Target cross polarization scattering center modeling method based on full-wave current data

Abstract

The invention provides a target cross polarization scattering center modeling method based on full-wave current data. The method comprises the steps that a target geometric model is divided into grid files; based on the grid file, calculating a target surface induction current by using a full-wave numerical method; performing orthogonal decomposition on the current to obtain a current cross polarization component; performing region segmentation on the grid file, and based on the region segmentation, segmenting a current cross polarization component to obtain cross polarization current partitions; self-adaptively extracting a cross polarization scattering contribution structure according to the current intensity sorting result of each region; determining a scattering center distribution mechanism according to the form of the regional current cross polarization component, and determining scattering center distribution by reconstructing a cross polarization scattering contribution structure; establishing a target cross polarization scattering center model based on scattering center distribution; the model and full-wave data are mutually verified, and modeling is completed when errors are judged to meet requirements. By adopting the scheme, efficient and accurate target cross polarization electromagnetic characteristic modeling is realized.

Description

Technical Field

[0001] The present application relates to the technical field of theoretical simulation of target electromagnetic characteristics, and particularly to a method and device for modeling target cross-polarization scattering centers based on full-wave current data. Background Art

[0002] Target cross-polarization electromagnetic characteristic data can enrich electromagnetic information and is one of the key basic supports for the demonstration, development, testing, and detection applications of polarization radar systems. At the same time, it can support engineering applications such as anti-jamming simulation and polarization target recognition.

[0003] In the field of theoretical simulation of target electromagnetic characteristics, electromagnetic characteristic modeling algorithms that are similar in function and complementary in performance and composed of full-wave numerical methods, high-frequency approximation methods, and hybrid methods have been formed. At the same time, electromagnetic parameterization models represented by the attribute scattering center model have been derived. The development trends and corresponding characteristics of the above modeling methods are as Figure 1 shown. Relevant achievements have achieved preliminary effects in engineering application fields such as radar parameter design, stealth penetration, detection and recognition, and target design.

[0004] The disadvantages of the existing technologies include: the full-wave numerical method has high computational complexity, large computational memory, and low computational efficiency, and it is difficult to be applied to the real-time modeling of target cross-polarization electromagnetic characteristics; the high-frequency approximation method and the hybrid high-frequency approximation method have low reliability in the calculation results of cross-polarization scattering of complex structures and have no accuracy guarantee; the analytical formulas of the existing scattering center models are all derived based on the high-frequency approximation method, and there is little research on the cross-polarization electromagnetic mechanism of complex targets, and there is still a lack of mathematical analytical formulas of scattering centers that characterize cross-polarization electromagnetic characteristics.

[0005] In summary, the existing electromagnetic modeling methods still have limitations in efficiently and accurately modeling the cross-polarization electromagnetic characteristics of targets, and there is still a certain gap from meeting the actual requirements. Summary of the Invention

[0006] The present application aims to at least solve one of the technical problems in the related technologies to some extent.

[0007] To this end, the first object of the present application is to propose a method for modeling target cross-polarization scattering centers based on full-wave current data, which realizes efficient and accurate modeling of target cross-polarization electromagnetic characteristics.

[0008] The second object of the present application is to propose a device for modeling target cross-polarization scattering centers based on full-wave current data.

[0009] To achieve the above object, the first aspect embodiment of the present application proposes a method for modeling target cross-polarization scattering centers based on full-wave current data, including:

[0010] Divide the target's geometric model into mesh files;

[0011] Based on the target grid file, the full-wave numerical method is used to calculate the induced current on the target surface;

[0012] Orthogonal decomposition of the induced current on the target surface is performed to obtain the cross-polarization component of the current;

[0013] Performing regional segmentation on the target grid file, and taking the regional segmentation result as a reference, segmenting the current cross-polarization component to obtain the cross-polarization current partition;

[0014] According to the ranking results of the current intensity in each region, the cross-polarization scattering contribution structure is adaptively extracted;

[0015] The scattering center distribution mechanism is determined based on the morphology of the cross-polarization component of the regional current, and the cross-polarization scattering center distribution is determined by reconstructing the cross-polarization scattering contribution structure;

[0016] Based on the cross-polarization scattering center distribution, a cross-polarization scattering center model of the target is established;

[0017] Based on the target grid file, the full-wave numerical method is used to calculate the RCS of the target, and the cross-polarization scattering electric field of the target is obtained based on the cross-polarization scattering center model of the target. It is judged that the error between the RCS of the target and the cross-polarization scattering electric field of the target meets the requirements, and the cross-polarization scattering center model of the target is determined.

[0018] Optionally, in one embodiment of the present application, the target surface induced current is orthogonally decomposed to obtain a current cross-polarization component, which is expressed as:

[0019]

[0020] in,

[0021]

[0022] Among them, J p is the induced current excited by the incident light in p-polarization mode, J Vp is the V polarized emission component of the induced current, J Hp is the H-polarized emission component of the induced current, is the V polarization vector, is the H polarization vector, J p (r ′ ) is the excitation point r ′ The induced current at , p is the polarization mode of the incident wave, which is V or H,

[0023] Optionally, in an embodiment of the present application, the regional segmentation of the target mesh file includes:

[0024] According to the triangular mesh vertex and index information, solve the center point coordinates and normal vectors of each mesh;

[0025] Traverse each triangular vertex index information and extract all pairs of adjacent triangles. Among them, the determination method of adjacent triangle pairs is that two triangles have two common vertices;

[0026] Solve the included angle between the normal vectors of each pair of adjacent triangles. When the included angle is less than the threshold, determine that the pair of triangles are coplanar. When the included angle is greater than the threshold, determine that the common edge of the pair of triangles is an edge structure, and extract all the edge structures of the target;

[0027] Extract all the meshes in each region based on the edge structure to complete the regional segmentation;

[0028] Based on the regional segmentation result, segment the current cross-polarization component to obtain the cross-polarization current partition, including:

[0029] Based on the regional segmentation result, obtain the current cross-polarization component of each region to obtain the cross-polarization current partition.

[0030] Optionally, in an embodiment of the present application, adaptively extract the cross-polarization scattering contribution structure according to the sorting result of the current intensity of each region, including:

[0031] Determine the electric field representation of the target by the Stratton-chu integral formula, and replace the induced current at the excitation point in the electric field representation of the target with the current cross-polarization component to obtain the expression of the cross-polarization scattering electric field;

[0032] Substitute the current cross-polarization component of the target into the expression of the cross-polarization scattering electric field to obtain the cross-polarization scattering electric field of the target;

[0033] Sort according to the average value of the current cross-polarization components of each region;

[0034] Extract regions from strong to weak based on the sorting result. After each extraction, substitute the current cross-polarization component of the extracted region into the expression of the cross-polarization scattering electric field to obtain the cross-polarization scattering electric field of the extracted region. Convert the cross-polarization scattering electric field of the extracted region into RCS and compare it with the cross-polarization scattering electric field of the target for relative error. When the relative error meets the requirements, the extraction ends, and the cross-polarization scattering contribution structure is obtained.

[0035] Optionally, in an embodiment of the present application, the electric field representation of the target is:

[0036]

[0037] where \(j\) is the imaginary unit, \(k\) is the wave number, and \(\eta\) 0 is the free space wave impedance, \(\vec{E}_i\) is the incident electric field, \(r\) is the distance from the radar to the target, \(\vec{k}_i\) is the incident wave vector, and \(s\) ′ is the integral term of the region area, \(S\) ′ is the region area;

[0038] After replacing the induced current \(J\) ′ at the excitation point \(r\) p \((r)\) with the current cross-polarization components \(J\) ′ \((r)\) HV \((r)\) ′ ), \(J\) VH \((r)\) ′ ), the expression of the cross-polarization scattered electric field is:

[0039]

[0040] The relative error is:

[0041]

[0042] where \(RCS\) extracted is the \(RCS\) of the extracted region, and \(RCS\) total is the \(RCS\) of the target.

[0043] Optionally, in an embodiment of the present application, according to the morphology of the region current cross-polarization component, the scattering center distribution mechanism is determined, including:

[0044] For the striped current, it is set as the secondary scattering caused by the dihedral angle structure, and it is determined that its scattering center is distributed at the vertex of the common edge of the dihedral angle structure;

[0045] For the point-diffused current, it is set as the tertiary scattering caused by the trihedral angle structure, and it is determined that its scattering center is distributed at the common vertex of the trihedral angle structure;

[0046] For the set line current, it is set as caused by edge diffraction, and it is determined that its scattering center is distributed at the vertex of the edge;

[0047] For the irregularly distributed current, determine the scattering centers of the striped current, point-diffused current, and line current it includes;

[0048] By reconstructing the cross-polarization scattering contribution structure, the cross-polarization scattering center distribution is determined, including:

[0049] Taking the extraction area as a reference, traverse to obtain all adjacent areas of the extraction area, and perform deletion based on the incident direction and occlusion judgment, reconstruct the dihedral angle and trihedral angle, and locate the vertex of the common edge of the dihedral angle structure or the common vertex of the trihedral angle structure;

[0050] During the traversal, determine the cross-polarized scattering center distribution based on the scattering center distribution mechanism.

[0051] Optionally, in an embodiment of the present application, based on the cross-polarized scattering center distribution, establish a cross-polarized scattering center model of the target, including:

[0052] Based on the cross-polarized scattering center distribution, use the GTD scattering center model modified based on MBPE to parametrically characterize the cross-polarization;

[0053] When performing parametric characterization, set the objective function of parameter estimation to minimize the root mean square error of the electrical frequency multi-angle RCS or maximize the TFR similarity of the time-frequency image, and perform parameter estimation on the unknown parameters.

[0054] Optionally, in an embodiment of the present application, based on the cross-polarized scattering center distribution, use the GTD scattering center model modified based on MBPE to parametrically characterize the cross-polarization, expressed as:

[0055]

[0056] where N is the number of cross-polarized scattering centers, f is the incident frequency, f c is the center frequency, α is the frequency-dependent factor, k is the wave number, is the incident wave vector, r ′ n is the position vector of the nth scattering center, ξ is the incident angle, A(ξ) is the scattering center amplitude, and based on MBPE, use a fractional rational polynomial to characterize the amplitude-dependent function of cross-polarized scattering, expressed as:

[0057]

[0058] where P = [P 1 , P 2 ,..., P m , Q = [Q 1 , Q 2 ,..., Q n-1 are the unknown parameters of the polynomial, m = n + 1;

[0059] The root mean square error is expressed as:

[0060]

[0061] where RCSsc (i) is the RCS obtained by solving the cross - polarization scattering center model, and the RCS s is the RCS of the standard data, and Q is the number of data;

[0062] The TFR similarity is expressed as:

[0063]

[0064] where S s and S c are the time - frequency image data after time - frequency transformation of the electric field of the cross - polarization scattering center model and the electric field of the standard data respectively. M×N is the dimension of the TFR data matrix, are the average values of the time - frequency image data of the cross - polarization scattering center model and the standard TFR data respectively.

[0065] Optionally, in an embodiment of the present application, determining that the error between the RCS of the target and the cross - polarization scattering electric field of the target meets the requirements includes:

[0066] Setting the error as the root - mean - square error or the TFR similarity. When the root - mean - square error is less than the first preset threshold or the TFR similarity is greater than the second preset threshold, it is determined that the error meets the requirements;

[0067] The above - mentioned method further includes:

[0068] When the error does not meet the requirements, reconstruct the cross - polarization scattering contribution structure, determine the second cross - polarization scattering center distribution, construct the second cross - polarization scattering center model of the target, obtain the second cross - polarization scattering electric field of the target based on the second cross - polarization scattering center model of the target, determine that the error between the RCS of the target and the second cross - polarization scattering electric field of the target meets the requirements, and determine the cross - polarization scattering center model of the target.

[0069] To achieve the above object, an embodiment of the second aspect of the present invention proposes a target cross - polarization scattering center modeling device based on full - wave current data, including:

[0070] A full - wave current processing module, configured to divide the geometric model of the target into grid files, calculate the induced current on the target surface using a full - wave numerical method based on the target grid files, perform orthogonal decomposition on the induced current on the target surface to obtain the current cross - polarization component, perform region segmentation on the target grid files, and divide the current cross - polarization component based on the region segmentation result to obtain cross - polarization current partitions;

[0071] The cross-polarization contribution structure extraction module is used to adaptively extract the cross-polarization scattering contribution structure according to the sorting result of the current intensity in each region, determine the scattering center distribution mechanism according to the morphology of the cross-polarization component of the regional current, and determine the cross-polarization scattering center distribution by reconstructing the cross-polarization scattering contribution structure;

[0072] The scattering center modeling module is used to establish the cross-polarization scattering center model of the target based on the cross-polarization scattering center distribution, calculate the RCS of the target by using the full-wave numerical method based on the target grid file, obtain the cross-polarization scattering electric field of the target based on the cross-polarization scattering center model of the target, judge that the error between the RCS of the target and the cross-polarization scattering electric field of the target meets the requirements, and determine the cross-polarization scattering center model of the target.

[0073] The method for modeling the cross-polarization scattering center of a target based on full-wave current data in the embodiments of the present application aims at the fast and accurate calculation requirements of cross-polarization electromagnetic scattering characteristics. By using the cross-polarization component of the current calculated by the full-wave numerical method, the cross-polarization contribution region is adaptively extracted to determine the position distribution of the scattering center; the MBPE technology is used to estimate the parameters of the scattering center amplitude in the form of a polynomial to determine the scattering center amplitude, and finally the cross-polarization scattering center model of the target is established, which can accurately and quickly generate the cross-polarization electromagnetic characteristic data of complex targets.

[0074] Some of the additional aspects and advantages of the present application will be given in the following description, some will become obvious from the following description, or will be understood through the practice of the present application. Description of the Drawings

[0075] The above and / or additional aspects and advantages of the present application will become obvious and easy to understand from the following description of the embodiments in conjunction with the drawings, where:

[0076] Figure 1 It is a schematic diagram of the development trend and corresponding characteristics of electromagnetic modeling algorithms;

[0077] Figure 2 It is a schematic flowchart of a method for modeling the cross-polarization scattering center of a target based on full-wave current data provided by Embodiment 1 of the present application;

[0078] Figure 3 It is a schematic diagram of the target model of the SLICY-like example of the embodiments of the present application;

[0079] Figure 4 It is a schematic diagram of the target area segmentation result of the embodiments of the present application;

[0080] Figure 5 It is a schematic diagram of the polarization decomposition result of the induced current when the incident angle is 0° in the embodiments of the present application;

[0081] Figure 6 Schematic diagram of the polarization decomposition result of the induced current when the azimuth angle is 45° in the embodiment of the present application;

[0082] Figure 7 Schematic diagram of the polarization decomposition result of the induced current when the azimuth angle is 90° in the embodiment of the present application;

[0083] Figure 8 Schematic diagram of the extraction result of the cross-polarization contribution region when the azimuth angle is 0° in the embodiment of the present application;

[0084] Figure 9 Schematic diagram of the extraction result of the cross-polarization contribution region when the azimuth angle is 45° in the embodiment of the present application;

[0085] Figure 10 Schematic diagram of the extraction result of the cross-polarization contribution region when the azimuth angle is 90° in the embodiment of the present application;

[0086] Figure 11 Schematic diagram of the reconstruction result of the cross-polarization contribution structure, the corresponding scattering center distribution and type annotation when the azimuth angle is 0° in the embodiment of the present application;

[0087] Figure 12 Schematic diagram of the reconstruction result of the cross-polarization contribution structure, the corresponding scattering center distribution and type annotation when the azimuth angle is 45° in the embodiment of the present application;

[0088] Figure 13 Schematic diagram of the reconstruction result of the cross-polarization contribution structure, the corresponding scattering center distribution and type annotation when the azimuth angle is 90° in the embodiment of the present application;

[0089] Figure 14 Schematic diagram of the RCS comparison between the cross-polarization scattering center model and the full-wave numerical method in the embodiment of the present application;

[0090] Figure 15 Schematic diagram of the TFR comparison between the cross-polarization scattering center model and the full-wave numerical method in the embodiment of the present application;

[0091] Figure 16 Schematic diagram of the HRRP comparison between the cross-polarization scattering center model and the full-wave numerical method in the embodiment of the present application;

[0092] Figure 17 Schematic diagram of the structure of a target cross-polarization scattering center modeling device based on full-wave current data provided in the embodiment of the present application. Detailed implementation manner

[0093] Embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present application, and should not be construed as limiting the present application.

[0094] The following describes a target cross-polarization scattering center modeling method and device based on full-wave current data in an embodiment of the present application with reference to the accompanying drawings.

[0095] Figure 2 A flow chart of a target cross-polarization scattering center modeling method based on full-wave current data provided in Example 1 of the present application.

[0096] like Figure 2 As shown, the target cross-polarization scattering center modeling method based on full-wave current data includes the following steps:

[0097] Step 201, dividing the geometric model of the target into mesh files;

[0098] In this embodiment, the geometric model of the target is segmented into a mesh file using software.

[0099] Step 202, based on the target grid file, using a full-wave numerical method to calculate the target surface induced current;

[0100] In this embodiment, the target grid file is imported into CAE software FEKO or other full-wave numerical method solvers to calculate the target surface induced current.

[0101] Step 203, performing orthogonal decomposition on the target surface induced current to obtain a current cross-polarization component;

[0102] In this embodiment, the current is orthogonally decomposed into: In this way, the current co-polarization component and the current cross-polarization component are obtained. Among them: p is the polarization mode of the incident wave, which is V or H,

[0103] Step 204, performing regional segmentation on the target grid file, and segmenting the current cross-polarization component based on the regional segmentation result to obtain cross-polarization current partitions;

[0104] In this embodiment, the target grid file is segmented by region, and the current is segmented based on this. According to the triangle grid vertex and index information, the center point coordinates and normal vectors of each grid are solved; traversing each triangle vertex index information, all pairs of adjacent triangles are extracted, and the determination method is that two triangles have two common vertices; solving the included angle between the normal vectors of each pair of adjacent triangles, when the included angle is less than the threshold, it is determined that the pair of triangles are coplanar, and when the included angle is greater than the threshold, it is determined that the common side of the pair of triangles is an edge structure, and all the edge structures of the target are extracted; extracting all the grids in each region based on the edge structure to complete the region segmentation; based on the region segmentation result, the current cross-polarization components of each region are obtained.

[0105] Step 205, adaptively extract the cross-polarization scattering contribution structure according to the sorting result of the current intensity of each region;

[0106] In this embodiment, for a metallic target, the electric field can be expressed by the Stratton-chu integral formula as:

[0107]

[0108] Replacing J p (r ′ ) in the above formula with the current cross-polarization component, the expression form of the cross-polarization scattering electric field can be obtained as follows:

[0109]

[0110] Substituting the current cross-polarization component of the target as a whole or the current cross-polarization component of certain regions into the corresponding cross-polarization scattering electric field expression, the cross-polarization scattering electric field of the target or the cross-polarization scattering electric field of certain regions can be solved and obtained.

[0111] In this embodiment, first, according to the average value of the current cross-polarization components of each region, intensity sorting is performed; regions are extracted one by one from strong to weak, and the cross-polarization scattering electric field of the extracted regions is solved, and after being converted into RCS, a relative error comparison is made with the cross-polarization scattering electric field of the target. The formula is as follows:

[0112]

[0113] Among them, RCS extracted is the RCS of the extracted region, and RCS total is the overall RCS of the target. When the relative error is greater than 1%, continue to extract the next region with stronger intensity, otherwise the extraction ends, and the cross-polarization scattering contribution structure is obtained.

[0114] Step 206: Determine the scattering center distribution mechanism based on the morphology of the cross-polarized component of the regional current, and determine the cross-polarized scattering center distribution by reconstructing the cross-polarized scattering contribution structure.

[0115] In this embodiment, the process of determining the corresponding scattering mechanism includes: determining the scattering center position. For striped currents, it is mainly the secondary scattering caused by the dihedral structure, and the scattering centers are distributed at the vertices of the common edges of the dihedral structure; for point-diffused currents, it is mainly the tertiary scattering caused by the trihedral structure, and the scattering centers are distributed at the common vertices of the trihedral structure; for line currents, it is mainly caused by edge diffraction, and the scattering centers are distributed at the vertices of the edges; for irregularly distributed currents, they are caused by multiple scattering sources, and each scattering source is still one of the above three cases and can be determined separately.

[0116] In this embodiment, the process of structure reconstruction includes: taking the extraction region as the reference, traversing to obtain all adjacent regions of this region, and deleting according to the incident direction and occlusion judgment, reconstructing structures such as dihedral angles and trihedral angles, and accurately positioning the vertices of the common edges of the dihedral structure or the common vertices of the trihedral structure.

[0117] Step 207: Establish a cross-polarized scattering center model of the target based on the cross-polarized scattering center distribution.

[0118] In this embodiment, based on the cross-polarized scattering center position distribution information obtained by extraction, the present invention uses the GTD scattering center model modified based on MBPE to parametrically characterize the cross-polarization, as shown in the following formula

[0119]

[0120] where N is the number of cross-polarized scattering centers, f is the incident frequency, f c is the center frequency, α is the frequency-dependent factor. For plane-plane secondary reflection, α is 1; for single-curved surface-plane secondary reflection and single-curved surface-single-curved surface secondary reflection, α is 0.5, k is the wave number, is the incident wave vector, r ′ is the scattering center position, ξ is the incident angle, which is a function of the pitch angle θ and the azimuth angle A(ξ) is the scattering center amplitude. Since the scattering center amplitude varies with the angle, based on MBPE, the amplitude-dependent function of cross-polarized scattering can be characterized by a fractional rational polynomial, as shown in the following formula:

[0121]

[0122] where P = [P 1 , P 2 ,..., P m and Q = [Q1 , Q 2 ,..., Q n-1 are the unknown parameters of the polynomial respectively, and m = n + 1. Compared with the ordinary polynomial, the above formula is easier to achieve the optimal estimation result with fewer parameters.

[0123] Among them, the parameter estimation method can choose the genetic algorithm (GA), or other parameter estimation methods can also be used. The objective function set during parameter estimation can be the minimum root mean square error of the RCS at multiple angles of the point frequency, or the maximum similarity of the time-frequency image (TFR). The minimum root mean square error is shown as follows

[0124]

[0125] Among them, RCS sc is the RCS obtained by solving the scattering center model, and RCS s is the RCS of the standard data (which can be the result of the full-wave numerical method), and Q is the number of data;

[0126] The maximum TFR similarity is shown as follows

[0127]

[0128] Among them, S s and S c are the time-frequency image data after the time-frequency transformation of the electric field of the scattering center model and the electric field of the standard data respectively. M×N is the dimension of the TFR data matrix, are the average values of the time-frequency image data of the scattering center model and the standard TFR data respectively.

[0129] Step 208: Based on the target grid file, calculate the RCS of the target using the full-wave numerical method, and obtain the cross-polarized scattering electric field of the target based on the cross-polarized scattering center model of the target. Determine whether the error between the RCS of the target and the cross-polarized scattering electric field of the target meets the requirements, and determine the cross-polarized scattering center model of the target.

[0130] In this embodiment, using the established scattering center model, obtain the cross-polarized scattering electric field of the target and verify it with the full-wave data. When the root mean square error of the RCS is less than 4 dB, or the TFR similarity is greater than 85%, the scattering center model is established. When the error does not meet the requirements, return to step six and re-determine the scattering center position and amplitude estimation.

[0131] In this embodiment, combine the above-mentioned cross-polarized electromagnetic scattering echo data of the target to calculate the SAR or ISAR image.

[0132] The target cross-polarization scattering center modeling method based on full-wave current data in the embodiment of the present application is oriented to the demand for fast and accurate calculation of cross-polarization electromagnetic scattering characteristics. The cross-polarization component of the current calculated by the full-wave numerical method is used to adaptively extract the cross-polarization contribution structure according to the sparsely sampled full-wave current, and then the cross-polarization scattering mechanism is analyzed and the position distribution of the scattering center is determined; the MBPE technology is used to estimate the parameters of the scattering center amplitude in the form of a polynomial to determine the scattering center amplitude, and finally the cross-polarization scattering center model of the target is established, which can accurately and quickly generate complex target cross-polarization electromagnetic characteristic data. This embodiment can be applied to the rapid simulation of radar polarization echoes and polarization radar remote sensing technology of complex electrically large-sized targets, thereby expanding the application field of scattering centers and solving the problems of insufficient understanding of the target cross-polarization scattering mechanism and unknown distribution of scattering centers.

[0133] This embodiment establishes a SLICY-like target CAD model such as Figure 3 As shown in the figure, the total length of the model is 1m. When performing full-wave solution on the target, the target is divided into a grid model with a grid size of 1 / 10 wavelength. At the same time, the grid model is used to perform regional segmentation. The segmentation results are shown in Figure 4 shown.

[0134] The full-wave numerical method is used to calculate the target surface current. The calculation parameters are set as follows: the incident polarization mode is V polarization, the pitch angle θ = 90°, and the target induced current polarization decomposition results for azimuth angles of 0°, 45°, and 90° are as follows: Figure 5 , Figure 6 and Figure 7 As shown in the figure, the left side is the current co-polarization component, i.e., VV current, and the right side is the current cross-polarization component, i.e., HV current. Then, the current cross-polarization component, i.e., HV current, is specifically studied. The results of adaptively extracting the cross-polarization contribution area based on the full-wave current with azimuth angles of 0°, 45°, and 90° are shown in the figure. Figure 8 , Figure 9 and Figure 10 As shown; the cross-polarization contribution structure reconstruction results and scattering center position and type annotation diagrams for azimuth angles of 0°, 45° and 90° are shown respectively Figure 11 , Figure 12 and Figure 13 shown.

[0135] After determining the scattering center position at different angles, this embodiment uses MBPE technology to estimate the scattering center amplitude. In the amplitude polynomial function, m=3 is set. The radar parameters are set as follows: the incident frequency is 8GHz, the elevation angle is 90°, the azimuth angle is 0-180°, and the HV polarization. After the scattering center model is established, the RCS result of the full-wave numerical method is compared. Figure 14As shown, the root mean square error of the RCS is 3.9 dB, and the calculation time of the scattering center model is only 0.02 seconds, which is much longer than the calculation time of the full-wave numerical method. The comparison with the TFR result of the full-wave numerical method is as follows Figure 15 shown, where Figure 15 The upper part is the full-wave numerical result, Figure 15 The lower part is the result of the scattering center model, and the TFR similarity is 89.5%.

[0136] At the same time, in this embodiment, the high-resolution one-dimensional range profile (HRRP) is also compared with the full-wave numerical method, which proves the frequency applicability of the scattering center model. The radar parameters are set as follows: incident frequency 7 - 9 GHz, interval 40 MHz, incident elevation angle 90°, azimuth angle 90°, HV polarization. The comparison between the scattering center model and the full-wave numerical result is as follows Figure 16 shown.

[0137] To implement the above embodiment, the present application also proposes a target cross-polarization scattering center modeling device based on full-wave current data.

[0138] Figure 17 FIG. is a schematic structural diagram of a target cross-polarization scattering center modeling device provided by an embodiment of the present application.

[0139] As Figure 17 shown, the target cross-polarization scattering center modeling device based on full-wave current data includes:[[]]

[0140] A full-wave current processing module, configured to divide the geometric model of the target into grid files, and based on the target grid files, calculate the induced current on the target surface using the full-wave numerical method, perform orthogonal decomposition on the induced current on the target surface to obtain the current cross-polarization component, and perform regional segmentation on the target grid files. Based on the regional segmentation result, segment the current cross-polarization component to obtain the cross-polarization current partition;

[0141] A cross-polarization contribution structure extraction module, configured to adaptively extract the cross-polarization scattering contribution structure according to the sorting result of the current intensity in each region, determine the scattering center distribution mechanism according to the morphology of the regional current cross-polarization component, and determine the cross-polarization scattering center distribution by reconstructing the cross-polarization scattering contribution structure;

[0142] A scattering center modeling module, configured to establish a cross-polarization scattering center model of the target based on the cross-polarization scattering center distribution, calculate the RCS of the target using the full-wave numerical method based on the target grid files, obtain the cross-polarization scattering electric field of the target based on the cross-polarization scattering center model of the target, and determine the cross-polarization scattering center model of the target when the error between the RCS of the target and the cross-polarization scattering electric field of the target meets the requirements.

[0143] It should be noted that the foregoing explanatory description of the embodiment of the target cross-polarization scattering center modeling method based on full-wave current data is also applicable to the target cross-polarization scattering center modeling device based on full-wave current data in this embodiment, and will not be elaborated here.

[0144] In the description of this specification, the description with reference to terms such as "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0145] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present application, the meaning of "a plurality" is at least two, such as two, three, etc., unless otherwise specifically defined.

[0146] Any process or method description shown in the flowchart or described in other ways herein can be understood to represent a module, segment, or part of code including one or more executable instructions for implementing a customized logic function or process. The scope of the preferred embodiments of the present application includes additional implementations, where the functions may be executed in a substantially simultaneous manner or in the reverse order according to the functions involved, rather than in the order shown or discussed, which should be understood by those skilled in the art to which the embodiments of the present application pertain.

[0147] The logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as a definite sequence list of executable instructions for implementing logical functions, and can be specifically implemented in any computer-readable medium for use by an instruction execution system, apparatus, or device (such as a computer-based system, a system including a processor, or other systems that can fetch and execute instructions from the instruction execution system, apparatus, or device), or used in combination with these instruction execution systems, apparatuses, or devices. For the purposes of this specification, a "computer-readable medium" can be any device that can contain, store, communicate, propagate, or transport a program for use by or in connection with an instruction execution system, apparatus, or device. More specific examples (non-exhaustive list) of computer-readable media include the following: an electrical connection portion having one or more wirings (electronic device), a portable computer diskette (magnetic device), a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber device, and a portable compact disc read-only memory (CDROM). Additionally, the computer-readable medium can even be paper or other suitable media on which the program can be printed, because the program can be obtained electronically, for example, by optically scanning the paper or other media, followed by editing, interpretation, or otherwise processing as appropriate, and then storing it in a computer memory.

[0148] It should be understood that the various parts of the present application can be implemented by hardware, software, firmware, or a combination thereof. In the above-described embodiments, multiple steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented in hardware, as in another embodiment, any one or a combination of the following techniques well known in the art can be used: discrete logic circuits having logic gate circuits for implementing logical functions on data signals, application specific integrated circuits having appropriate combinational logic gate circuits, programmable gate arrays (PGAs), field programmable gate arrays (FPGAs), etc.

[0149] Those of ordinary skill in the art of this technology can understand that all or part of the steps carried by the method of implementing the above embodiments can be completed by instructing relevant hardware through a program, and the program can be stored in a computer-readable storage medium. When the program is executed, it includes one or a combination of the steps of the method embodiment.

[0150] In addition, each functional unit in various embodiments of the present application may be integrated into one processing module, or each unit may exist physically alone, or two or more units may be integrated into one module. The above-mentioned integrated module may be implemented in the form of hardware or in the form of a software functional module. When the integrated module is implemented in the form of a software functional module and sold or used as an independent product, it may also be stored in a computer-readable storage medium.

[0151] The above-mentioned storage medium may be a read-only memory, a magnetic disk, an optical disc, etc. Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present application. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present application.

Claims

1. A target cross-polarization scattering center modeling method based on full-wave current data, characterized in that: include: Divide the target's geometric model into mesh files; Based on the target grid file, the full-wave numerical method is used to calculate the induced current on the target surface; orthogonally decomposing the target surface induced current to obtain a current cross-polarization component; Performing regional segmentation on the target grid file, and segmenting the current cross-polarization component based on the regional segmentation result to obtain cross-polarization current partitions; According to the ranking results of the current intensity in each region, the cross-polarization scattering contribution structure is adaptively extracted; The scattering center distribution mechanism is determined based on the morphology of the cross-polarization component of the regional current, and the cross-polarization scattering center distribution is determined by reconstructing the cross-polarization scattering contribution structure; Based on the cross-polarization scattering center distribution, establishing a cross-polarization scattering center model of the target; Based on the target grid file, the RCS of the target is calculated using a full-wave numerical method, and the cross-polarization scattering electric field of the target is obtained based on the cross-polarization scattering center model of the target, it is judged that the error between the RCS of the target and the cross-polarization scattering electric field of the target meets the requirement, and the cross-polarization scattering center model of the target is determined.

2. The method according to claim 1, characterized in that The target surface induced current is orthogonally decomposed to obtain the current cross-polarization component, which is expressed as: in, Among them, J p is the induced current excited by the incident light in p-polarization mode, J Vp is the V polarized emission component of the induced current, J Hp is the H-polarized emission component of the induced current, is the V polarization vector, is the H polarization vector, J p (r′) is the induced current at the excitation point r′, p is the polarization mode of the incident wave, which is V or H, 3. The method according to claim 1, characterized in that Performing region segmentation on the target grid file includes: According to the triangle mesh vertex and index information, solve the center point coordinates and normal vector of each mesh; Traverse the vertex index information of each triangle and extract all co-side triangle pairs, wherein the co-side triangle pairs are determined in the manner that two triangles have two common vertices; Solve the angle between the normal vectors of each pair of co-lateral triangles. When the angle is less than the threshold, the pair of triangles is judged to be coplanar. When the angle is greater than the threshold, the common side of the pair of triangles is judged to be an edge structure, and all the edge structures of the target are extracted; Extract all grids in each area based on the edge structure to complete the area segmentation; The method of dividing the current cross-polarization component based on the regional division result to obtain the cross-polarization current partition includes: Based on the regional segmentation results, the current cross-polarization component of each region is obtained, and the cross-polarization current partition is obtained.

4. The method according to claim 1, characterized in that The adaptive extraction of the cross-polarization scattering contribution structure according to the sorting results of the current intensity of each region includes: The electric field representation of the target is determined by the Stratton-Chu integral formula, and the induced current at the excitation point in the electric field representation of the target is replaced by the cross-polarization component of the current to obtain the expression of the cross-polarization scattered electric field; Substitute the cross-polarization component of the target current into the expression of the cross-polarization scattered electric field to obtain the cross-polarization scattered electric field of the target; The intensity is sorted according to the average value of the cross-polarization component of the current in each area; Based on the sorting results, the regions are extracted from strong to weak. After each extraction, the current cross-polarization component of the extracted region is substituted into the expression of the cross-polarization scattered electric field to obtain the cross-polarization scattered electric field of the extracted region. The cross-polarization scattered electric field of the extracted region is converted into RCS and the relative error is compared with the target cross-polarization scattered electric field. When the relative error meets the requirements, the extraction is completed and the cross-polarization scattering contribution structure is obtained.

5. The method according to claim 4, characterized in that The electric field of the target is expressed as: Where j is the imaginary unit, k is the wave number, η0 is the free space impedance, is the incident electric field, r is the distance from the radar to the target, is the incident wave vector, s′ is the integral term of the area, and S′ is the area of ​​the area; The induced current J at the excitation point r′ p (r′) are replaced by the current cross-polarization component J HV (r′), J VH (r′), the expression of the cross-polarization scattered electric field is: The relative error is: Among them, RCS extracted is the RCS of the extracted area, RCS total The RCS for the target.

6. The method according to claim 4, characterized in that The method of determining the distribution mechanism of the scattering center according to the form of the cross-polarization component of the regional current includes: For the stripe current, it is assumed to be secondary scattering caused by the dihedral structure, and its scattering center is determined to be distributed at the vertices of the common edges of the dihedral structure; For the point diffusion current, it is assumed to be the triple scattering caused by the trihedral structure, and its scattering center is determined to be distributed at the common vertex of the trihedral structure; For the set line current, it is assumed to be caused by edge diffraction, and its scattering center is determined to be distributed at the vertex of the edge; For irregularly distributed current, determine the scattering centers of stripe current, point diffusion current and line current; The method of determining the cross-polarization scattering center distribution by reconstructing the cross-polarization scattering contribution structure includes: Taking the extraction area as a reference, traverse all adjacent areas of the extraction area, delete them according to the incident direction and occlusion judgment, reconstruct the dihedral angle and trihedral angle, and locate the vertices of the common edges of the dihedral angle structure or the common vertices of the trihedral angle structure; During the traversal, the cross-polarization scattering center distribution is determined based on the scattering center distribution mechanism.

7. The method according to claim 1, characterized in that The establishing of a cross-polarization scattering center model of the target based on the cross-polarization scattering center distribution includes: Based on the cross-polarization scattering center distribution, a GTD scattering center model based on MBPE correction is used to parameterize the cross-polarization. When performing parametric characterization, the objective function of parameter estimation is set to minimize the root mean square error of the electric frequency multi-angle RCS or maximize the similarity of the time-frequency image TFR, and the unknown parameters are estimated.

8. The method according to claim 7, characterized in that Based on the cross-polarization scattering center distribution, the cross-polarization is parameterized using the GTD scattering center model corrected based on MBPE, which is expressed as: Where N is the number of cross-polarization scattering centers, f is the incident frequency, and f c is the center frequency, α is the frequency dependence factor, k is the wave number, is the incident wave vector, r′ n is the position vector of the nth scattering center, ξ is the incident angle, A(ξ) is the scattering center amplitude, and based on MBPE, the amplitude dependence function of cross-polarization scattering is characterized by fractional rational polynomials, which is expressed as: Where P = [P1, P2, ..., P m ],Q=[Q1,Q2,...,Q n-1 ] are the unknown parameters of the polynomial, m=n+1; The root mean square error is expressed as: Among them, RCS sc (i) is the RCS obtained by solving the cross-polarization scattering center model, RCS s is the RCS of standard data, Q is the number of data; TFR similarity is expressed as: Among them, s s 、s c are the time-frequency image data after time-frequency transformation of the cross-polarization scattering center model electric field and the standard data electric field, M×N is the TFR data matrix dimension, They are the average of the time-frequency image data of the cross-polarization scattering center model and the standard TFR data, respectively.

9. The method according to claim 8, characterized in that Determining whether an error between an RCS of the target and a cross-polarization scattered electric field of the target meets a requirement includes: The error is set to be a root mean square error or TFR similarity, and when the root mean square error is less than a first preset threshold or the TFR similarity is greater than a second preset threshold, it is judged that the error meets the requirement; The method further comprises: When the error does not meet the requirements, the cross-polarization scattering contribution structure is reconstructed, the second cross-polarization scattering center distribution is determined, and the second cross-polarization scattering center model of the target is constructed, and the second cross-polarization scattering electric field of the target is obtained based on the second cross-polarization scattering center model of the target, and it is determined that the error between the RCS of the target and the second cross-polarization scattering electric field of the target meets the requirements, and the cross-polarization scattering center model of the target is determined.

10. A target cross-polarization scattering center modeling device based on full-wave current data, characterized in that: include: A full-wave current processing module is used to divide the geometric model of the target into grid files, and based on the target grid file, use the full-wave numerical method to calculate the target surface induced current, and perform orthogonal decomposition on the target surface induced current to obtain the current cross-polarization component, and perform regional segmentation on the target grid file, and divide the current cross-polarization component based on the regional segmentation result to obtain the cross-polarization current partition; The cross-polarization contribution structure extraction module is used to adaptively extract the cross-polarization scattering contribution structure according to the sorting results of the current intensity in each region, determine the scattering center distribution mechanism according to the form of the cross-polarization component of the regional current, and determine the cross-polarization scattering center distribution by reconstructing the cross-polarization scattering contribution structure; A scattering center modeling module is used to establish a cross-polarization scattering center model of the target based on the cross-polarization scattering center distribution, calculate the RCS of the target using a full-wave numerical method based on the target grid file, obtain the cross-polarization scattering electric field of the target based on the cross-polarization scattering center model of the target, determine whether the error between the RCS of the target and the cross-polarization scattering electric field of the target meets the requirements, and determine the cross-polarization scattering center model of the target.

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