Blackbody bistatic scattering energy measurement method and device

Abstract

The invention provides a black body bistatic scattering energy measuring method and device. The device mainly comprises a vector network analyzer, a receiving and transmitting antenna, a fixed support, a rotary table and a sliding rail. The echo amplitudes of the black body at different angles are comprehensively measured by adopting a cooperative rotation mode of the rotary table and the slide rail; namely, the method can accurately measure the scattering energy of the black body at different angles, further obtains the scattering rate of the black body, comprehensively obtains the scattering characteristics of the black body in different directions, and achieves the high-precision value traceability of the brightness temperature of the black body. In addition, the measuring device has expansibility and universality, and can meet the measuring requirements of black bodies of various specifications.

Description

Technical Field

[0001] The present invention belongs to the technical field of precision measurement and calibration, and in particular relates to a method and device for measuring blackbody bistatic scattering energy. Background Art

[0002] High-sensitivity broadband radiometers are the primary payloads of microwave remote sensing, and microwave calibration blackbodies are core components of microwave radiometer systems. In long-term quantitative remote sensing applications, such as spaceborne microwave radiometers, high-performance standard blackbodies can effectively improve radiometer calibration accuracy and are a core research task for large-scale detection systems. Accurately measuring the emissivity of microwave calibration blackbodies is crucial to radiometer calibration accuracy.

[0003] For a blackbody with any shape and structure, the emissivity measurement process not only includes the reflected energy in the main direction, but also the lateral scattering must be considered. Therefore, the scattered energy needs to be corrected. Summary of the Invention

[0004] To solve the above problems, the present invention provides a blackbody bistatic scattered energy measurement method and device, which can accurately measure the scattering factor of the blackbody and comprehensively obtain the scattering characteristics of the blackbody in different directions.

[0005] A blackbody bistatic scattered energy measurement device includes a vector network analyzer, a transceiver antenna, a fixed bracket, a rotating turntable, and a slide rail. The fixed bracket is divided into a base and a turntable bracket. The rotating turntable is mounted on the base via the turntable bracket. A microwave calibration blackbody or metal ball is mounted on the rotating turntable. The slide rail is mounted on the base. A transmitting antenna and a receiving antenna are both mounted on the slide rail. The transmitting antenna is fixed on the slide rail and is located directly below the microwave calibration blackbody or metal ball. The receiving antenna can be moved to different positions on the slide rail. The vector network analyzer is connected to the transmitting antenna and the receiving antenna respectively.

[0006] The transmitting antenna is used to radiate the radio frequency signal output by the vector network analyzer to the microwave calibration blackbody or metal sphere; the receiving antenna is used to receive the electromagnetic echo signal scattered back from the microwave calibration blackbody or metal sphere and forward the electromagnetic echo signal to the vector network analyzer.

[0007] Furthermore, the shape of the slide rail is a quarter arc.

[0008] Furthermore, the transmitting antenna is always facing a rotating turntable on which a microwave calibration blackbody or a metal ball is fixed, and the rotating turntable can rotate 360 ​​degrees with the radial direction of the transmitting antenna as the rotation axis;

[0009] The center of the slide rail coincides with the position of the microwave calibration black body or the metal ball, and the receiving antenna is directly opposite to the microwave calibration black body or the metal ball on the slide rail.

[0010] Furthermore, the measurement location is selected in a microwave darkroom.

[0011] A method for measuring blackbody bistatic scattered energy comprises the following steps:

[0012] Step 1: Perform error correction on the vector network analyzer;

[0013] Step 2: Use a vector network analyzer with error correction to measure and accumulate the scattered energy of the metal ball at different angles;

[0014] Step 3: Use the error-corrected vector network analyzer to measure and accumulate the scattered energy of the microwave calibration blackbody at different angles;

[0015] Step 4: Obtain the scattering rate of the microwave calibration blackbody according to the scattering energy of the metal ball at different angles and the scattering energy of the microwave calibration blackbody at different angles.

[0016] Furthermore, in step 2, the method for measuring and accumulating the scattered energy of the metal ball at different angles using the error-corrected vector network analyzer is as follows:

[0017] A metal ball is mounted on a rotating turntable, the rotating turntable on which the metal ball is mounted is fixed, and the receiving antenna is continuously moved according to a set step length, and the moving angle range of the receiving antenna on the slide rail is 0° to 90°. Whenever the receiving antenna moves a set angle j along the slide rail, the electromagnetic echo signal of the metal ball at the set angle j within a set time period is collected by the receiving antenna. The electromagnetic echo signal at the set angle j is accumulated by the error-corrected vector network analyzer to obtain the scattering energy e of the metal ball at the set angle j. ball (j).

[0018] Furthermore, in step 3, the method for measuring and accumulating the scattered energy of the microwave calibration blackbody at different angles using the error-corrected vector network analyzer is as follows:

[0019] The measurement location is selected in a microwave darkroom, and the microwave calibration blackbody is installed on a rotating turntable. The rotating turntable drives the microwave calibration blackbody to rotate with the radial direction of the transmitting antenna as the rotation axis. Every time it rotates a set angle i, the receiving antenna moves along the slide rail to set an angle j. The electromagnetic echo signal of the microwave calibration blackbody at the angle combination (i, j) within a set time period is collected by the receiving antenna. The electromagnetic echo signal at the angle combination (i, j) is accumulated by the error-corrected vector network analyzer to obtain the scattering energy e of the microwave calibration blackbody at the angle combination (i, j). scatter(i, j); and so on, the scattered energy of the microwave calibration blackbody at different angle combinations is measured step by step until the microwave calibration blackbody completes a 360° rotation and the receiving antenna completes a 90° movement at each degree, and the measurement process is completed.

[0020] Furthermore, the transmitting antenna irradiates the microwave calibration blackbody with a fixed power, wherein the power of the transmitting antenna needs to be adjusted according to the characteristics of the microwave calibration blackbody to ensure that the microwave calibration blackbody can fully absorb and scatter electromagnetic energy.

[0021] Furthermore, in step 4, the calculation method of the scattering rate of the microwave calibration blackbody is as follows:

[0022]

[0023] Where η is the scattering rate of the microwave calibration blackbody, i is the rotation angle of the rotating turntable, and the value range of i is 0° to 360°, j is the moving angle of the receiving antenna on the slide rail, and the value range of j is 0° to 90°, e scatter (i, j) is the scattered energy of the microwave calibration blackbody when the rotation angle of the rotating turntable is i and the moving angle of the receiving antenna on the slide is j, e ball (j) is the scattered energy of the metal ball when the receiving antenna moves at an angle j on the slide rail, σ ball (j) is the bistatic scattering cross-section of the metal ball when the receiving antenna moves at an angle j on the rail.

[0024] Furthermore, in step 1, a SOLT calibration is performed on the vector network analyzer using standard calibration components to correct the system error caused by the non-ideal internal components of the vector network analyzer and the drift error caused by temperature change.

[0025] Beneficial effects:

[0026] 1. The present invention provides a blackbody bistatic scattered energy measurement device, which mainly includes five parts: a vector network analyzer, a transceiver antenna, a fixed bracket, a rotating turntable, and a slide rail. The rotating turntable and the slide rail rotate in coordination to comprehensively measure the echo amplitude of the blackbody at different angles. In other words, the present invention can accurately measure the scattered energy of the blackbody at different angles, and then calculate the scattering rate of the blackbody, comprehensively obtain the scattering characteristics of the blackbody in different directions, and achieve high-precision value traceability of the blackbody brightness temperature. In addition, the measurement device of the present invention is scalable and universal, and can meet the measurement needs of blackbodies of various specifications.

[0027] 2. The present invention provides a blackbody bistatic scattered energy measurement method. When measuring the scattering rate of a microwave-calibrated blackbody, it is necessary to perform RCS calibration on the blackbody scattered energy. To this end, the present invention uses a metal sphere as a calibration standard. By measuring the scattered energy of the metal sphere, a benchmark is provided for subsequent blackbody RCS calibration. Ultimately, the scattering factor of the blackbody can be accurately measured, and the scattering characteristics of the blackbody in different directions can be comprehensively obtained, thereby achieving high-precision traceability of the blackbody brightness temperature.

[0028] 3. The present invention provides a blackbody bistatic scattered energy measurement method, which is combined with an accurate equipment calibration process to eliminate systematic errors and improve the reliability of measurement results. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 An example diagram of a bistatic scattered energy measurement device provided by the present invention;

[0030] Figure 2 A flow chart of the operating steps of the blackbody bistatic scattered energy measurement method provided by the present invention;

[0031] Figure 3 This is a schematic diagram of the measurement of a metal ball mounted in a darkroom provided by the present invention. DETAILED DESCRIPTION

[0032] In order to enable those skilled in the art to better understand the solution of the present application, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application.

[0033] The present invention provides a blackbody bistatic scattered energy measurement method and device. The idea is to first calibrate the measurement device, that is, perform error correction on the vector network analyzer and use a metal sphere to perform RCS calibration. Then, through the bistatic scattered energy measurement method, the scattered energy of the blackbody at different angles is accurately measured, and the scattering rate of the blackbody is obtained.

[0034] like Figure 1 As shown, a blackbody bistatic scattered energy measurement device includes a vector network analyzer, a transmitting and receiving antenna, a fixed bracket, a rotating turntable, and a slide rail. The fixed bracket is divided into a base and a turntable bracket. The rotating turntable is mounted on the base via the turntable bracket, and a microwave calibration blackbody or metal ball is mounted on the rotating turntable. The slide rail is mounted on the base, and both the transmitting antenna and the receiving antenna are mounted on the slide rail. The transmitting antenna is fixed on the slide rail and is located directly below the microwave calibration blackbody or metal ball. The receiving antenna can be moved to different positions on the slide rail. The vector network analyzer is connected to the transmitting antenna and the receiving antenna respectively. The functions of each component are as follows:

[0035] Vector Network Analyzer: A vector network analyzer (VNA) is used to generate RF signals and measure the scattered signals received by the receiving antenna. It provides high-precision amplitude and phase measurements and eliminates systematic errors through built-in calibration functions.

[0036] Transmitting antenna: The transmitting antenna is the signal source part of the device, responsible for radiating the RF signal output by the vector network analyzer to the microwave calibration blackbody or metal sphere. It needs to have stable transmitting power and a specific radiation pattern to ensure uniform illumination of the blackbody.

[0037] Receiving Antenna: The receiving antenna receives electromagnetic signals scattered from the microwave calibration blackbody or metal sphere and forwards the electromagnetic echo signal to the vector network analyzer. It is mounted on a movable slide and can be moved along the slide to different positions to measure the scattered signal at different angles.

[0038] Fixed bracket: It is divided into two parts: base and turntable bracket. The base is used to fix the device and bear the weight. The turntable bracket is used to fix the turntable and blackbody and bear the weight. The turntable bracket is installed on the base.

[0039] Rotating turntable: The rotating turntable is used to support and fix the microwave calibration blackbody and can rotate 360° around its axis; the rotation angle of the turntable can be precisely controlled to achieve scattering measurements of the blackbody in different directions.

[0040] Slide rail: The slide rail is shaped like a quarter circle. It is the moving track of the receiving antenna, allowing the receiving antenna to move in a specific direction during measurement. The slide rail design must ensure the receiving antenna's movement accuracy and stability.

[0041] Based on a blackbody bistatic scattered energy measurement device, the following describes in detail the implementation of the microwave calibration blackbody scattered energy measurement method of the present invention. Figure 2 As shown, the following steps are included:

[0042] Step 1: Perform error correction on the vector network analyzer.

[0043] Before measurements begin, a vector network analyzer (VNA) is used to calibrate out systematic errors caused by imperfect internal test fixtures and drift errors primarily due to temperature fluctuations. The VNA utilizes standard calibration components using the SOLT calibration method, which offers excellent accuracy and repeatability. By sequentially connecting four standard components and performing measurements, a relatively simplified equation is generated, which can be deduced and simplified to solve for the systematic error terms. Finally, these error terms are incorporated into the error correction formula to complete the error correction of the DUT's measured values. Follow the instructions on the network analyzer for specific steps.

[0044] Step 2: Use a vector network analyzer with error correction to measure and accumulate the scattered energy of the metal ball at different angles.

[0045] When measuring the scattering rate of microwave calibration blackbody, it is necessary to perform RCS calibration on the blackbody scattered energy. To this end, this step uses a metal ball as a calibration standard, and by measuring the scattered energy of the metal ball, it provides a benchmark for the subsequent blackbody RCS calibration. Figure 3 As shown, the measurement location is selected in a microwave darkroom, and the equipment is connected. The transmitting antenna is always facing the turntable that fixes the metal ball. The receiving antenna is placed on a circular slide with the metal ball as the center and faces the metal ball. The receiving antenna adjusts the distance from the transmitting antenna, that is, slides along the slide to measure the scattered energy of the metal ball in different directions. Ensure that the relative positions between the transmitting antenna, the metal ball and the receiving antenna are accurate. Due to the isotropic scattering properties of the metal ball, the turntable that fixes the metal ball does not move, and the receiving antenna only needs to move 90° for measurement. Whenever the receiving antenna moves a certain angle j along the slide, the electromagnetic echo signal of the metal ball at the angle j is collected for a period of time. The electromagnetic echo signal at the set angle j is accumulated by the error-corrected vector network analyzer, and the scattering energy of the metal ball at this angle is obtained, which is recorded as e ball (j) In this way, the scattered energy of the metal ball at different angles of the receiving antenna is gradually measured, and the measurement process is completed. This process requires ensuring the stability and consistency of the measurement environment to ensure an accurate error factor.

[0046] Step 3: When the turntable and the slide rail rotate in coordination, the error-corrected vector network analyzer is used to measure and accumulate the scattered energy of the microwave calibration blackbody at different angles.

[0047] After error calibration is completed, the echo amplitude of the microwave calibration blackbody is measured. This step uses the coordinated rotation of the turntable and the slide rail to comprehensively measure the echo amplitude of the blackbody at different angles. The specific operation is as follows:

[0048] 1. The measurement location is selected in a microwave anechoic chamber. Connect the equipment, ensuring that the transmitting antenna always faces the blackbody turntable. The turntable, which holds the blackbody, rotates with its axis radial to the transmitting antenna. The receiving antenna is placed on a circular slide centered on the blackbody, facing the microwave calibration blackbody. The receiving antenna adjusts its distance from the transmitting antenna, sliding along the slide to measure the scattered energy of the microwave calibration blackbody in different directions. Ensure that the relative positions of the transmitting antenna, microwave calibration blackbody, and receiving antenna are accurate.

[0049] 2. The transmitting antenna illuminates the microwave calibration blackbody at a fixed power. The transmitting antenna power needs to be adjusted appropriately according to the characteristics of the microwave calibration blackbody to ensure that the microwave calibration blackbody can fully absorb and scatter electromagnetic energy.

[0050] 3. The microwave calibration blackbody rotates with the radial direction of the transmitting antenna as the rotation axis. Every time it rotates a certain angle i, the receiving antenna moves a certain angle j along the slide rail. The electromagnetic echo signal of the blackbody at the angle combination (i, j) is collected for a period of time. The electromagnetic echo signal at the angle combination (i, j) is accumulated by the error-corrected vector network analyzer to obtain the scattering energy e of the microwave calibration blackbody at this angle. scatter (i, j). In this way, the echo amplitude of the microwave calibration blackbody is measured step by step at different angles. The measurement process ends when the microwave calibration blackbody completes a 360° rotation and the receiving antenna completes a 90° movement at each degree. At this point, the scattered energy data of the microwave calibration blackbody in all directions has been obtained.

[0051] Step 4: Obtain the scattering rate of the microwave calibration blackbody according to the scattering energy of the metal ball at different angles and the scattering energy of the microwave calibration blackbody at different angles.

[0052] After obtaining the scattered energy at each angle, the scattering rate of the blackbody at each angle is calculated based on the scattered energy measured by the metal ball within a 90° range:

[0053]

[0054] Where η represents the scattering rate, i is the rotation angle of the rotating turntable, and the value range of i is 0° to 360°, j is the moving angle of the receiving antenna on the slide rail, and the value range of j is 0° to 90°, e scatter (i, j) is the scattered energy of the microwave calibration blackbody when the rotation angle of the rotating turntable is i and the moving angle of the receiving antenna on the slide is j, e ball (j) is the scattered energy of the metal ball when the receiving antenna moves at an angle j on the slide rail, σ ball (j) represents the bistatic scattering cross section RCS of the metal ball when the receiving antenna moves j degrees, which can be obtained through simulation.

[0055] Therefore, the present invention provides a method and device for measuring blackbody bistatic scattered energy. The method is applicable to different models of blackbodies. By using the experimental equipment and experimental process described in the present invention, accurate measurement of blackbody scattered energy can be achieved.

[0056] Of course, the present invention may have many other embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art may of course make various corresponding changes and modifications based on the present invention, but these corresponding changes and modifications should all fall within the scope of protection of the claims attached to the present invention.

Claims

1. A blackbody bistatic scattered energy measurement device, characterized in that: It includes a vector network analyzer, a transmitting and receiving antenna, a fixed bracket, a rotating turntable, and a slide rail. The fixed bracket is divided into a base and a turntable bracket. The rotating turntable is mounted on the base through the turntable bracket, and a microwave calibration blackbody or metal ball is mounted on the rotating turntable. The slide rail is mounted on the base, and the transmitting antenna and the receiving antenna are both mounted on the slide rail. The transmitting antenna is fixed on the slide rail and is located directly below the microwave calibration blackbody or metal ball. The receiving antenna can be moved to different positions on the slide rail. The vector network analyzer is connected to the transmitting antenna and the receiving antenna respectively. The transmitting antenna is used to radiate the radio frequency signal output by the vector network analyzer onto the microwave calibration blackbody or metal sphere; the receiving antenna is used to receive the electromagnetic echo signal scattered back from the microwave calibration blackbody or metal sphere and forward the electromagnetic echo signal to the vector network analyzer.

2. A blackbody bistatic scattered energy measurement device according to claim 1, characterized in that: The shape of the slide rail is a quarter arc.

3. The blackbody bistatic scattered energy measurement device according to claim 1, characterized in that: The transmitting antenna is always facing the rotating turntable on which the microwave calibration blackbody or metal ball is fixed, and the rotating turntable can rotate 360° with the radial direction of the transmitting antenna as the rotation axis; The center of the slide rail coincides with the position of the microwave calibration black body or the metal ball, and the receiving antenna is directly opposite to the microwave calibration black body or the metal ball on the slide rail.

4. The blackbody bistatic scattered energy measurement device according to claim 1, wherein: The measurement location is selected in a microwave darkroom.

5. A method for measuring blackbody bistatic scattered energy based on the blackbody bistatic scattered energy measurement device according to claim 1, characterized in that: The following steps are involved: Step 1: Perform error correction on the vector network analyzer; Step 2: Use a vector network analyzer with error correction to measure and accumulate the scattered energy of the metal ball at different angles; Step 3: Use the error-corrected vector network analyzer to measure and accumulate the scattered energy of the microwave calibration blackbody at different angles; Step 4: Obtain the scattering rate of the microwave calibration blackbody according to the scattering energy of the metal ball at different angles and the scattering energy of the microwave calibration blackbody at different angles.

6. A method for measuring blackbody bistatic scattered energy according to claim 5, characterized in that: In step 2, the method for measuring and accumulating the scattered energy of the metal ball at different angles using an error-corrected vector network analyzer is as follows: A metal ball is mounted on a rotating turntable, the rotating turntable on which the metal ball is mounted is fixed, and the receiving antenna is continuously moved according to a set step length, and the moving angle range of the receiving antenna on the slide rail is 0° to 90°. Whenever the receiving antenna moves a set angle j along the slide rail, the electromagnetic echo signal of the metal ball at the set angle j within a set time period is collected by the receiving antenna. The electromagnetic echo signal at the set angle j is accumulated by the error-corrected vector network analyzer to obtain the scattering energy e of the metal ball at the set angle j. ball (j).

7. The method for measuring blackbody bistatic scattered energy according to claim 5, wherein: In step 3, the method for measuring and accumulating the scattered energy of the microwave calibration blackbody at different angles using the error-corrected vector network analyzer is as follows: The measurement location is selected in a microwave darkroom, and the microwave calibration blackbody is installed on a rotating turntable. The rotating turntable drives the microwave calibration blackbody to rotate with the radial direction of the transmitting antenna as the rotation axis. Every time it rotates a set angle i, the receiving antenna moves along the slide rail to set an angle j. The electromagnetic echo signal of the microwave calibration blackbody at the angle combination (i, j) within a set time period is collected by the receiving antenna. The electromagnetic echo signal at the angle combination (i, j) is accumulated by the error-corrected vector network analyzer to obtain the scattering energy e of the microwave calibration blackbody at the angle combination (i, j). scatter (i, j); and so on, gradually measure the scattered energy of the microwave calibration blackbody at different angle combinations until the microwave calibration blackbody completes a 360° rotation and the receiving antenna completes a 90° movement at each degree, and the measurement process is completed.

8. The method for measuring blackbody bistatic scattered energy according to claim 7, wherein: The transmitting antenna irradiates the microwave calibration blackbody with a fixed power, wherein the power of the transmitting antenna needs to be adjusted according to the characteristics of the microwave calibration blackbody to ensure that the microwave calibration blackbody can fully absorb and scatter electromagnetic energy.

9. The method for measuring blackbody bistatic scattered energy according to claim 5, wherein: In step 4, the calculation method of the scattering rate of the microwave calibration blackbody is as follows: Where η is the scattering rate of the microwave calibration blackbody, i is the rotation angle of the rotating turntable, and the value range of i is 0° to 360°, j is the moving angle of the receiving antenna on the slide rail, and the value range of j is 0° to 90°, e scatter (i, j) is the scattered energy of the microwave calibration blackbody when the rotation angle of the rotating turntable is i and the moving angle of the receiving antenna on the slide is j, e ball (j) is the scattered energy of the metal ball when the receiving antenna moves on the slide rail at an angle of j, σ ball (j) is the bistatic scattering cross-section of the metal ball when the receiving antenna moves at an angle j on the rail.

10. The method for measuring blackbody bistatic scattered energy according to claim 5, wherein: In step 1, a SOLT calibration is performed on the vector network analyzer using standard calibration components to correct the systematic error caused by the non-ideal internal components of the vector network analyzer and the drift error caused by temperature changes.

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