Airborne radar antenna integrated external field dynamic test system and test method

Abstract

The invention provides an airborne radar antenna integrated external field dynamic test system and test method. The system comprises a liftable azimuth turntable and a mobile square cabin arranged on a carrier. The azimuth turntable is used for mounting to-be-tested equipment and providing height adjustment and azimuth adjustment; the movable square cabin comprises a mechanical arm cabin capable of being opened and closed and a control cabin, a multi-degree-of-freedom mechanical arm is arranged in the mechanical arm cabin, a test probe is arranged on the mechanical arm and used for interacting with an antenna of equipment to be tested, the mechanical arm is provided with a movable support, and the movable support is used for providing displacement of the mechanical arm in the X direction, the Y direction and the Z direction; the mechanical arm and the movable support execute scanning action in the testing process of the testing probe; and the control cabin is used for accommodating a user to carry out field test operation. Electromagnetic data near-far field sampling is carried out through the mechanical arm convenient to move, the influence of a space multipath effect on a test result is filtered through an algorithm and hardware configuration, and airborne radar antenna integrated external field test is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of antenna field testing, and in particular to an integrated field dynamic testing system and a testing method for an airborne radar antenna. Background Art

[0002] Antenna is a vital component in wireless communication system, so its performance evaluation is very important. Antenna testing can be divided into indoor testing and outdoor testing.

[0003] Indoor test systems are generally built in microwave darkrooms. By laying absorbing materials on the walls around the microwave darkroom, the electromagnetic waves irradiating the walls can be greatly weakened or absorbed, thus forming a relatively pure ideal test environment. However, when the electrical size of the antenna to be tested is large, the size of the microwave darkroom may be difficult to meet the conditions.

[0004] Outdoor test systems are generally built in relatively open areas, where the electromagnetic environment is complex and uncontrollable. There are problems such as ground reflection and diffraction in the test site. The ground reflection during the test can be minimized by setting up the antenna, such as the antenna elevated method, ground reflection method or slant range field method. At present, field tests usually use an elevated test method. When using this test method, the antenna under test and the auxiliary antenna are set up at a certain height to reduce the reflection interference generated by the ground and the surrounding environment. However, traditional field test methods often fail to fully consider the dynamic characteristics of the antenna during actual use, and therefore cannot provide a complete performance evaluation. In addition, setting up and moving the antenna is time-consuming and labor-intensive.

[0005] Related technologies use drones to carry auxiliary equipment to perform sampling tests on the antenna under test in the air. However, this technology is limited by the positioning accuracy and flight time of drones in the air, and the test dynamic range of this method is small, which affects the complete performance evaluation of the antenna. Summary of the invention

[0006] The invention provides an integrated outdoor dynamic test system and a test method for an airborne radar antenna, which solves the problem of how to effectively perform outdoor testing of the antenna.

[0007] In order to achieve the above objectives, this application adopts the following technical solutions:

[0008] In a first aspect, an integrated field dynamic test system for an airborne radar antenna is provided, comprising:

[0009] A liftable azimuth turntable and a mobile cabin mounted on a carrier;

[0010] The azimuth turntable is used to install the device to be tested and provides height adjustment and azimuth adjustment;

[0011] The mobile cabin includes an openable and closable robotic arm cabin and a control cabin. A robotic arm with multiple degrees of freedom is arranged in the robotic arm cabin. A test probe is arranged on the robotic arm for interacting with the antenna of the device under test. The robotic arm is configured with a mobile bracket, and the mobile bracket is used to provide displacement of the robotic arm in the X, Y, and Z directions; the robotic arm and the mobile bracket perform scanning actions during the test probe test process; the control cabin is used to accommodate users to perform field test operations.

[0012] In a first possible implementation manner of the first aspect, the field test operation includes cylindrical near-field and quasi-far-field testing;

[0013] For the low-frequency antenna to be tested: the device to be tested is fixedly mounted on the azimuth turntable, the mechanical arm is placed at a set distance from the center of the azimuth turntable, the azimuth plane rotation and lifting of the azimuth turntable cooperate with the Y-direction scanning of the mechanical arm, and the azimuth turntable rotates in azimuth, thereby realizing cylindrical near-field testing; the azimuth turntable only rotates in azimuth to realize quasi-far-field testing;

[0014] For the high-frequency antenna to be tested: the device to be tested is fixedly mounted on the azimuth turntable, the robotic arm is extended to a set distance close to the antenna interface of the device to be tested, the azimuth turntable rotates and lifts in azimuth to cooperate with the Y-direction scanning of the robotic arm to achieve cylindrical near-field testing of the high-frequency antenna; the cylindrical near-field data is converted into a far-field radiation pattern through mathematical methods to achieve quasi-far-field testing.

[0015] In a second possible implementation of the first aspect, the test system also includes a digital filtering module, which is used to translate the coordinate origin of the antenna radiation pattern to the physical center of the antenna by mathematical means, and eliminate environmental reflections of the test field by digital microwave darkroom filtering technology.

[0016] In a third possible implementation manner of the first aspect, the test system further includes an optical positioning device for assisting in achieving precise positioning.

[0017] In a fourth possible implementation of the first aspect, the test system also includes a radio frequency subsystem, which includes a receiver, a standard gain antenna, a radio frequency box and a phase-stable test cable; the receiver is responsible for generating an excitation signal and collecting test data; the standard gain antenna is used as a reference; the radio frequency box controls the switching of transmit and receive states and adjusts the dynamic range of the system; the phase-stable test cable is used to ensure phase stability during signal transmission.

[0018] In a fifth possible implementation manner of the first aspect, the test system further includes a software subsystem, and the software subsystem includes airborne radar antenna integrated test detection software, fast quasi-far field measurement software, and phase-free measurement analysis software;

[0019] The airborne radar antenna integrated test and detection software is used to test the performance of the whole machine in an outdoor environment, including a cylindrical near-field test function, to achieve automated rapid testing, and to display test results in real time;

[0020] The fast quasi-far-field test software is used to realize fast testing and real-time display under quasi-far-field conditions; analyze the measurement data, including at least one of the following: directivity coefficient, beam width, null point position, null point depth, side lobe position, side lobe level, cross polarization, circular polarization, and axial ratio analysis functions.

[0021] Based on the fifth possible implementation manner of the first aspect, in a sixth possible implementation manner of the first aspect, the test system further includes a control subsystem, and the control subsystem includes an RTC real-time controller, a data processing computer, and a control computer;

[0022] The RTC real-time controller is used to manage complex timing control;

[0023] The data processing computer and the control computer are used to run the software subsystem and process data.

[0024] In a second aspect, a method for outdoor dynamic testing of an integrated airborne radar antenna is provided, and an outdoor dynamic test is performed based on the test system as described in the first aspect, including:

[0025] Install the device under test on a liftable azimuth turntable, and configure the robotic arm and test probe to the set position;

[0026] The azimuth turntable is rotated and lifted in the azimuth plane to scan in coordination with the mechanical arm to obtain near-field data, including electric field strength values;

[0027] Convert the electric field intensity in the cylindrical coordinate system into the expression in the spherical coordinate system;

[0028] Integrate the transformed expression and use the stationary phase method to approximately solve it;

[0029] The weighting coefficients are calculated from the measured near-field values ​​using the orthogonality between the vector wave functions and ;

[0030] Substitute the weighted coefficient into the far-field electric field formula to obtain the far-field pattern of the antenna;

[0031] Translate the coordinate origin of the antenna pattern to the physical center of the antenna;

[0032] Mode filtering is performed using digital microwave darkroom filtering technology.

[0033] In a first possible implementation manner of the second aspect, assuming that the radius of the minimum cylindrical surface surrounding the antenna is a, then in the passive region where ρ ≥ a, the electric field strength can be expressed as two vector wave functions: and A linear combination of:

[0034]

[0035] in: and is the weighting coefficient, m represents the number of modes, k z = kcosθ, k represents the wave number, ρ, z is the three base coordinates of the cylindrical coordinate system, where the vector wave function and It is expressed as:

[0036]

[0037]

[0038] Where: k z = kcosθ, k z =ksinθ, j represents an imaginary number, represents the Hankel function, represents the derivative of the Hankel function, and are two unit vectors in the spherical coordinate system;

[0039] The result of the approximate solution using the stationary phase method is:

[0040]

[0041] The method of calculating the weighting coefficient by using the orthogonality between the vector wave function and the near field value obtained by measurement includes: using a probe with known characteristics to scan the near field value obtained on the cylindrical surface and and and The weighting coefficient can be obtained:

[0042]

[0043]

[0044] When ρ→∞, ignore the relationship with θ, The irrelevant factors can be obtained as follows:

[0045]

[0046] in, and is the weighting coefficient, m represents the number of modes, k z = kcosθ, k represents the wave number, ρ, z is the three base coordinates of the cylindrical coordinate system, r is the distance from the test point to the origin of the test coordinate system O-xyz, j represents an imaginary number, represents the Hankel function, represents the derivative of the Hankel function, and are two unit vectors in spherical coordinates.

[0047] Based on the first possible implementation manner of the second aspect, in a second possible implementation manner of the second aspect, the mode filtering by using the digital microwave darkroom filtering technology includes:

[0048] The amplitude pattern functions are the same in the two coordinate systems, but there is a phase difference between the phase pattern functions:

[0049]

[0050] Where r' is the distance between the two coordinate systems; r is the distance from the test point P to the origin of the test coordinate system O-xyz. In spherical coordinates, the corresponding relationship between the tangential electric field pattern function of the antenna under test in the coordinate system O'-x'y'z' and the coordinate system O-xyz is as follows:

[0051]

[0052] Where r' is the distance between the two coordinate systems, r is the distance from the test point to the origin of the test coordinate system O-xyz, k represents the wave number, m represents the mode number, and j represents the imaginary number;

[0053] When r→∞ asymptotically the far-field data can be expressed as:

[0054]

[0055]

[0056] The above formula can be transformed into discrete Fourier transform, and its inverse transform is shown as follows:

[0057]

[0058]

[0059] Based on the minimum cylindrical radius, the mode coefficient can be determined and The order of the filter is designed to achieve mode filtering.

[0060] in, and is the mode coefficient, k represents the wave number, r is the distance from the test point to the origin of the test coordinate system O-xyz, m represents the mode number, and j represents an imaginary number.

[0061] This application uses a mobile manipulator to perform near-field and far-field sampling of electromagnetic data, and filters out the impact of spatial multipath effects on test results through algorithms and hardware configurations. It can monitor and collect electromagnetic environments faced by special aircraft, verify the electromagnetic compatibility of the entire aircraft system after the mission system is installed, and realize integrated testing of airborne radar antennas. It is of great significance to solve problems such as limited indoor space, inaccurate existing field test results, poor adaptability to test requirements and scenarios, small dynamic range, long deployment time, and high resource consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] Figure 1 A test state reference diagram of an airborne radar antenna integrated field dynamic test system provided in an embodiment of the present application;

[0063] Figure 2 A three-dimensional diagram of a mechanical subsystem provided in an embodiment of the present application;

[0064] Figure 3 A three-dimensional diagram of another mechanical subsystem provided in an embodiment of the present application;

[0065] Figure 4 A framework diagram of an airborne radar antenna integrated field dynamic test system provided in an embodiment of the present application;

[0066] Figure 5 A schematic flow chart of an integrated field dynamic test method for an airborne radar antenna provided in an embodiment of the present application;

[0067] Figure 6 A schematic diagram of coordinate translation provided in an embodiment of the present application;

[0068] Figure 7 A control block diagram of an RTC real-time controller provided in an embodiment of the present application;

[0069] Figure 8 An automatic optimization interface for test time and scan speed provided in an embodiment of the present application;

[0070] Fig. 9 A breakpoint resume scanning interface provided in an embodiment of the present application;

[0071] Fig.10 An analysis algorithm selection interface provided in an embodiment of the present application;

[0072] Fig.11A diagram of the results of a digital microwave darkroom filtering experiment provided in an embodiment of the present application.

[0073] Reference numerals:

[0074] Azimuth turntable 1; mobile cabin 2; mechanical arm cabin 201; control cabin 202; mechanical arm 3; mobile bracket 4. DETAILED DESCRIPTION

[0075] In order to further explain the technical means and effects adopted by the present invention to achieve the predetermined purpose, the technical solutions in the embodiments of the present application are clearly described. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field belong to the scope of protection of the present application.

[0076] The terms "first", "second", etc. in the specification and claims of the present application are used to distinguish similar objects, and are not used to describe a specific order or sequence. It should be understood that the terms used in this way are interchangeable where appropriate, so that the embodiments of the present application can be implemented in an order other than those illustrated or described herein, and the objects distinguished by "first", "second", etc. are generally of one type, and the number of objects is not limited. For example, the first object can be one or more. In addition, "and / or" in the specification and claims represents at least one of the connected objects, and the character " / " generally indicates that the objects associated with each other are in an "or" relationship.

[0077] The description of the method flow in the specification of the present application and the steps of the flowchart in the drawings of the present specification do not have to be strictly executed according to the step numbers, and the method steps can be executed in a different order. Moreover, some steps can be omitted, multiple steps can be combined into one step, and / or one step can be decomposed into multiple steps.

[0078] The following is a detailed description of the recommendation method, device and medium based on hypergraph and multi-behavior comparative learning provided in the embodiments of the present application in combination with the accompanying drawings and preferred embodiments.

[0079] First, the application scenario of the recommendation method based on hypergraph and multi-behavior comparative learning in the embodiment of the present application is described in detail.

[0080] Although testing the antenna in a microwave darkroom can achieve higher test accuracy, the space for indoor testing is limited. When testing indoors, it may be affected by space limitations, and the absorbing materials used in microwave darkrooms are expensive and easily damaged. Therefore, when the electrical size of the antenna to be tested is large, it is necessary to test the antenna outdoors in an open and low-cost area.

[0081] Outdoor test systems are generally built in relatively open areas, where the electromagnetic environment is complex and uncontrollable. There are problems such as ground reflection and diffraction in the test site. The ground reflection during the test can be minimized by setting the antenna, such as the antenna elevated method, ground reflection method or slant range field method. At present, field tests usually use an elevated test method. When using this test method, the antenna under test and the auxiliary antenna are set at a certain height to reduce the reflection interference generated by the ground and the surrounding environment. During outdoor testing, the wireless signal will also be affected by factors such as climate, terrain, buildings and vegetation coverage during propagation, which will affect the accuracy of the antenna test results to a certain extent. During the test, the dynamic characteristics of the antenna in actual use are often not fully considered, so a complete performance evaluation cannot be provided. In addition, traditional outdoor tests usually use an elevated test method, which is not only difficult to move the antenna, but also takes a lot of time to set up. There is an urgent need for a flexible outdoor operating system and a highly accurate test method.

[0082] In view of the above problems such as insufficient darkroom test space, inaccurate field test results, poor adaptability of the test site to different test requirements and scenarios, and long time and high resource consumption for deploying the test site, the present application provides an integrated field dynamic test system for airborne radar antenna based on a movable test vehicle, which aims to conduct field dynamic tests on the premise of ensuring the accuracy of the test results. The system adopts a combination of an azimuth turntable and a mechanical arm to achieve cylindrical near-field and rapid quasi-far-field testing; and the system applies digital microwave darkroom filtering technology to suppress the influence of clutter in the field environment; at the same time, this test system is equipped with a movable vehicle-mounted probe to achieve long-distance testing, so that the system can be better applied to the performance testing of the whole machine in the field environment.

[0083] See also Figure 1-4 , the present application embodiment provides an airborne radar antenna integrated field dynamic test system, such as Figure 1-4 As shown, the test system of the embodiment of the present application includes: a mechanical subsystem, a radio frequency subsystem, a software subsystem and a control subsystem.

[0084] The mechanical subsystem includes a liftable azimuth turntable 1 and a mobile cabin 2 arranged on a carrier; the azimuth turntable 1 is used to install the device to be tested, and provides height adjustment and azimuth adjustment to meet the test requirements at different heights; the mobile cabin 2 ensures that the entire system can be easily moved to the test site through the carrier, and the mobile cabin 2 includes an openable and closable mechanical arm cabin 201 and a control cabin 202. The mechanical arm cabin 201 is provided with a multi-degree-of-freedom mechanical arm 3, and the mechanical arm 3 is equipped with a mobile bracket 4. The mobile bracket 4 is used to provide displacement of the mechanical arm 3 in the X, Y, and Z directions. The mechanical arm 3 and the mobile bracket 4 perform scanning actions during the test; the control cabin 202 is used to accommodate users to perform test operations, and the radio frequency subsystem, control subsystem, and software subsystem are arranged in the control cabin 202. The mechanical subsystem also includes an optical positioning device to assist in achieving precise positioning.

[0085] The RF subsystem includes a receiver, a test probe, a standard gain antenna, a RF box, and a phase-stable test cable. The receiver is responsible for generating an excitation signal and collecting test data; the test probe is set on the mechanical arm 3 to interact with the antenna of the device under test and collect electromagnetic data; the standard gain antenna is used as a reference; the RF box controls the switching of the receiving and transmitting states and adjusts the dynamic range of the system; the phase-stable test cable ensures the phase stability during signal transmission.

[0086] The software subsystem includes airborne radar antenna integrated test and detection software, fast quasi-far-field measurement software, digital filtering module and phase-free measurement and analysis software. These software tools support automated test processes, data analysis, and monitoring of test progress through a graphical interface. The coordinate origin of the antenna pattern is mathematically translated to the physical center of the antenna, and the environmental reflection of the test field is eliminated through digital microwave darkroom filtering technology. During field testing, environmental reflection is the main error source of the measurement system. After obtaining the engineering data file, the residual environmental reflection of the test field can be eliminated through digital microwave darkroom filtering technology, thereby improving the performance of the traditional far-field test field.

[0087] The control subsystem includes the RTC real-time controller, data processing computer and control computer. The RTC real-time controller is the core control component used to manage complex timing control; the data processing computer and control computer are used to run the software subsystem and process data.

[0088] For example, the lifting height of the azimuth turntable 1 is 4.5m, and the effective stroke of the robot arm 3 in the Y direction is 1.5m. When the azimuth turntable 1 is not raised, the lowest point of the probe on the robot arm 3 is 3m from the ground. When the azimuth turntable 1 and the robot arm 3 are both raised to the highest point, the probe is 9m from the ground. Therefore, the robot arm 3 and the lifting platform can cooperate to achieve a total scanning range of 6m in the Y direction. The test probe realizes precise positioning of the measuring point through the robot arm 3.

[0089] During the test, the robot arm 3 scans 1.5m each time, the azimuth turntable 1 is raised by a hydraulic device in a large step of 1.5m, and the robot arm 3 continues to scan the next 1.5m until the data collection on one Y axis is completed. At the same time, the robot arm 3 can also extend 5m in the X direction as needed.

[0090] When the system tests the low-frequency antenna to be tested, the device to be tested is fixedly installed on the azimuth turntable 1, and the mechanical arm 3 is placed at a position about 10m away from the center of the turntable. The mechanical arm 3 scans in the Y direction and the turntable rotates in azimuth, thereby realizing the cylindrical near-field test. At the same time, the turntable only rotates in the azimuth plane, and the quasi-far-field test of the azimuth plane can also be realized.

[0091] When the system tests the high-frequency antenna under test, the device under test is installed on the azimuth turntable 1, and the mechanical arm 3 is placed next to the device under test and extended 5 meters away, so that the test probe is as close to the antenna surface as possible. The antenna of the device under test is rotated in the azimuth plane through the azimuth turntable 1, and the mechanical arm 3 scans in the Y direction, thereby realizing the cylindrical near-field test of the high-frequency antenna.

[0092] In the specific implementation process, the entire system is placed in a cabin of about 5m×2.5m×2.5m when folded and transported, namely, a mobile cabin 2, which includes a mechanical arm cabin 201 and a control cabin 202, and the cabin is placed on a transport vehicle. The mechanical arm cabin 201 is used to store the mechanical arm 3, and the operator can operate the test system in the control cabin 202; the transport vehicle can quickly reach the test site, then open the back of the cabin and the ceiling, adjust the support level, and unfold the mechanical arm 3; the operator can select cylindrical near-field test (airborne radar antenna integrated test) and far-field test (including quasi-far-field test) in the initial interface of the software, and then initialize the test equipment and inject test parameters into the test equipment.

[0093] The main functions of the airborne radar antenna integrated test and detection software are: to test the performance of the whole machine in the field environment, with cylindrical near-field test function, can realize automatic rapid test, and display the test results in real time. The main functions of the rapid quasi-far-field test software are: to realize rapid test and real-time display under quasi-far-field conditions; to analyze the measurement data, including directivity coefficient, beam width, null position, null depth, sidelobe position, sidelobe level, cross polarization, circular polarization, axial ratio analysis function, etc.

[0094] See also Figure 5 The present application embodiment provides an integrated field dynamic test method for an airborne radar antenna, such as Figure 5 As shown, the testing method of the embodiment of the present application includes:

[0095] Step S1, installing the device to be tested on a liftable azimuth turntable, and configuring the mechanical arm and the test probe to a set position;

[0096] Step S2, scanning by rotating and lifting the azimuth turntable in the azimuth plane in coordination with the mechanical arm to obtain near-field data, including electric field strength values;

[0097] Step S3, converting the electric field intensity in the cylindrical coordinate system into an expression in the spherical coordinate system;

[0098] Step S4, performing integral calculation on the converted expression and using the stationary phase method to approximately solve it;

[0099] Step S5, using the orthogonality between the vector wave functions and , calculating the weighting coefficient through the measured near-field value;

[0100] Step S6, substituting the weighted coefficient into the far-field electric field formula to obtain the far-field radiation pattern of the antenna;

[0101] Step S7, translating the coordinate origin of the antenna pattern to the physical center of the antenna;

[0102] Step S8, performing mode filtering by using digital microwave darkroom filtering technology.

[0103] Specifically, the above steps are:

[0104] Cylindrical near-field measurement is to measure the field in the cylindrical space around the antenna to be measured. For antennas with small beam elevation angles and wide azimuth angles, it has more information and smaller errors than planar near-field measurement, and can provide more accurate research on antenna characteristics.

[0105] The near-field and far-field transformation based on the cylindrical mode expansion theory is the key to the realization of the cylindrical near-field measurement system of the mode filtering antenna. It expands the field established by the antenna to be tested in space into the sum of cylindrical wave functions, and obtains the antenna far-field pattern through mathematical derivation.

[0106] Assuming that the radius of the smallest cylindrical surface surrounding the antenna is a, the electric field strength in the passive region with ρ ≥ a can be expressed as two vector wave functions: and A linear combination of:

[0107]

[0108] in: and is the weighting coefficient, m represents the number of modes, k z = kcosθ, k represents the wave number, ρ, z is the three base coordinates of the cylindrical coordinate system, where the vector wave function and It is expressed as:

[0109]

[0110]

[0111] Where: k z = kcosθ, k z =ksinθ, j represents an imaginary number, represents the Hankel function, represents the derivative of the Hankel function, and are two unit vectors in spherical coordinates.

[0112] The above formula is the relationship between the field established by the antenna and the weighting function, but the calculation is difficult. To reduce the difficulty of calculation, the cylindrical coordinate system is converted to the spherical coordinate system for calculation, that is, ρ = rsinθ, z = rcosθ.

[0113] Combining the above equations and using the stationary phase method to approximate the integral, the result is:

[0114]

[0115] Using vector wave functions and Orthogonality between the near-field values ​​obtained by scanning a probe with known characteristics on a cylindrical surface and The near-field value is obtained by scanning the cylindrical surface with a probe of known characteristics. and and and The weighting coefficient can be obtained:

[0116]

[0117]

[0118] When ρ→∞, ignore the relationship with θ, The irrelevant factors can be obtained as follows:

[0119]

[0120] From the above formula, we can know that the near field and far field are related by the weighting coefficient. The weighting coefficient is obtained by the above formula. and Then substitute it into The far-field pattern is obtained.

[0121] in, and is the weighting coefficient, m represents the number of modes, k z = kcosθ, k represents the wave number, ρ, z is the three base coordinates of the cylindrical coordinate system, r is the distance from the test point to the origin of the test coordinate system O-xyz, j represents an imaginary number, represents the Hankel function, represents the derivative of the Hankel function, and are two unit vectors in spherical coordinates.

[0122] See also Figure 6 By mathematically translating the coordinate origin of the antenna pattern to the physical center of the antenna under test through coordinate translation, the energy containing multipath interference can be mainly concentrated in the high-order terms, while the mode coefficients characterizing the antenna under test are concentrated in the low-order terms, so that the high-order terms of the mode can be filtered out through the mode filter function to achieve the purpose of suppressing multipath interference. Therefore, coordinate translation is one of the keys to multipath interference suppression technology based on the mode filtering mechanism.

[0123] The amplitude pattern functions are the same in the two coordinate systems, but there is a phase difference between the phase pattern functions:

[0124]

[0125] Where r' is the distance between the two coordinate systems; r is the distance from the test point P to the origin of the test coordinate system O-xyz. In spherical coordinates, the corresponding relationship between the tangential electric field pattern function of the antenna under test in the coordinate system O'-x'y'z' and the coordinate system O-xyz is as follows:

[0126]

[0127] Where r' is the distance between the two coordinate systems, r is the distance from the test point to the origin of the test coordinate system O-xyz, k represents the wave number, m represents the mode number, and j represents the imaginary number.

[0128] For digital microwave darkroom filtering technology, the residual environmental reflections in the test field are eliminated by mode filtering. The digital filtering module calculates the mode coefficients through the far-field inversion equation to obtain the equivalent cylindrical mode coefficients representing the displacement antenna. As mentioned above, when r→∞ asymptotically, the far-field data can be expressed as:

[0129]

[0130]

[0131] The above formula can be transformed into discrete Fourier transform, and its inverse transform is easy to write, as shown below:

[0132]

[0133]

[0134] Based on the minimum cylindrical radius, the mode coefficient can be determined and The order of the filter is determined by designing different filter functions to achieve mode filtering.

[0135] in, and is the mode coefficient, k represents the wave number, r is the distance from the test point to the origin of the test coordinate system O-xyz, m represents the mode number, and j represents an imaginary number.

[0136] Exemplarily, the operation flow of book application is described below through a specific example.

[0137] Step 1: The test vehicle arrives at the test site and is ready to start testing.

[0138] The system consists of mechanical subsystem, control subsystem, software subsystem and test accessories. The mechanical subsystem includes a mechanical arm 3, a lifting platform, a mobile cabin 2 platform and an optical positioning device; the radio frequency subsystem includes a receiver, a test probe, a standard gain antenna, a radio frequency box and a phase-stable test cable; the control subsystem includes an RTC real-time controller, two computers and control cables; the software subsystem includes airborne radar antenna integrated test detection software, fast quasi-far-field measurement software, a digital filter module and phase-free measurement analysis software. The entire system is placed in a cabin of about 5m×2.5m×2.5m when folded and transported, including a mechanical arm cabin 201 and a control cabin 202, and the cabin is placed on a transport vehicle. The mechanical arm cabin 201 is used to store the mechanical arm 3. The operator can operate the test system in the control cabin 202, and the transport vehicle can quickly reach the test site, then open the back of the cabin and the ceiling, adjust the support level, and unfold the mechanical arm 3.

[0139] Step 2: Scan and sample the antenna on the target side.

[0140] like Figure 1As shown, when the system tests the low-frequency antenna to be tested, the product to be tested is installed on the azimuth turntable 1, the mechanical arm 3 is placed at a position about 10m away from the center of the turntable, the mechanical arm 3 scans in the Y direction, and the turntable rotates in azimuth, thereby realizing the cylindrical near-field test. At the same time, the turntable only rotates in the azimuth plane, and the quasi-far-field test of the azimuth plane can also be realized; as shown in the figure, when the system tests the high-frequency antenna to be tested, the product to be tested is installed on the azimuth turntable 1, and the mechanical arm 3 is placed next to the product to be tested, extending a distance of 5m, so that the test probe is as close to the antenna surface to be tested as possible. The antenna to be tested realizes azimuth plane rotation through its own pan-tilt platform, and the mechanical arm 3 scans in the Y direction, thereby realizing the cylindrical near-field test of the high-frequency antenna. During the test, every time the mechanical arm 3 scans 1.5m, the hydraulic platform rises 1.5m in a large step, and the mechanical arm 3 continues to scan the next 1.5m until the data collection on a Y axis is completed. At the same time, the mechanical arm 3 can also extend a distance of 5m in the X direction as needed. The lifting height of the lifting platform is 4.5m, and the effective stroke of the robot arm 3 in the Y direction is 1.5m. When the lifting platform is not raised, the lowest point of the probe on the robot arm 3 is 3m away from the ground. When the lifting platform and the robot arm 3 are both raised to the highest point, the probe is 9m away from the ground. Therefore, the robot arm 3 and the lifting platform can cooperate to achieve a total scanning range of 6m in the Y direction. The test probe can achieve accurate positioning of the measuring point through the robot arm 3.

[0141] Step 3: Complete the generation, amplification, transmission, reception and testing of RF signals in the RF link during the field dynamic test process through the RF subsystem.

[0142] The product to be tested is placed on the azimuth turntable 1 to achieve rotation in the azimuth plane. The test probe can accurately locate the measurement point through the mechanical arm 3. The real-time controller RTC, as the core control component of the system, realizes complex timing control during the test process. The receiver provides an excitation signal and collects test data as a receiver. The RF box at the antenna end / probe end mainly realizes the switching of the receiving and transmitting state and the adjustment of the dynamic range of the system. In a scanning process, multi-wave position and multi-frequency point tests can be performed, and the system can also select continuous wave test or pulse test according to the needs of the product to be tested.

[0143] Step 4: Complete the timing control of mechanical equipment and RF equipment through the control subsystem.

[0144] like Figure 7As shown, the lifting device of the mechanical arm 3 and the antenna turntable adopts LAN to realize data transmission and control, and the real-time positioning signal adopts TTL level signal; the antenna turntable adopts LAN to realize data transmission and control, and the real-time positioning signal adopts TTL level signal; the control of the receiver adopts LAN, and the underlying layer of the LAN control method adopts TCP / IP protocol, and the control is relatively flexible and fast. In the process of receiver testing, TTL level signal control is used to borrow a mobile phone for external triggering test; the control of the wave control extension also adopts LAN for data transportation, wave control monitoring, etc., and the wave position and frequency switching adopt TTL level signal to realize the rapid switching of wave position and frequency; the control sampling SPI protocol of the radio frequency box can realize the rapid switching of the switch radio frequency box.

[0145] Step 5: Software subsystem operation.

[0146] Airborne radar antenna integrated test software:

[0147] The operator selects the cylindrical near-field test (airborne radar antenna integrated test) on the initial interface of the software to implement the cylindrical near-field antenna test and test products in various test scenarios and test states. The main functions of the airborne radar antenna integrated test and detection software are: to test the performance of the entire machine in an outdoor environment, with a cylindrical near-field test function, which can realize automatic rapid testing and display the test results in real time. The software has: (1) a real-time monitoring interface. (2) an automatic optimization interface for test time and scan speed. The test time and scan speed can be automatically optimized according to the settings of different test frequencies and scan steps, such as Figure 8 (3) Breakpoint resume scan interface. The software has breakpoint resume and retest functions. The resume and retest positions can be specified, such as Fig. 9 shown.

[0148] Fast quasi-far field test software:

[0149] The operator selects far-field test (including quasi-far-field test) on the initial interface of the software to realize far-field test. The main functions of the fast quasi-far-field test software are: to realize fast testing and real-time display under quasi-far-field conditions. The software has: (1) multi-frequency point and multi-wavelength position interface; (2) test antenna transmit and receive mode switching interface, in addition, the polarization mode, polarization direction and other basic information of the test antenna can also be set; (3) receiver setting interface. Continuous wave and pulse parameters can be selected, and the receiver power, intermediate frequency bandwidth and other parameters can be set; (4) real-time monitoring interface. The main functions of the fast quasi-far-field analysis software are: to analyze the measurement data, including directivity coefficient, beam width, zero point position, zero point depth, sidelobe position, sidelobe level, cross polarization, circular polarization, axial ratio analysis function, etc., such as Fig.10 shown.

[0150] This application uses a vehicle-mounted mechanical arm to perform near-field and far-field sampling of electromagnetic data, and filters out the impact of spatial multipath effects on test results through algorithms and hardware configurations. It can monitor and collect electromagnetic environments faced by special aircraft, verify the electromagnetic compatibility of the entire aircraft system after the mission system is installed, and realize integrated testing of airborne radar antennas. It is of great significance to solve problems such as limited indoor space, inaccurate existing field test results, poor adaptability to test requirements and scenarios, small dynamic range, long deployment time, and high resource consumption.

[0151] The effects of this application are further illustrated below through the contents of simulation experiments.

[0152] Under the above conditions, the system is configured with a digital filtering module. During field testing, environmental reflection is the main error source of the measurement system. Digital microwave darkroom filtering technology can reduce the residual environmental reflection of the test field through pattern filtering, thereby improving the performance of the traditional far-field test field. The comparison of indoor and outdoor test results and the comparison of digital microwave darkroom filtering effects are shown in the figure. Fig.11 shown.

[0153] Fig.10 The left picture in the middle shows the measurement result before filtering, and the right picture shows the measurement result after filtering. The red solid line is the measurement result in the darkroom, the black solid line is the measurement result outdoors, and the black dotted line is the difference in the directional diagram between the darkroom measurement and the outdoor measurement. Fig.10 It can be seen that the maximum difference between the directional patterns measured in the darkroom and the outdoor measurement before filtering is about -21dB, which is a large difference, and the outdoor measurement directional pattern curve fluctuates slightly. After filtering, the maximum difference between the directional patterns of the two is about -32dB, which is 11dB lower than before filtering, and the outdoor measurement directional pattern curve is smoother. This shows that the digital microwave darkroom filtering technology can reduce the residual environmental reflection of the test field and improve the performance of traditional far-field testing.

[0154] It should be noted that, in this article, the terms "comprise", "include" or any other variant thereof are intended to cover non-exclusive inclusion, so that the process, method, article or device including a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise one..." do not exclude the presence of other identical elements in the process, method, article or device including the element. In addition, it should be pointed out that the scope of the methods and devices in the embodiments of the present application is not limited to performing functions in the order shown or discussed, and may also include performing functions in a substantially simultaneous manner or in reverse order according to the functions involved, for example, the described method may be performed in an order different from that described, and various steps may also be added, omitted, or combined. In addition, the features described with reference to certain examples may be combined in other examples.

[0155] The embodiments of the present application are described above in conjunction with the accompanying drawings, but the present application is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Under the guidance of the present application, ordinary technicians in this field can also make many forms without departing from the purpose of the present application and the scope of protection of the claims, all of which are within the protection of the present application.

Claims

1. Airborne radar antenna integrated field dynamic test system, characterized by: include: A liftable azimuth turntable and a mobile cabin mounted on a carrier; The azimuth turntable is used to install the device to be tested and provides height adjustment and azimuth adjustment; The mobile cabin includes an openable and closable robotic arm cabin and a control cabin. A robotic arm with multiple degrees of freedom is arranged in the robotic arm cabin. A test probe is arranged on the robotic arm for interacting with the antenna of the device under test. The robotic arm is configured with a mobile bracket, and the mobile bracket is used to provide displacement of the robotic arm in the X, Y, and Z directions; the robotic arm and the mobile bracket perform scanning actions during the test probe test process; the control cabin is used to accommodate users to perform field test operations.

2. The airborne radar antenna integrated field dynamic test system according to claim 1, characterized in that: The field test operation includes cylindrical near field and quasi-far field testing; For the low-frequency antenna to be tested: the device to be tested is fixedly mounted on the azimuth turntable, the mechanical arm is placed at a set distance from the center of the azimuth turntable, the azimuth plane rotation and lifting of the azimuth turntable cooperate with the Y-direction scanning of the mechanical arm, and the azimuth turntable rotates in azimuth, thereby realizing cylindrical near-field testing; the azimuth turntable only rotates in azimuth to realize quasi-far-field testing; For the high-frequency antenna to be tested: the device to be tested is fixedly mounted on the azimuth turntable, the robotic arm is extended to a set distance close to the antenna interface of the device to be tested, the azimuth turntable rotates and lifts in azimuth to cooperate with the Y-direction scanning of the robotic arm to achieve cylindrical near-field testing of the high-frequency antenna; the cylindrical near-field data is converted into a far-field radiation pattern through mathematical methods to achieve quasi-far-field testing.

3. The integrated field dynamic test system for airborne radar antenna according to claim 1 is characterized in that: The test system also includes a digital filtering module, which is used to translate the coordinate origin of the antenna pattern to the physical center of the antenna by mathematical means, and eliminate the environmental reflection of the test field by digital microwave darkroom filtering technology.

4. The integrated field dynamic test system for airborne radar antenna according to claim 1, characterized in that: The testing system also includes an optical positioning device for assisting in achieving precise positioning.

5. The integrated field dynamic test system for airborne radar antenna according to claim 1 is characterized in that: The test system also includes a radio frequency subsystem, which includes a receiver, a standard gain antenna, a radio frequency box and a phase-stable test cable; the receiver is responsible for generating an excitation signal and collecting test data; the standard gain antenna is used as a reference; the radio frequency box controls the switching of the transmit and receive states and adjusts the dynamic range of the system; the phase-stable test cable is used to ensure phase stability during signal transmission.

6. The integrated field dynamic test system for airborne radar antenna according to claim 1, characterized in that: The test system also includes a software subsystem, which includes airborne radar antenna integrated test detection software, fast quasi-far-field measurement software and phase-free measurement analysis software; The airborne radar antenna integrated test and detection software is used to test the performance of the whole machine in an outdoor environment, including a cylindrical near-field test function, to achieve automated rapid testing, and to display test results in real time; The fast quasi-far-field test software is used to realize fast testing and real-time display under quasi-far-field conditions; analyze the measurement data, including at least one of the following: directivity coefficient, beam width, null point position, null point depth, side lobe position, side lobe level, cross polarization, circular polarization, and axial ratio analysis functions.

7. The integrated field dynamic test system for airborne radar antenna according to claim 6 is characterized in that: The test system also includes a control subsystem, which includes an RTC real-time controller, a data processing computer and a control computer; The RTC real-time controller is used to manage complex timing control; The data processing computer and the control computer are used to run the software subsystem and process data.

8. An integrated field dynamic test method for airborne radar antennas, characterized in that: Performing an outfield dynamic test based on the test system according to any one of claims 1 to 7 includes: Install the device under test on a liftable azimuth turntable, and configure the robotic arm and test probe to the set position; The azimuth turntable is rotated and lifted in the azimuth plane to scan in coordination with the mechanical arm to obtain near-field data, including electric field strength values; Convert the electric field intensity in the cylindrical coordinate system into the expression in the spherical coordinate system; Integrate the transformed expression and use the stationary phase method to approximately solve it; The weighting coefficients are calculated from the measured near-field values ​​using the orthogonality between the vector wave functions and ; Substitute the weighted coefficient into the far-field electric field formula to obtain the far-field pattern of the antenna; Translate the coordinate origin of the antenna pattern to the physical center of the antenna; Mode filtering is performed using digital microwave darkroom filtering technology.

9. The method for external dynamic testing of integrated airborne radar antenna according to claim 8, characterized in that: Assuming that the radius of the smallest cylindrical surface surrounding the antenna is a, the electric field strength in the passive region with ρ ≥ a can be expressed as two vector wave functions: and A linear combination of: in: and is the weighting coefficient, m represents the number of modes, k z = kcosθ, k represents the wave number, ρ, z is the three base coordinates of the cylindrical coordinate system, where the vector wave function and It is expressed as: Where: k z = kcosθ, k z =ksinθ, j represents an imaginary number, represents the Hankel function, represents the derivative of the Hankel function, and are two unit vectors in the spherical coordinate system; The result of the approximate solution using the stationary phase method is: The method of calculating the weighting coefficient by using the orthogonality between the vector wave function and the near field value obtained by measurement includes: using a probe with known characteristics to scan the near field value obtained on the cylindrical surface and and and The weighting coefficient can be obtained: When ρ→∞, ignore the relationship with θ, The irrelevant factors can be obtained as follows: in, and is the weighting coefficient, m represents the number of modes, k z = kcosθ, k represents the wave number, ρ, z is the three base coordinates of the cylindrical coordinate system, r is the distance from the test point to the origin of the test coordinate system O-xyz, j represents an imaginary number, represents the Hankel function, represents the derivative of the Hankel function, and are two unit vectors in spherical coordinates.

10. The integrated field dynamic test method for airborne radar antenna according to claim 9, characterized in that: The mode filtering by digital microwave darkroom filtering technology includes: The amplitude pattern functions are the same in the two coordinate systems, but there is a phase difference between the phase pattern functions: Where r' is the distance between the two coordinate systems; r is the distance from the test point P to the origin of the test coordinate system O-xyz. In spherical coordinates, the corresponding relationship between the tangential electric field pattern function of the antenna under test in the coordinate system O'-x'y'z' and the coordinate system O-xyz is as follows: Where r' is the distance between the two coordinate systems, r is the distance from the test point to the origin of the test coordinate system O-xyz, k represents the wave number, m represents the mode number, and j represents the imaginary number; When r→∞ asymptotically the far-field data can be expressed as: The above formula can be transformed into discrete Fourier transform, and its inverse transform is shown as follows: Based on the minimum cylindrical radius, the mode coefficient can be determined and The order of the filter is designed to achieve mode filtering. in, and is the mode coefficient, k represents the wave number, r is the distance from the test point to the origin of the test coordinate system O-xyz, m represents the mode number, and j represents an imaginary number.

Images