Relative calibration method suitable for RCS test in high-temperature environment
By testing the frequency domain response data of conventional metal scale bodies under high temperature environment, the fitting curve is constructed, and the RCS value of the target to be tested is inverted, which solves the problem of softening, deformation or oxidation of standard metal scale bodies at high temperatures, and achieves the accuracy and economicality of RCS test at high temperatures.
Patent Information
- Application Number
- CN202510222155.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-02-27
- Publication Date
- 2025-05-30
AI Technical Summary
When conducting radar scattering cross-section (RCS) testing in high temperature environments, standard metal scale bodies may experience softening, deformation or oxidation at high temperatures, resulting in increased testing errors and costs.
RCS test is performed using conventional metal scale bodies. By testing its frequency domain response data at different temperatures, a fitting curve is constructed, and the RCS value of the target to be tested at high temperature is inverted.
It realizes that the RCS value of the target to be tested is accurately obtained at high temperature without relying on high-temperature resistant metal materials, reducing the test error and material cost.
Smart Images
Figure CN120065151A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of radar cross section testing, and particularly relates to a relative calibration method applicable to RCS testing in high-temperature environments. Background Art
[0002] The stealth performance of major equipment has been highly regarded by various countries, and the size of the radar cross section (RCS) can, to a certain extent, reflect the level of the target's stealth performance. In fields such as aerospace, high-temperature environments often cause significant changes in the electromagnetic characteristics of materials or components compared to normal temperature environments. Therefore, placing the target to be measured in a high-temperature environment for testing can more accurately evaluate its high-temperature RCS characteristics.
[0003] Currently, when conducting RCS testing, it is necessary to calibrate various parameters of the testing system (including vector network analyzers, antennas, etc.), such as S 21 and other parameters. The calibration methods include the absolute measurement method and the relative measurement method. In the absolute measurement method, accurate parameters and error values of the system need to be obtained. However, the electromagnetic parameters of the testing system often exhibit time-varying characteristics and are difficult to accurately measure and analyze. Therefore, the relative calibration method is often used in actual testing work. The relative calibration method is based on the accurate electromagnetic scattering characteristic data of the calibration body RCS, and calculates the RCS value of the target to be measured through the ratio of the electromagnetic power or voltage measured for the calibration body and the target to be measured. In this process, the test errors that have the same influence on the standard calibration body and the target to be measured can be canceled out (Yao Zhaoning. Measurement and Analysis of Radar RCS Target Characteristics [D]. Nanjing University of Science and Technology, 2003.).
[0004] In the relative calibration method for RCS testing, the standard calibration body used is generally made of metal materials. Most of the melting points of common metal materials are relatively low. Especially for metal materials with good ductility, easy to process, light and easy to fix and clamp, such as the melting point of copper is 1083.4 °C, and the melting point of aluminum is 660 °C; before reaching the melting point, the standard metal calibration body will also show softening deformation, high-temperature oxidation, etc., resulting in large test errors. Therefore, when using the relative calibration method to conduct RCS testing in a high-temperature environment, only metal calibration bodies made of high-temperature-resistant metal materials can be selected for testing. However, materials with better heat resistance are often expensive. At the same time, high-temperature-resistant metal materials are difficult to process, and it is not easy to make their surfaces flat enough to meet the RCS testing conditions.
[0005] How to reasonably design the testing method according to the requirements of high-temperature RCS testing, so that the high-temperature RCS testing does not depend on high-temperature-resistant metal calibration bodies, is of great significance for high-temperature RCS testing. Summary of the Invention
[0006] In view of the problems existing in the background technology, the purpose of the present invention is to provide a relative calibration method suitable for RCS testing in a high temperature environment. The method uses a conventional metal calibration body for RCS testing, tests the frequency domain response data of the calibration body at different temperatures, constructs a fitting curve based on the temperature and the corresponding frequency domain response data, and obtains the RCS value of the target to be tested at high temperature by inverting the fitting curve.
[0007] To achieve the above object, the technical solution of the present invention is as follows:
[0008] A relative calibration method suitable for RCS testing in a high temperature environment comprises the following steps:
[0009] Step 1. Connect the RCS test system and perform debugging and calibration;
[0010] Step 2. Test the standard calibration body at several different temperatures and record the temperature T i The frequency domain response data of i is the i-th measured temperature;
[0011] Step 3. Construct a coordinate system with the test temperature as the horizontal axis and the frequency domain response data as the vertical axis. Use the logarithmic function fitting method to fit the data obtained in step 2 to obtain a fitting curve in the coordinate system. t is temperature;
[0012] Step 4. Set the test environment to the test required temperature T, test the target to be tested, and record its frequency domain response data as
[0013] Step 5. Fitting curve of the frequency domain response of the standard calibration body with temperature Inversely calculate the frequency domain response data of the standard calibration body at the test temperature T
[0014] Step 6. Calculate the RCS value RCSobject of the target under test at temperature T. The calculation formula is:
[0015]
[0016] Among them, RCSsphere is the RCS value of the standard calibration body.
[0017] Further, in step 1, the RCS test system includes a vector network analyzer 1, a computer 2, a transceiver antenna 3, a motor control module 4 and a turntable 5;
[0018] Among them, the vector network analyzer 1 establishes communication with the computer 2, and its ports are connected to the transceiver antenna 3; the center of the radiation aperture surface of the transceiver antenna 3 is aligned with the center of the target under test 6 or the standard calibration body; the turntable 5 is placed horizontally, and the target under test 6 or the standard calibration body is placed thereon; the turntable can rotate at a constant speed; the computer 2 is connected to and controls the vector network analyzer 1 to realize functions such as electromagnetic data testing, reading, and storage.
[0019] Further, the RCS test system further includes a motor control module 4. One end of the motor control module 4 is connected to the computer 2, and the other end is connected to the turntable 5; the motor control module 4 sends relevant control signals under the drive of the computer 2 to control the turntable 5 to rotate at a constant speed.
[0020] Further, the standard calibration body is a metal ball, a metal plate, a metal cylinder, etc.
[0021] Further, the setting rule of the test temperature in step 2 is: from room temperature to the highest temperature that the selected standard calibration body can withstand, several test temperatures are set according to requirements to achieve a better fitting effect.
[0022] Further, the logarithmic function fitting method uses the logarithmic function as the fitting model and solves the model parameters by the least squares method.
[0023] The mechanism of the present invention is as follows:
[0024] The present invention innovatively summarizes the law of the electromagnetic scattering characteristics of the standard calibration body changing with temperature into a specific mathematical function form, and uses the logarithmic function fitting method to construct a quantitative relationship model between the electromagnetic scattering characteristics and temperature of the standard calibration body. This model uses the known electromagnetic scattering characteristics of the standard calibration body in the lower temperature range as basic data, can accurately predict its electromagnetic scattering characteristics in a high-temperature environment, and further combines the relative calibration technology in RCS testing to realize the effective testing of RCS under high-temperature conditions. The present invention avoids problems such as softening, deformation, or oxidation of the standard calibration body that may be caused by high temperature during the traditional high-temperature testing process, thereby ensuring the accurate acquisition of RCS data at high temperature.
[0025] In summary, due to the adoption of the above technical solutions, the beneficial effects of the present invention are:
[0026] The present invention proposes a relative calibration test method based on logarithmic function fitting in RCS testing under high-temperature environments. By establishing the corresponding relationship between different temperatures and the frequency response of the standard calibration body, a fitting function for the scattering characteristics of the standard calibration body varying with temperature is obtained through fitting, and the frequency response of the standard calibration body at the temperature required for testing is calculated. Combining with the frequency response of the target to be measured at the temperature required for testing, the RCS value of the target to be measured is analyzed. The method of the present invention can accurately obtain the RCS value of the target to be measured at the temperature required for testing even under the condition that the temperature resistance of the standard calibration body is limited, reduces the test error caused by the oxidation and deformation of the standard calibration body at high temperatures, and also eliminates the expensive material cost and processing cost brought by using high-temperature-resistant metal materials as the standard calibration body. Brief Description of the Drawings
[0027] Figure 1 It is a schematic flow chart of the relative calibration method applicable to RCS testing in high-temperature environments according to the present invention.
[0028] Figure 2 It is a schematic structural diagram of the RCS testing system according to the present invention.
[0029] Figure 3 It is a fitting curve of the stainless steel (304) hollow metal conductor calibration sphere in Embodiment 1 of the present invention.
[0030] Figure 4 It is a fitting curve of the metal aluminum plate standard calibration body in Embodiment 2 of the present invention.
[0031] Reference numerals: 1 is a vector network analyzer, 2 is a computer, 3 is a transceiver antenna, 4 is a motor control module, and 5 is a turntable. Detailed Embodiments
[0032] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the embodiments and the drawings.
[0033] Under normal circumstances, when using the relative calibration method for RCS testing, it is necessary to collect the electromagnetic scattering test data of the standard calibration body and the electromagnetic scattering test data of the target to be measured; under high-temperature conditions, the target to be measured generally undergoes special design to ensure its normal use, while the melting point of the standard calibration body is often lower than the temperature required for testing, or it will undergo softening deformation, high-temperature oxidation, etc. at the temperature required for testing, thus affecting the test results.
[0034] Therefore, it is necessary to use materials with higher melting points to process the standard calibration body. However, metal materials with higher melting points are costly, and there may be problems such as poor ductility, making them difficult to process, or large density, making them inconvenient to hold and fix for testing. Or design a testing method so that the standard calibration body can complete the test without being heated to the required test temperature. The present invention designs a relative calibration testing method based on logarithmic function fitting in RCS testing under high-temperature environments, which solves the above problems.
[0035] Example 1
[0036] A relative calibration method applicable to RCS testing under high-temperature environments. The process of this method is as Figure 1 shown and includes the following steps:
[0037] Step 1. Connect the RCS testing system and perform debugging and calibration;
[0038] The structural schematic diagram of the testing system device is as Figure 2 shown and includes a vector network analyzer 1, a computer 2, a transceiver antenna 3, a motor control module 4, and a turntable 5;
[0039] Among them, the vector network analyzer 1 is connected to the computer 2 through a serial data transmission line and is simultaneously connected to the transceiver antenna 3 through a radio frequency cable; the center of the radiation aperture surface of the transceiver antenna 3 is aligned with the center of the target under test 6; the turntable 5 is placed horizontally, and the target under test 6 is placed thereon; the motor control module 4 is connected to the computer 2 through a serial data transmission line and is simultaneously connected to the turntable 5 through a serial data connection line, and controls the turntable 5 to rotate at a constant speed under the drive of the control signal of the computer 2; the computer 2 is connected to and controls the vector network analyzer 1 to realize functions such as electromagnetic data testing, reading, and storage, and is simultaneously connected to the motor control module 4 to send relevant control signals;
[0040] Step 2. Use a stainless steel (304) hollow metal conductor sphere with a diameter of 200 mm as the standard calibration body, and test the standard calibration body at 100 °C, 200 °C, 300 °C, 400 °C, 500 °C, 600 °C, 700 °C, and 800 °C, and record the corresponding frequency-domain response data at each temperature. The logarithmic amplitude values (8 GHz) are respectively: -2.02 dB, -1.73 dB, -1.89 dB, -1.87 dB, -1.91 dB, -2.05 dB, -1.85 dB, -1.80 dB;
[0041] Step 3. Take the test temperature as the abscissa and the frequency-domain response data as the ordinate to construct a two-dimensional rectangular coordinate system, and use the logarithmic function fitting method to fit the data obtained in Step 2 to obtain a fitting curve in the coordinate system as Figure 3 shown;
[0042] Step 4. The target to be measured is a superalloy plate (GH3039, with dimensions of 500 mm × 100 mm × 4 mm). The test conditions are: frequency of 8 GHz, temperature of 1000 °C, and the 0° facing direction (i.e., the direction with the maximum RCS value). Record its frequency-domain response as 12.50 dB;
[0043] Step 5. Based on Figure 3 the fitting curve shown back-calculate the frequency-domain response data at the test temperature T, and calculate its logarithmic amplitude value as -1.88 dB;
[0044] Step 6. Calculate the RCS value RCSobject of the target to be measured at temperature T. The calculation formula is:
[0045]
[0046] where RCSsphere is the RCS value of the standard calibration body.
[0047] The theoretical RCS value of a stainless steel (304) hollow metal conductor sphere is -15.0285 dBsm. Based on the method described in the present invention, at the test required temperature (1000 °C), the RCS test value of the superalloy plate to be measured is 13.72 dBsm, and its simulation calculation value is 13.49 dBsm. The test error ≤ 0.5 dB, and the test results are in good agreement with the simulation calculation results.
[0048] Example 2
[0049] A relative calibration method applicable to RCS testing in high-temperature environments includes the following steps:
[0050] Step 1. Connect the RCS test system and perform debugging and calibration; the structural schematic diagram of the test system device is as Figure 2 shown;
[0051] Step 2. Use a metal aluminum plate (with dimensions of 500 mm × 100 mm × 4 mm) as the standard calibration body, and test the standard calibration body at 100 °C, 200 °C, 300 °C, 400 °C, 500 °C, 600 °C, 700 °C, and 800 °C. Record the corresponding frequency-domain response data at each temperature, and its logarithmic amplitude values (8 GHz) are respectively: 10.45 dB, 10.45 dB, 10.44 dB, 10.44 dB, 10.39 dB, 10.35 dB, 10.31 dB, 10.28 dB;
[0052] Step 3. Take the test temperature as the abscissa and the frequency-domain response data as the ordinate to construct a two-dimensional rectangular coordinate system, and use the logarithmic function fitting method to fit the data obtained in Step 2, and obtain the fitting curve in the coordinate system asFigure 4 as shown
[0053] Step 4. The target to be measured is a superalloy plate (GH3039, with dimensions of 300 mm × 100 mm × 4 mm). The test conditions are: frequency of 8 GHz, temperature of 1000 °C, 0° facing direction (i.e., the direction with the maximum RCS value), and record its frequency-domain response of 7.93 dB;
[0054] Step 5. Based on Figure 4 the fitting curve as shown back-calculate the frequency-domain response data at the test temperature T, and calculate its logarithmic amplitude value to be 10.31 dB;
[0055] Step 6. Calculate the RCS value RCSobject of the target to be measured at temperature T. The calculation formula is:
[0056]
[0057] where RCSsphere is the RCS value of the standard calibration body.
[0058] For the standard calibration body metal aluminum plate with dimensions of 500 mm × 100 mm × 4 mm at a facing angle of 0° (0°) at a frequency of 8 GHz, the theoretical RCS value is 13.4909 dBsm. Based on the method described in the present invention, at the test required temperature (1000 °C), the RCS test value of the target superalloy plate to be measured is 8.73 dBsm, and its simulation calculation value is 9.05 dBsm. The test error ≤ 0.5 dB, and the test results are in good agreement with the simulation calculation results.
[0059] The above is only the specific implementation manner of the present invention. Any feature disclosed in this specification, unless specifically described, can be replaced by other equivalent or similar-purpose alternative features; all the features disclosed, or all the steps in any method or process, except for mutually exclusive features and / or steps, can be combined in any way.
Claims
1. A relative calibration method suitable for RCS testing in a high temperature environment, characterized in that: The following steps are involved: Step 1. Connect the RCS test system and perform debugging and calibration; Step 2. Test the standard calibration body at several different temperatures and record the temperature T at each temperature. i The frequency domain response data of i is the i-th measured temperature; Step 3. Construct a coordinate system with the test temperature as the horizontal axis and the frequency domain response data as the vertical axis. Use the logarithmic function fitting method to fit the data obtained in step 2 to obtain a fitting curve in the coordinate system. t is temperature; Step 4. Set the test environment to the test required temperature T, test the target to be tested, and record its frequency domain response data as Step 5. Fitting curve of the frequency domain response of the standard calibration body with temperature Inversely calculate the frequency domain response data of the standard calibration body at the test temperature T Step 6. Calculate the RCS value RCSobject of the target under test at temperature T. The calculation formula is: Among them, RCSsphere is the RCS value of the standard calibration body.
2. The relative calibration method for RCS testing in a high temperature environment as claimed in claim 1, characterized in that: In step 1, the RCS test system includes a vector network analyzer, a computer, a transceiver antenna, and a turntable; The vector network analyzer establishes communication with a computer, and its port is connected to a transceiver antenna; the center of the radiation aperture of the transceiver antenna is aligned with the center of the target to be measured or the standard calibration body; the turntable is placed horizontally, and the target to be measured or the standard calibration body is placed on it; the turntable can rotate at a constant speed; the computer is connected to and controls the vector network analyzer to realize electromagnetic data testing, reading and storage functions.
3. The relative calibration method for RCS testing in a high temperature environment as claimed in claim 2, characterized in that: The RCS test system also includes a motor control module, one end of which is connected to the computer and the other end is connected to the turntable; the motor control module sends relevant control signals under the drive of the computer to control the turntable to rotate at a uniform speed.
4. The relative calibration method for RCS testing in a high temperature environment as claimed in claim 1, characterized in that: The standard calibration body is a metal ball, a metal plate or a metal cylinder.
5. The relative calibration method for RCS testing in a high temperature environment as claimed in claim 1, characterized in that: The setting rule of the test temperature in step 2 is: from room temperature to the highest tolerable temperature of the selected standard calibration body, and several test temperatures are set according to needs.
6. The relative calibration method for RCS testing in a high temperature environment as claimed in claim 1, characterized in that: The logarithmic function fitting method uses the logarithmic function as the fitting model and solves the model parameters by the least squares method.