27 results about "Em scattering" patented technology

The present application belongs to the technical field of stealth design of aircraft shape and structure, and discloses a surface wave electromagnetic scattering characteristic quantitative analysis method based on a two-port transmission model. The surface wave electromagnetic scattering characteristic quantitative analysis method based on the two-port surface wave transmission model has an electromagnetic discontinuous structure. By loading the electromagnetic discontinuous structure, the scattering parameters of the port network are monitored, and by changing the structural parameters of the electromagnetic discontinuous structure, the influence of the structural parameters of the electromagnetic discontinuous structure on the surface wave scattering characteristic is quantitatively studied. The surface wave electromagnetic scattering characteristic quantitative analysis method can separate the spatial electromagnetic scattering component when the spatial electromagnetic wave is directly irradiated, and can analyze the electromagnetic scattering characteristic of the surface wave in the discontinuous electromagnetic structure alone, thereby laying a foundation for studying the surface wave electromagnetic scattering characteristic of the electromagnetic discontinuous structure such as a curved surface, a gap and a step, and providing guidance for the stealth design of the aircraft shape and structure.

This invention belongs to the field of computational electromagnetics numerical simulation and provides a simulation method for electromagnetic scattering of thin-coated targets based on Schur complement preconditions. First, for the IBC scattering target to be solved, equivalent surface current and equivalent surface magnetic current are introduced as independent unknowns. The electromagnetic scattering solution equation is established using SDIE and then discretized. Next, the impedance matrix is ​​decomposed into near-field and far-field matrices using an octree structure. For the near-field matrix, key operator sub-blocks are explicitly assembled and extracted. Then, approximate operators in block diagonal form and Schur complement operators are constructed and approximately inverted. Simultaneously, the diagonal product of intermediate blocks is pre-calculated and stored based on the approximate operators. Finally, the constructed preconditions are applied to the GMRES iterative solver. When the iteration error reaches the preset convergence criterion, the current and magnetic current distributions on the target surface are output. Further calculations of radiation characteristic parameters such as the target's radar cross section are then performed, achieving low-cost, high-efficiency, and easily parallelizable electromagnetic simulation solutions.

This invention discloses a terahertz-band foreign object detection radar system and method for airport runways. The system includes: a transmitting module for generating and transmitting a 240 GHz frequency-modulated continuous wave detection signal; a receiving module for receiving the echo signal and down-converting it to an intermediate frequency signal; a turntable system for driving the transmitting and receiving modules to rotate synchronously for azimuth scanning; and a digital control and processing module for generating baseband waveforms, acquiring angle information and intermediate frequency signals, and performing data processing to detect and locate foreign objects. This invention utilizes the physical law that the radar cross-section of a target is inversely proportional to the fourth power of its wavelength, fundamentally enhancing the electromagnetic scattering response of small targets and achieving high-sensitivity detection of millimeter-sized metal debris and non-metallic foreign objects, providing a reliable technical solution for foreign object detection on airport runways.

The application belongs to the technical field of electromagnetic modeling of targets in layered media, and specifically provides a plane multilayer medium electromagnetic scattering modeling method based on layered medium Green function, which is used to solve the problems of large number of unknown quantities and low calculation efficiency when analyzing the electromagnetic scattering characteristics of targets in layered media; first, the medium target in the plane multilayer medium is meshed; then, the layered medium Green function is calculated based on the space list and interpolation method, and the matrix equation of the target current and magnetic current is constructed by solving the surface integral equation of the target by using the method of moments; finally, the improved stacked non-diagonal low-rank matrix is used to solve the matrix equation to calculate the target scattering field. The application adopts a direct solving calculation method, effectively solves the problem of ill-conditioned matrix difficult to converge in the conventional iterative method, especially for the multi-port excitation problem, without the need for repeated calculation, improving the solving efficiency of large-scale problems and reducing the consumption of calculation resources.

This invention relates to the field of electromagnetic simulation technology, and in particular to a PINN method integrated with dielectric electromagnetic boundary conditions, used to solve electromagnetic field simulation problems involving multiple dielectrics, high contrast, and fine geometries in nanophotonics and optoelectronic device design. By explicitly embedding the frequency-domain Maxwell's equations, external boundary conditions, and dielectric interface continuity conditions into the PINN loss function system, a multi-objective optimization framework is constructed, including partial differential equation residuals, boundary condition residuals, and interface physical constraint residuals. Combined with a multi-subdomain network design strategy and dynamic sampling methods, accurate modeling of complex dielectric interfaces and high-contrast electromagnetic fields is achieved. Compared with traditional numerical methods, this invention significantly improves simulation efficiency and accuracy, and supports multi-scale coupled solutions using PINN and traditional mesh methods, making it suitable for fields such as micro / nano optical device design and electromagnetic scattering analysis.

The application provides a kind of physical prior driven three-dimensional electromagnetic scattering calculation method of deep learning under the condition that three-dimensional scatterer shape and electric parameter are not completely known, can utilize multi-angle observation data, realize the solution to three-dimensional scattering characteristics under the condition that scatterer shape and electromagnetic parameter are not completely known.Method first carries out pre-processing to the data of known part of scatterer, then uses neural network to predict the multi-angle internal total field of complete three-dimensional scatterer, based on the predicted multi-angle internal total field of complete three-dimensional scatterer, uses moment method to calculate the scattering field generated by three-dimensional scatterer under the irradiation of different angle incident wave.The application can use multi-angle scattering field (observation / measurement) data and known physical prior information to predict the scattering characteristics of three-dimensional scatterer whose shape and electric parameter are not completely known.

This invention provides a method for calculating the electromagnetic scattering SBR of a distributed material mapping target, belonging to the field of electromagnetic simulation technology. The method first determines a distributed material mapping scheme; secondly, it uses the periodic moment method to calculate the S-parameters of different materials used in the distributed material mapping scheme at different incident angles; then, it uses the bouncing ray method to perform initial ray tracing of the target to obtain reusable path parameter information; subsequently, based on the distributed material mapping scheme, it uses bilinear interpolation and pre-calculated S-parameters to calculate the required S-parameters, and combines this with the corresponding reusable path parameter information to solve for the reflection field vector; finally, it uses the reflection field vector to solve for the total scattered electric field, thereby calculating the target's scattering cross-section. This invention decouples time-consuming geometric ray tracing from material electromagnetic calculations, eliminating the need for repeated geometric ray tracing when processing distributed material layout optimization or modification designs, significantly improving the computational efficiency of the electromagnetic scattering characteristics of complex stealth targets.

This invention provides an integrated and accurate simulation method for electromagnetic scattering of partially rotating targets, comprising: modeling and setting system parameters; dividing the target into relatively stationary sub-regions, rotating sub-regions, and linked sub-regions, and establishing a rotationally symmetric equivalent surface to completely enclose the rotating sub-domains; establishing a global coordinate system and a local coordinate system; using a consistent mesh in the global coordinate system as the outer mesh, and independently meshing the local coordinate system as the inner mesh, and defining the inner and outer basis functions accordingly; calculating the self-acting operator, equivalent operator, coefficient solving operator, and interaction operator of the equation to be solved; updating the coordinate system rotation operator between the global and local coordinate systems, establishing and solving the equation to be solved for the partially rotating conductor target at the current moment, and then calculating the far-field scattering field at the current moment from the scattering electromagnetic current coefficient vector; repeating the first two steps until the calculation of the far-field scattering field at different sampling time points throughout the entire rotation cycle is completed. This method has a fast modeling speed.

The application discloses a kind of electromagnetic scattering characteristic simulation detection method, device, equipment, medium and product, by the radar echo data of standard target and the damage target to be measured is converted into time domain scattering data, and the damaged part in the time domain scattering data of damage target to be measured is replaced with the time domain scattering data of standard target, and then the overall scattering characteristic of damage target to be measured after simulation maintenance is obtained.Time domain data is used to replace damage part data, the result signal obtained has high continuity, few sections, and the small amount of discontinuous parts that appear is easy to recover, and the accuracy of evaluating the overall scattering characteristic of simulation maintenance damaged component is high through the data;Further, the overall scattering characteristic is obtained by data replacement to simulate maintenance to damage target to be measured, the local maintenance effect of damage target can be quickly estimated, maintenance reference is provided for maintenance personnel, and the number of repeated tests and test time of target are reduced.

This invention relates to the field of high-frequency electromagnetic calculation technology using physical optics, specifically to a method for reverse ray tracing in preprocessing of surface elements. When reading the triangular mesh information of the model, this invention calculates the normal vector, center coordinates, and axial bounding box (AABB) of each triangular surface element. Triangular surface elements whose dot product of the normal vector and the plane wave incident direction is less than 0 are designated as potential illuminated surfaces and included in the potential illuminated area set. Then, a secondary illumination judgment is performed on the triangular surface elements in each potential illuminated area to obtain the final set of effective illuminated surfaces. Finally, the scattering contributions of each effective illuminated surface element are summed to obtain the total scattering field of the target, and the radar cross section (RCS) is then calculated. This invention systematically solves the core contradictions of existing technologies—insufficient accuracy of the normal vector dot product, two-dimensional approximation of projection clipping, and low efficiency of traditional reverse ray tracing—through an integrated design; it provides a novel technical solution for the electromagnetic scattering characteristics analysis of electrically large targets.

The application discloses a kind of electromagnetic scattering data determination method and device of test target, belong to target electromagnetic scattering characteristic test field.The method comprises: constructing semi-empirical model of test target;First scattering geometric parameter known to test target and electromagnetic scattering characteristic data corresponding to first scattering geometric parameter are input into semi-empirical model, and the model parameter of semi-empirical model is obtained;Second scattering geometric parameter known to test target is input into semi-empirical model with determined model parameter, and the electromagnetic scattering characteristic data corresponding to second scattering geometric parameter is obtained;Wherein, the bistatic angle corresponding to second scattering geometric parameter is greater than the bistatic angle corresponding to first scattering geometric parameter.The present application can improve the accuracy and reliability of large bistatic angle test on rough ground (such as land, cement ground).

The present application belongs to the medical imaging technical field, especially to a kind of electromagnetic sparse imaging method of metal foreign matter in human body fusing background knowledge, the present application includes the following steps: construct the electromagnetic scattering model of human tissue without metal foreign matter: construct the electromagnetic scattering model of human tissue after embedding metal foreign matter: fuse background knowledge, establish difference scattering model to extract metal foreign matter response: define contrast source and construct inversion model based on joint sparse regularization: solve inversion model and reconstruct metal foreign matter image;The present application proposes a modeling method fusing background prior knowledge, the proposed method can utilize the prior knowledge of human tissue, which helps to improve the problem of ill-conditioned, in order to further overcome inverse ill-conditioned, use joint sparse regularization technique to constrain the solving process of electromagnetic inverse problem, further improve the positioning accuracy of metal foreign matter, improve imaging accuracy, propose a kind of joint sparse regularization method, which can enhance the accuracy of imaging.

The application discloses a SAR image expansion method based on principal component analysis and a multi-task Gaussian process regression model, and comprises the following steps: constructing a two-dimensional feature matrix of a sample SAR image in terms of an azimuth angle and a pixel gray value; mapping a high-dimensional pixel space of the extracted image to a low-dimensional feature subspace by using principal component analysis, and extracting principal component coefficients representing electromagnetic scattering characteristics of a target; introducing a multi-input multi-output Gaussian process regression model framework, combining a constant mean function and a spectral mixed kernel function, and constructing a proxy model capable of representing scattering characteristic evolution rules; constructing internal correlations between different principal components, rapidly predicting a coefficient vector of an unknown azimuth angle, and reconstructing a SAR image of the unknown azimuth angle by means of PCA inverse transformation. The application integrates the dimension reduction advantage of PCA and the rapid prediction capability of the multi-task Gaussian process regression, guarantees the accuracy of the generated image, and significantly reduces the calculation complexity and running time.

The application discloses a method for analyzing electromagnetic scattering problems of thin dielectric targets with uncertain shape, which is based on the method of moments of integral equation, and the geometric shape of a three-dimensional target is flexibly described by using a small number of control points through NURBS surface modeling, and the three-dimensional coordinates of the control points are set as random variables, so that the geometric shape uncertainty of the target is accurately quantified. By constructing a conformal triangular mesh to discretize the NURBS surface and establishing a method of moments solution model based on the RWG basis function, the random variables are introduced into the impedance matrix and the excitation vector through the basis function, so that the geometric and material property uncertainty of the target is directly reflected in the electromagnetic scattering control equation. The electromagnetic scattering characteristics of the thin dielectric material target under the influence of uncertainty are quantitatively analyzed by combining the perturbation method, and the sensitivity of the scattering characteristics to small-scale geometric and material perturbation is evaluated.

The application provides a method and system for calculating the electromagnetic scattering coefficient of a sea surface under the action of a two-dimensional flow field, comprising the following steps: step 1, setting a sea surface area to be observed, setting flow field and wind field data, and setting radar parameters; step 2, setting relevant parameters in a wave-current interaction model, and establishing a wave action spectrum conservation equation according to the wave-current interaction model; step 3, solving the wave action spectrum conservation equation by using a ray tracing method to obtain a new wave action spectrum of a wave train after the wave train is modulated by the flow field; step 4, converting the new wave action spectrum obtained in step 3 into a wave height spectrum, and calculating sea level related information including the root mean square height and the local incidence angle of each point by using the wave height spectrum; and step 5, inputting the calculated sea surface information and the set radar parameters into an IEM electromagnetic scattering model to calculate the modulated backscattering coefficient. The flow field modulation model based on the IEM model can effectively calculate the electromagnetic scattering of the sea surface under the modulation of the two-dimensional flow field.

This invention discloses an over-the-horizon radar sea clutter propagation and scattering simulation system, belonging to the field of simulation technology. The system adopts a heterogeneous parallel computing architecture, including a radio wave propagation modeling module, a propagation-scattering bidirectional coupling module, and a sea surface electromagnetic scattering modeling module. The output of the radio wave propagation modeling module is connected to the input of the propagation-scattering bidirectional coupling module, the output of the propagation-scattering bidirectional coupling module is connected to the input of the sea surface electromagnetic scattering modeling module, and the output of the sea surface electromagnetic scattering modeling module is connected to the input of the propagation-scattering bidirectional coupling module. Using this system, through propagation-scattering bidirectional coupling, nonlinear time-varying sea surface generation, and a parallel architecture, this invention achieves physically self-consistent, high-fidelity, and high-efficiency sea clutter simulation, accurately reproducing the characteristics of all sea states, and providing key support for over-the-horizon radar performance evaluation, clutter suppression, and atmospheric waveguide inversion.

The application provides a metal scatterer electromagnetic scattering analysis method based on an electric field integral equation, triangular surface patch units are used to discretize a target surface, and RWG base functions are defined to expand and approximate surface currents; the expanded and approximated surface current is substituted into the electric field integral equation, the equation is tested by using a RWG-based test function, a discrete electric field integral equation matrix system is obtained; a Gram matrix corresponding to the RWG base function is constructed, according to a matrix function theory, Chebyshev polynomial approximation expansion suitable for a scalar inverse square root is extended to Chebyshev polynomial approximation expansion suitable for a matrix inverse square root, and numerical calculation of the Gram matrix inverse square root is realized; the Gram matrix inverse square root is used to precondition the discrete electric field integral equation matrix system, a correlation between a solution vector of a preconditioned matrix equation system and a solution vector of an original matrix equation system is established, and a spatial scattering field of the metal scatterer is obtained. The application improves the electromagnetic scattering analysis efficiency of the metal scatterer.

This invention discloses a method for calculating the single-station multi-angle RCS of a target based on a multilayer perceptron, belonging to the field of electromagnetic scattering modeling. The method includes: acquiring the real-time elevation and azimuth angles of the target; inputting the elevation and azimuth angles into two pre-trained multilayer perceptron models to obtain nonlinear mapping relationships with the real and imaginary parts of the far-field scattered electric field based on the elevation and azimuth angles, respectively, and outputting the corresponding far-field scattered electric field estimates in real time; and calculating the single-station RCS value of the target at the corresponding angle based on the far-field scattered electric field estimates. This scheme combines high accuracy and high efficiency and can be widely applied in target detection and electromagnetic compatibility fields.

This invention discloses a method for predicting attribute scattering center parameters based on automatic radar component segmentation and a phase-coordinated network. First, the method utilizes a PointNet++ network with multi-scale grouping and normal vector features to automatically segment complex target point clouds into basic geometric components, and achieves physical diversity of ray data based on the segmentation results. Second, a phase-coordinated network is constructed, endowing the network with electromagnetic interference sensing capabilities through explicit phase encoding. Distributed covariance pooling is used to accurately capture the spatial topological shape distribution of rays. A multi-task decoupled prediction head and a physically constrained sensing loss function are used to achieve high-precision prediction of the attribute scattering center position, field value, amplitude, frequency dependence factor, and length distribution parameters. This invention significantly improves the modeling accuracy and physical consistency of the electromagnetic scattering characteristics of complex targets, and its inference speed is faster than the traditional ESPRIT algorithm, making it suitable for real-time radar target recognition and RCS reconstruction.

A simulation, prediction and measurement method of aircraft shock wave field, which analyzes the spectral characteristics of aircraft shock wave field, uses acoustic horn antenna to simulate the physical characteristics of shock wave field, and predicts the radar cross section (RCS) under the Bragg matching condition, uses high-power radar to detect at the Bragg matching frequency, obtains characteristic quantities such as power spectrum, RCS and frequency shift, can directly reflect the physical scattering process of atmospheric acoustic field, is easy to understand, provides a principle verification method for the outflow field detection of supersonic aircraft, and is suitable for electromagnetic scattering detection of atmospheric flow field.

The application relates to a target RCS prediction method based on a Gaussian process regression and a two-dimensional agent model, which comprises the following steps: a three-dimensional rectangular block is established, and parameters are set; a data set is acquired; a composite covariance function is constructed, and a Newton gradient method is used to optimize and solve hyperparameters; a two-dimensional agent model is constructed according to the optimized hyperparameters, a covariance vector and a covariance matrix of the agent model are calculated, and a prediction result is obtained; and the prediction result is evaluated according to evaluation indexes. The two-dimensional agent model has good performance; through training of training data, a corresponding relationship between input and output is found, and a test set is used to realize a prediction function; overall, time consumed is obviously less than that of a traditional electromagnetic scattering algorithm, and calculation cost is saved; the method is not only suitable for a radar signal analysis field, but also suitable for remote sensing research, geophysical science and the like, and analysis cost is low.

This application relates to the field of bistatic polarimetric radar technology, and particularly to a simulation method and system for bistatic fully polarimetric radar ellipsoidal particle target imaging based on electromagnetic properties. The method includes: setting radar parameters and ellipsoidal particle target parameters; calculating the far-field scattering coefficients of the ellipsoidal particles at different frequencies and target rotation angles under different polarization channels based on the radar parameters and ellipsoidal particle target parameters and utilizing the electromagnetic scattering characteristics of the ellipsoidal particles; simulating the received echoes of the corresponding bistatic fully polarimetric radar system based on the far-field scattering coefficients under different polarization channels, and extracting the scattering coefficients of noisy targets from the received echoes; and performing imaging processing on the scattering coefficients of each noisy target based on the bistatic inverse synthetic aperture radar (ISAR) turntable imaging principle to obtain a bistatic fully polarimetric radar image of the ellipsoidal particle target. This application simplifies the simulation process, fully considers the actual noise impact, and improves imaging efficiency.

The application discloses an icosahedral corner reflector ASC forward modeling method, device and product, relates to the field of radio detection, and is used for realizing efficient and accurate characterization of electromagnetic scattering characteristics of a complex calibration body under sparse angles or a dynamic environment. The application automatically peels off and reconstructs a physical scattering component with clear physical meaning from unordered three-dimensional discrete digital grid data, solves a basic scattering response under high-frequency approximation in real time, fuses accurate geometric phase center calculation and an environment perception correction model, quantifies disturbance introduced by a dynamic environment, and finally solves an ASC parameter set in a forward direction. The parameter set generated in real time by the application can reproduce phase interference fringes of the icosahedral corner reflector under a dynamic viewing angle and RCS attenuation characteristics caused by non-ideal structural deformation with high fidelity, and provides parameterized model support conforming to electromagnetic physical laws for radar system calibration and SAR image simulation.

The application discloses a kind of based on wideband radar unmanned aerial vehicle cluster extended target detection tracking method and system, specifically is: first set unmanned aerial vehicle cluster scene, calculate target electromagnetic scattering characteristics, unmanned aerial vehicle cluster is equivalent to by multiple scattering center Extended target is generated cluster extended target wideband radar echo;Then calibration and compensation are carried out to wideband observation data, if there is no candidate target, then wait for the data input of next frame;When target distance information is extracted on distance dimension, angle estimation is carried out using multi-beam coherent fitting method, and the distance-angle detection result of cluster target is output;Finally, based on joint information, data association is carried out, the spatial shape parameter of cluster target is introduced into tracking model as state quantity, and target motion state is predicted and updated together, dynamic regulation of candidate observation range is realized.The application has high calculation efficiency, model is simple, and the tracking precision and stability of dynamic unmanned aerial vehicle cluster target detection and tracking are improved.