attenuation values ​​at different temperature points were 44.2dB, 44.5dB, 45.0dB, 45.3dB, and 45.6dB, respectively.

[0069] S3 source tracing;

[0070] The test is complete. To verify the accuracy of the test system, measurements were taken, and the traceability process is as follows:

[0071] Complete the hardware connection according to the traceability system. Set the frequency range to 12GHz~18GHz, the frequency step to 500MHz, and initially set the temperature of the wave transmission chamber 3 to 25℃. Normalize the values ​​measured by the vector network analyzer 2 at this temperature. Then, sequentially insert the spatial attenuation standard components 8 with attenuation values ​​of 3dB, 5dB, 10dB, 15dB, 20dB, and 25dB. For attenuations above 25dB, simultaneously connect the precision step attenuator 9 and adjust its attenuation. Set the attenuation values ​​of the precision step attenuator 9 to 10dB and 25dB respectively. At this point, the overall... The attenuation can reach 35dB and 50dB. Test data at a set frequency point is collected from the vector network analyzer 2, and the gain change of the transmitting antenna I is used to correct the test data. The corrected data is the final test value. Taking 18GHz as an example, the final test values ​​are: 3.2dB, 5.3dB, 9.8dB, 15.8dB, 20.4dB, 24.7dB, 34.5dB, and 50.6dB. Then, the temperature of the transparent temperature chamber 3 is set to -50℃, -15℃, 55℃, and 75℃ in sequence. The above steps are repeated to measure the attenuation value at the corresponding temperature.

[0072] The space attenuation standard component 8 was tested by a metrology institution, which provided test data on the attenuation at room temperature. The test results of the above system traceability were compared with the test data provided by the metrology institution to evaluate the performance of the test system. According to the comparison, taking 18GHz as an example, the difference between the attenuation of the space attenuation standard component 8 and the test results of the metrology institution was within 1.2dB, indicating that the system values ​​are reliable.

[0073] The parts of this invention not described in detail are prior art. It will be apparent to those skilled in the art that this invention is not limited to the details of the above exemplary embodiments, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be regarded as exemplary and non-limiting in all respects, and are intended to encompass all changes falling within the meaning and scope of equivalents within this invention.

Claims

1. A method for calibrating the high and low temperature microwave attenuation characteristics of a test device, wherein the power performance of the test device in the 1GHz~40GHz frequency band and the ambient temperature of -55℃~75℃ is detected by transmitting antenna I, the test device includes device absorbing material (4), microwave link (5) and receiving antenna I (6); the wave-transparent temperature chamber (3) calibration test system includes industrial control computer (1), vector network analyzer (2) and wave-transparent temperature chamber (3); the wave-transparent temperature chamber (3) provides a temperature environment of -55℃~75℃, the temperature control accuracy of the wave-transparent temperature chamber (3) is ≤±2℃, the temperature fluctuation is ≤±0.5℃, the temperature uniformity is ≤2℃, the inside of the wave-transparent temperature chamber (3) is lined with environmental absorbing material to improve the material testing environment, and a wave-transparent window is provided on one side of the wave-transparent temperature chamber (3); its characteristics are: Includes the following steps: S1. Testing of the influence of high and low temperature characteristics of the testing device: High and low temperature reflectivity test of absorbing material (4) for device S1.1: Place the device's absorbing material (4) inside the wave-transparent temperature chamber (3). Build an arc-shaped slide rail (7) on one side of the wave-transparent temperature chamber (3) with a wave-transparent window, so that the center of the arc-shaped slide rail (7) falls on the device's absorbing material (4). Install transmitting antenna II and receiving antenna II, which can slide along the arc-shaped slide rail (7), respectively, at both ends of the arc-shaped slide rail (7). The central angle of the arc-shaped slide rail (7) is 60°. Surround the arc-shaped slide rail (7) with an absorbing screen (11). Make the side of the wave-transparent temperature chamber (3) with a wave-transparent window pass through the corresponding absorbing screen (11). Set up a vector network analyzer (2) controlled by an industrial control computer (1) outside the absorbing screen (11). Connect both transmitting antenna II and receiving antenna II to the corresponding signal of the vector network analyzer (2). Detect the reflectivity of the device's absorbing material (4) under different temperature environments using the vector network analyzer (2). S1.2 High and low temperature characteristics test of receiving antenna I (6) and transmitting antenna I: The receiving antenna I (6) is placed inside the wave-transparent temperature chamber (3). A standard horn antenna (10) of the same specification as the receiving antenna I (6) is set on one side of the wave-transparent temperature chamber (3) with a wave-transparent window. An absorbing screen (11) surrounds the standard horn antenna (10) and the side of the wave-transparent temperature chamber (3) with a wave-transparent window passes through the corresponding absorbing screen (11). A vector network analyzer (2) controlled by an industrial computer (1) is set on the outside of the absorbing screen (11). The receiving antenna I (6) and the standard horn antenna (10) are connected to the corresponding signal of the vector network analyzer (2). The gain change of the receiving antenna I (6) under different temperature environments is detected by the vector network analyzer (2). Place the transmitting antenna I inside the wave-transparent temperature chamber (3). Set a standard horn antenna (10) of the same specification as the transmitting antenna I on one side of the wave-transparent temperature chamber (3) with a wave-transparent window. Surround the standard horn antenna (10) with a wave-absorbing screen (11) around it. Make the side of the wave-transparent temperature chamber (3) with a wave-transparent window pass through the corresponding wave-absorbing screen (11). Set a vector network analyzer (2) controlled by an industrial control computer (1) on the outside of the wave-absorbing screen (11). Connect the transmitting antenna I and the standard horn antenna (10) to the corresponding signal of the vector network analyzer (2). Detect the gain change of the transmitting antenna I under different temperature environments through the vector network analyzer (2). High and low temperature characteristics test of S1.3 microwave link (5): The microwave link (5) is placed inside the microwave-transparent temperature chamber (3), and a vector network analyzer (2) controlled by an industrial computer (1) is set outside the microwave-transparent temperature chamber (3) so that the microwave link (5) is connected to the corresponding signal of the vector network analyzer (2). The attenuation of the microwave link (5) under different temperature environments is detected by the vector network analyzer (2). S2, parameter calibration; In HFSS software, a digital model consistent with the actual test device and transmitting antenna I is established. The reflectivity of the device absorbing material (4) obtained in step S1 under different temperature environments, the gain change of receiving antenna I (6) under different temperature environments, and the attenuation of microwave link (5) under different temperature environments are input. The frequency domain finite element method (FEM) is used for simulation calculation. The parameters of the digital model are subjected to preliminary simulation test including mesh preprocessing and iterative calculation. The parameter sensitivity is analyzed and key parameters are confirmed based on the obtained simulation results. After completing the initial simulation, the differences and similarities between the virtual simulation model and the actual test device are compared, and a feasibility analysis is conducted on the actual effects and fault analysis of the two. Based on the analysis results, the digital model is repeatedly adjusted and simulation calculations are performed to continuously optimize the model and define the axial position offset, axial polarization angle, and frequency point of the transmitting antenna I. S3 source tracing; S3.1 Establish a traceability system: The transmitting antenna I is placed inside the wave-transparent temperature box (3). A shielded dark box (12) is set on the side of the wave-transparent temperature box (3) with a wave-transparent window. The shielded dark box (12) includes a box with one open side. The inner wall of the box is covered with an environmental absorbing material with a reflectivity of less than -40dB. A standard horn antenna (10) is set inside the shielded dark box (12). The open side of the shielded dark box (12) is aligned with the side of the wave-transparent temperature box (3) with a wave-transparent window. The standard horn antenna (10) and the transmitting antenna I are connected to the corresponding signal of the vector network analyzer (2) controlled by the industrial control computer (1). A spatial attenuation standard component (8) is detachably connected to the open side of the shielded dark box (12). A precision step attenuator (9) is connected between the standard horn antenna (10) and the vector network analyzer (2). S3.2 Source Tracing Test: Under a temperature condition of -55℃ to 75℃, firstly, without placing the spatial attenuation standard (8) and the precision step attenuator (9), read the signal received by the standard horn antenna (10); then connect the spatial attenuation standard (8) and the precision step attenuator (9), and read the signal received by the standard horn antenna (10) at this time; the difference between the two signals is the system attenuation; replace different spatial attenuation standard (8), adjust the precision step attenuator (9), and then change the temperature conditions to complete the traceability test of the system in the full frequency band and full temperature range.

2. The high and low temperature microwave attenuation characteristic calibration method of the test device as described in claim 1, characterized in that: The transparent window of the transparent temperature chamber (3) is made of transparent foam, and fiberglass is attached to both sides of the transparent foam.

3. The high and low temperature microwave attenuation characteristic calibration method of the test device as described in claim 2, characterized in that: The microwave-transparent foam is a honeycomb polyurethane foam material or a PMI-type microwave-transparent material.

4. The high and low temperature microwave attenuation characteristic calibration method of the test device as described in claim 1, characterized in that: Both the transmitting antenna II and the receiving antenna II are lens antennas, and the lens antennas have two polarization methods: horizontal and vertical polarization.

5. The high and low temperature microwave attenuation characteristic calibration method of the test device as described in claim 1, characterized in that: The transmitting antenna I is a waveguide array antenna with a broadband waveguide subarray. The first sidelobe level of transmitting antenna I is ≤-20dB; the far sidelobe level is ≤-28dB. It is divided into two groups according to frequency coverage: one for 1GHz to 18GHz and the other for 18GHz to 40GHz. The gain for the frequency coverage of 1GHz to 18GHz is ≥24.5dB and the beamwidth is ≥8°. The gain for the frequency coverage of 18GHz to 40GHz is ≥32dB and the beamwidth is ≥4°.

6. The high and low temperature microwave attenuation characteristic calibration method of the test device as described in claim 5, characterized in that: The waveguide array antenna covering the frequency band of 1GHz to 18GHz adopts a parallel feed network, and the radiating element adopts a broadband waveguide subarray design. The array size is 8×8, and the antenna size is 140mm×140mm×48mm. The antenna radiating element covering the frequency band of 18GHz to 40GHz adopts a matched horn. The upper part is a broadband radiating horn array, and the lower part is a broadband compact multilayer feed network. The array size is 16×16, and the size is 120mm×120mm×35mm.

7. The high and low temperature microwave attenuation characteristic calibration method of the test device as described in claim 1, characterized in that: The environmental absorbing material is a coated polyurethane pyramidal absorbing material.

8. The high and low temperature microwave attenuation characteristic calibration method of the test device as described in claim 1, characterized in that: The spatial attenuation standard component (8) operates in a frequency band of 1GHz to 40GHz. It uses EPP rigid polypropylene foam or polyurethane foam flat plate as the spatial attenuation standard component, with attenuation design values ​​of 3dB, 5dB, 10dB, 15dB, 20dB, and 25dB, and a frequency band flatness of ±1.

0.

9. The high and low temperature microwave attenuation characteristic calibration method of the test device as described in claim 1, characterized in that: The thickness of the space attenuation standard (8) is ≤100mm. By adjusting the carbon content in the space attenuation standard and using a series of carrier thicknesses, it can have corresponding electromagnetic wave loss and absorption performance. The carbon content ranges from 1% to 3%, and the thickness of the space attenuation standard ranges from 5mm to 100mm.

10. The high and low temperature microwave attenuation characteristic calibration method of the test device as described in claim 1, characterized in that: The microwave absorbing screen (11) is a movable screen, and PMI microwave absorbing material is laid on the inner side of the screen.

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