287 results about "Radar cross-section" patented technology

The invention discloses an airborne radar identification method based on multi-scale signal decomposition and depth feature fusion, belongs to the technical field of radar target identification, is used for unmanned aerial vehicle radar target identification, and comprises the following steps: decomposing an original dynamic radar cross section signal into a plurality of intrinsic mode components by adopting an adaptive noise complete set empirical mode decomposition method; self-adaptive wavelet soft threshold denoising is carried out on all the components in a unified mode so as to improve the signal-to-noise ratio and suppress background interference; effective components are screened out by calculating correlation coefficients of all intrinsic mode components and original signals, a radar cross section signal sequence after noise reduction is reconstructed, and multilevel feature fusion is carried out; and inputting the feature vector into a stacked auto-encoder deep neural network classification model, and introducing a particle swarm optimization algorithm to optimize the classification model. According to the method, the signal-to-noise ratio of the signal and the recognition accuracy of the classification model in a low signal-to-noise ratio environment are remarkably improved, and high-precision recognition and classification of different types of radar cross section targets are realized.

The invention discloses a high-sensitivity metal micro-strain sensor label and a detection method thereof, which are applied to the field of nondestructive testing and the field of structural health monitoring. The problems that an existing tag antenna is low in strain detection sensitivity and difficult in micro-strain detection are solved. The high-sensitivity metal micro-strain RFID sensing tag is attached to the surface of a component, when the tag deforms, the impedance change of the tag is Zsened, and the radar cross section changes accordingly; the reader can remotely monitor antenna parameters according to the change of the RCS0, the RCS1 and the intensity while communicating with the tag, so that the change of the intensity RSSI of an echo signal is deduced, and the deformation of the tag is indirectly known; when the impedance of the tag antenna changes, the resonant frequency of the tag changes accordingly, and the deformation information of the tag can be indirectly obtained by analyzing the deviation of the resonant frequency.

The invention belongs to the technical field of superconducting wires, and relates to a niobium-tin composite superconducting wire and a preparation method thereof. The invention provides a Nb3Sn composite superconducting wire. The Nb3Sn composite superconducting wire sequentially comprises an Nb3Sn superconducting wire core, a barrier layer, a stable layer, a transition layer, a substrate layer and a functional layer from inside to outside, the transition layer is formed by mixing copper and a dielectric polymer, and the copper content is continuously decreased in a gradient manner from inside to outside; the substrate layer is the dielectric polymer; the functional layer is a plurality of protruding metal microstructures. According to the invention, the functional layer with the broadband electromagnetic stealth function is integrated on the basis of the Nb3Sn superconducting wire rod, so that the radar cross section is obviously reduced while the Nb3Sn superconducting wire rod bears high-density superconducting current and generates a strong magnetic field, and the technical problem that a high-field superconducting magnet system is easy to detect in an electromagnetic environment is solved.

An unmanned aerial vehicle (UAV) identification method based on blind source separation and deep learning is disclosed, in the method, firstly, the one-dimensional radar cross section millimeter wave data set of the UAV is acquired, and the mixed signal is obtained by mixing, and the improved FastICA algorithm is used to separate it. Secondly, the separated signal is converted into a two-dimensional image by data transformation, and the two-dimensional image is augmented, the obtained data set is divided into training set, validation set and test set. Thirdly, establish a UAV classification model based on Improved ResNet18 and train this model on the training set to achieve UAV classification. In the present invention, the training time of the network is not greatly increased while the network identification accuracy is improved, so that it can well complete the UAV type identification, and the design is more reasonable and effective.

Wireless devices are commonly carried in fabric-based apparel. Printing metamaterial structures on fabric substrates allows for the ability to create fabric metamaterial layers. A reconfigurable RF based fabric system simply by physically removing or adding different fabric-based metamaterial layers to different regions of the apparel. The fabric-based metamaterial can be used in various filtering applications where the control of phase, reflection angle, refraction angle, polarization, absorption, and transmission of the impinged electromagnetic wave can all be manipulated. Additionally, sophisticated metamaterial systems can be created by combining different metamaterial layers separated above each other. A controllable absorber metamaterial system can be made consisting of two layers. The first layer an electronically controllable that can controllably change between a band-pass and band-reject filter in a relevant frequency band and a second absorptive layer. Vehicles with adjustable metamaterial absorber systems, integrated on the outside or inside of the RF transparent fuselage, have the ability to control their radar cross section dynamically for the purposes of evading detection or spoofing their size by looking larger or similar to vehicles of different radar cross section.

The invention relates to a phased array tracking method based on four-dimensional joint weighted dynamic pre-switching, and belongs to the technical field of phased array communication. The method comprises the following steps: updating space-time correlation parameters to a target historical motion track database, and generating a target state prediction value based on a UKF prediction method; starting a four-dimensional joint gradient weighting program, carrying out linear phase interpolation of a time delay dimension, and generating a control signal with a continuous phase; solving a mutual coupling matrix, establishing a cross-array-plane phase mapping model based on cubic spline interpolation, and compensating a residual phase error; according to the real-time radar cross section, the number of effective array elements participating in beam forming is dynamically adjusted, a final beam pointing signal is generated, and stable relay tracking of the current period is completed. The method solves the problems of phase jump and signal attenuation during multi-array-plane switching, and is suitable for continuous tracking in a high-speed moving scene of the unmanned aerial vehicle.

The invention discloses a flexible conformal array structure scattering characteristic analysis method and device, and the method comprises the steps: carrying out the fitting of a whole flexible array surface arc length through employing a plurality of osculating circles through the evaluation of a flexible array surface structure, and determining the number of osculating circles divided by a whole arc length curve through iteration; constructing feature units to realize reconstruction of the whole flexible array plane, and calculating an initial excitation coefficient, a feature weight coefficient and a mutual coupling coefficient between the units of each flexible unit; and constructing and solving a balance equation to obtain an actual excitation coefficient of each flexible unit considering the mutual coupling effect, and calculating a total scattering field of the flexible array structure to obtain a radar cross section of the flexible array. According to the method, the scattering characteristic analysis of the flexible conformal array structure is realized, the problem of inconsistent deformation degree of each unit caused by the flexible structure is considered, a small number of characteristic units are used for replacing the units in the actual flexible array structure through an iteration mode, and the analysis efficiency is improved.

The invention discloses a two-dimensional adjustable radar cross section enhanced surface. The enhanced surface is formed by adding a one-dimensional Van atta array of a phase shifter into a feeder line and copying the one-dimensional Van atta array on the other dimension. The one-dimensional Van atta array has a low profile, and under the condition that the incoming wave direction is known, electromagnetic waves are made to backtrack along the incoming wave direction by regulating and controlling the phase of a phase shifter in the array. The unit structure of the one-dimensional Van atta array is composed of an antenna and a phase shifter. The antenna is a slot-coupled feed microstrip antenna, the radiation patch is rectangular, the dielectric substrate is arranged below the radiation patch, the antenna grounding plane with a slot is arranged below the dielectric substrate, the slot is I-shaped, the second dielectric substrate is arranged, and the T-shaped antenna feed microstrip line is arranged below the second dielectric substrate. The antenna feed microstrip line is connected with the phase shifter, and the units of the array at equal intervals are connected in pairs through microstrip lines with the same length to form a one-dimensional Van atta array.

The invention discloses an icing monitoring method and system for a corner reflector deployed based on an unmanned aerial vehicle, and relates to the technical field of environment monitoring, and the method comprises the steps: deploying a corner reflector network, collecting radar cross-section characteristics and environment parameters to generate a data packet, and carrying out the icing monitoring based on the generated data packet; calculating a signal-to-clutter ratio, obtaining a standard deviation of target positioning and phase estimation by using a Cramer-Rao lower bound method, generating a dynamic weight by using the standard deviation, obtaining a corner reflector icing thickness estimation value through data fusion, and generating an optimized signal-to-clutter ratio based on the icing thickness estimation value; and carrying out cooperative judgment by utilizing the generated optimized signal-to-clutter ratio and combining the icing thickness and the attitude deviation, triggering combined adjustment based on a judgment result, and after the combined adjustment is triggered, obtaining the SAR image again and carrying out main and auxiliary image registration and interference pair optimization. According to the invention, the sensing precision and the monitoring robustness of the unmanned aerial vehicle on the state of the corner reflector in an icing environment are improved.

The invention provides a high-gain low-RCS (radar cross section) metasurface antenna with a wave beam deflection function, which belongs to the technical field of electromagnetic metamaterials and comprises an upper-layer metasurface and a lower-layer metasurface, and multifunctional regulation and control on an electromagnetic wave radiation scattering mode are realized by adopting the upper-layer metasurface and the lower-layer metasurface which are different in size. Wherein the upper-layer metasurface is a PCM-FSS scattering-transmitting integrated metasurface, and the lower-layer metasurface is a phase gradient metasurface. When the high-gain low-RCS metasurface antenna works in a radiation mode, the upper-layer metasurface emits spherical electromagnetic waves downwards, and when the spherical waves reach the lower-layer metasurface, the spherical waves are reflected into high-gain directional wave beams with the deflection angle being 34 degrees through phase compensation and penetrate through the upper surface to be radiated to a free space; when working in a scattering mode, the upper and lower layers of metasurfaces can deflect reflected waves of external electromagnetic waves to a non-threat angular domain direction. In the frequency band of 8-18 GHz, the RCS reduction amplitude reaches 10 dB or above, and in-band and out-of-band large-amplitude RCS reduction is achieved while high-gain radiation is kept.

The invention discloses a multilayer wave-absorbing material design method, system, medium and equipment, and the method comprises the steps: building a multilayer wave-absorbing material model through electromagnetic simulation software, taking a radar cross-sectional area RCS as an optimization target, and controlling FEKO to be within a specified target frequency band; sampling electromagnetic parameters in a value range by adopting a Latin hypercube sampling algorithm, performing parameterized simulation on the multilayer wave-absorbing material model, extracting radar cross-sectional area (RCS) values to form a parameter-RCS data set, generating an electromagnetic parameter-RCS data set, training a convolutional neural network, and obtaining a multi-layer wave-absorbing material model; establishing a nonlinear mapping model from the electromagnetic parameters to a radar cross-sectional area (RCS); embedding a proxy model obtained by training into a Bayesian optimization framework, applying an expected improved function to guide a search space, automatically optimizing an electromagnetic parameter combination, and performing FEKO full-wave simulation verification; if the RCS value of the optimization result is lower than the preset threshold value, iteration continues until the performance requirement is met, and the optimal electromagnetic parameter combination is output.

The invention relates to the field of radar detection, in particular to an unmanned aerial vehicle radar cross-sectional area full-angle measurement method, which comprises the following steps of: measuring the radar cross-sectional area of a to-be-measured unmanned aerial vehicle by using an unmanned aerial vehicle with radar equipment as a measuring device; the measuring device and the to-be-measured unmanned aerial vehicle are lifted to a preset height, and the measuring device points the antenna beam direction of the radar equipment to the to-be-measured unmanned aerial vehicle; recording radar output signal power under each group of attitude angles when the to-be-measured unmanned aerial vehicle flies to a specified position with a radar distance R from the measuring device; acquiring position information and attitude angle information of the measuring device and the to-be-measured unmanned aerial vehicle; and aligning the output signal power measured by the radar with the attitude angle of the to-be-measured unmanned aerial vehicle in time, and calculating the radar scattering cross-sectional area at each attitude angle to realize the full-angle measurement of the radar scattering cross-sectional area of the unmanned aerial vehicle. According to the method, the radar cross-sectional area of the unmanned aerial vehicle can be measured at a low altitude, interference of ground clutters on the radar is avoided, and the method is not limited by a measurement space.

The invention discloses a large-scale cluster target electromagnetic scattering analysis method and system based on a parallel equivalence principle, and the method specifically comprises the steps: carrying out the geometric modeling and equivalent surface construction of each target unit in a cluster target, and generating discrete surface element information; starting a parallel computing process, and distributing a target-equivalent face by adopting a greedy algorithm; a calculation process group corresponding to each sub-domain is partitioned according to a two-dimensional Cartesian coordinate grid, a transfer operator matrix between the sub-domains is partitioned according to the same two-dimensional calculation process grid, global parallel iterative solution circulation is carried out, and the equivalent surface flow of the sub-domain is updated; and the converged equivalent surface flow of each sub-domain is used as an equivalent source, and the radar cross section RCS of the whole cluster target in the specified observation direction is synthesized through far-field radiation integration. The method has good parallel expandability and calculation efficiency, is suitable for complex and diverse cluster target scenes, reduces memory requirements and calculation time overhead, improves calculation efficiency, and is high in engineering practicability.

The invention provides a radar waveform optimization method, system and device, a medium and a program product, and the method comprises the steps: transmitting a basic radar signal employing a basic waveform, and receiving an original echo signal formed by the reflection of a target; extracting a radar cross-sectional area of a target from the original echo signal to obtain a target RCS; traversing an RCS allowable range corresponding to each target type in the feature database, and determining a matching result; determining waveform control parameters of the radar waveform; an optimized radar signal employing the optimized waveform is generated and transmitted. According to the scheme, traversal matching is carried out on the target radar cross-sectional area measured in real time and the RCS allowable range in the feature database, adaptive optimization of the radar transmitted waveform on the current target RCS is realized, in addition, the candidate PRF is systematically traversed in the PRF feasible range corresponding to the target type, and the target type is more accurate. The adaptive matching of the PRF parameter with the current target RCS and the propagation condition is realized.

The invention discloses a NiZnCu ferrite composite metasurface with a P wave band broadband and a low RCS (Radar Cross Section) based on 1-bit coding. Firstly, the impedance matching condition of the ferrite is improved through Mn < 2 + > ion doping, so that when the thickness of the NiZnCu ferrite is 2 mm, effective wave absorption with the reflection loss smaller than-10 dB is achieved within the range of 0.25 GHz to 1.0 GHz. Furthermore, NiZnCu ferrite is combined with a sandwich structure (square metal sheet / FR4 / metal back plate, 6 mm) to construct a 1-bit coding metasurface structure unit, optimal array arrangement is obtained by adopting a genetic algorithm, and directional reflection is reduced to the greatest extent. And finally, full-wave simulation software is used for verification, and the result shows that the NiZnCu ferrite composite coding metasurface can further reduce the RCS by using the diffuse reflection effect on the basis of keeping the ferrite wave absorbing effect, the range of the RCS is 0.50 GHz-0. 75 GHz, and the maximum RCS reduction value can reach 29.4 dB.

The invention relates to the technical field of radar target characteristic analysis, in particular to a radar near-field target polarization characteristic analysis method based on a vector Green function. Firstly, a target three-dimensional scattering point model is constructed, a coordinate-based scattering coefficient is defined, a full-polarization observation mode is designed, a near-field measurement matrix is calculated based on a vector Green function, and an observation model is constructed. Secondly, designing a fusion far-field constraint orthogonal matching pursuit (OMP) algorithm, realizing high-precision inversion of scattering coefficients, calculating a target far-field single-station RCS (HH / HV / VV mode) through dynamic polarization-based projection and phase compensation, and establishing a near-far field scattering characteristic mapping model; according to the method, near-field three-dimensional imaging and far-field polarization characteristic analysis are fused, the problem of insufficient cross polarization component recovery in a traditional method is solved, and the method has the advantages of high-resolution imaging, multi-physical field collaborative optimization, adaptive noise suppression and the like, and can be applied to the fields of stealth target recognition, radar cross section testing, unmanned aerial vehicle navigation and the like.

A human body pose estimation method based on radio frequency heatmap data enhancement is provided, including the following steps: firstly, obtaining the mesh data of human body pose, simulating a radar by using a physical optics method, and obtaining human body mesh features including a radar cross section by irradiating a human body mesh model; secondly, processing the human body mesh features including radar cross section to obtain preliminary simulated radar heatmaps; then inputting the preliminary simulated radar heatmaps into a heatmap conversion network map2map based on U-net, outputting synthetic radar heatmaps, and performing training; finally, combining the synthetic radar heatmaps with real radar heatmaps to construct a mixed data set, obtaining a human body pose skeleton through a human body pose estimation network based on the radar heatmaps, and performing training to complete the human body pose estimation.

Procedures, methods, architectures, apparatuses, systems, devices, and computer program products are provided for object detection over a wireless network. A method performed by a wireless transmit / receive unit (WTRU) includes receiving, from a wireless network, a configuration that includes a configured target profile for a target and information indicative of an identification of the target, wherein the configured target profile comprises a radar cross section profile associated with the target; receiving at least one signal from the wireless network; generating a measured profile based on the at least one signal; determining that the at least one signal was reflected by the target based at least in part on the information indicative of the identification of the target and a comparison between the configured target profile and the measured profile; and performing sensing measurements associated with the target using the at least one signal based at least in part on the determination.

The invention provides a broadband absorption and transmission integrated frequency selective surface with a high selection characteristic, which comprises a first loss layer, a second loss layer and a frequency selection layer, and is characterized in that the first loss layer and the second loss layer realize a transmission band with the high selection characteristic and the broadband characteristic at the same time by using dual-order resonance; the second loss layer and the frequency selection layer are cascaded to realize the absorption and transmission integrated characteristic, and the first loss layer is used for improving the low-frequency and high-frequency wave absorption characteristics and expanding the wave absorption bandwidth. Under the combined action of the first loss layer, the second loss layer and the frequency selection layer, wave transmission within the frequency band of 7.72-11.89 GHz and wave absorption within the frequency band of 1.96-7.12 GHz and the frequency band of 12.95-17.33 GHz are achieved. The antenna has high selection characteristics and broadband characteristics, can effectively suppress interference of external electromagnetic waves of other frequency bands or electromagnetic waves of a frequency band close to a communication frequency band on communication, can reduce the radar cross section of a target, and facilitates target stealth.

The invention provides an RCS (radar cross section) solving method of a uniaxial anisotropic medium based on a moment method. The method comprises the following steps of: modeling a uniaxial anisotropic scatterer or a target model to be simulated in COMSOL; the surface of the scatterer is subjected to triangular mesh generation, and the size of a mesh is determined according to the wavelengths of electromagnetic waves inside and outside the scatterer; after the parameters of the scatterer and the background medium thereof are set, the grid is imported into the moment method for solving, and compared with a finite element method for solving the problem, the background medium of electromagnetic wave radiation and the interior of the scatterer do not need to be subjected to grid subdivision, and the degree of freedom only exists on the surface of the scatterer; the degree of freedom and memory used for solving the integral equation are far smaller than those used by a finite element method, and the method shows excellent calculation efficiency and calculation precision in actual examples.

A system to be carried by a vehicle may include a dual-function antenna structure that includes a substrate and an array of antenna elements carried thereby. A beam forming network may be coupled to the dual-function antenna structure. A radar detector to be carried by the vehicle may be configured to detect radar signals directed to the vehicle. A controller may be configured to control the dual-function antenna structure to switch between a steerable phased array communication mode and a low radar cross section (RCS) mode responsive to the radar detector.

The invention relates to a radar cross section data-based electromagnetic parameter inversion method with robustness. The method comprises the steps of obtaining radar cross section data, namely RCS data of a three-dimensional airplane model, and performing preprocessing to obtain a preprocessed data set; constructing an inversion model based on a Transform and CNN (Convolutional Neural Network) hybrid architecture; constructing a forward modeling model based on depth Gaussian process regression; independently training the inversion model and the forward model, and then carrying out joint training; and evaluating the inversion prediction model subjected to joint training optimization according to the evaluation index. According to the method, the problems of morbidity, multiplicity and high-dimensional complexity in electromagnetic parameter inversion are effectively solved, and the prediction precision is improved; the multi-solution problem in the electromagnetic inversion problem is effectively solved, and the overall prediction precision is improved; and a sparse variation strategy is used, so that the calculation cost is effectively reduced, the calculation complexity of the model is reduced, the loss can be smoothly adjusted, and the stability of joint training is improved.

The invention belongs to the technical field of radar stealth testing, and particularly relates to a method for obtaining background scattering by measuring the RCS of a cone and a related device. The method comprises the following steps: mounting an eccentric cone on a low-scattering bracket, and enabling the mounting center of the eccentric cone to coincide with the rotating center of a rotary table of the low-scattering bracket; transmitting radar waves to the eccentric cone, rotating the turntable by a set angle at a fixed step length, and collecting echo signals of the eccentric cone rotating by the set angle; and performing fitting based on the acquired echo signal to obtain a background signal. According to the method, an eccentric cone is used as a calibration carrier, a high-signal-to-noise-ratio circular track is formed on a complex plane when the eccentric cone rotates, an optimal circle model is fitted by adopting an RANSAC method, and abnormal value elimination and background estimation are synchronously realized.

The invention discloses a radar low-altitude target recognition method based on a multi-dimensional feature nonlinear coupling network, and relates to the technical field of radar target intelligent recognition. The method comprises the following steps: inputting a distance-Doppler (RD) image into a trained nonlinear coupling network, and obtaining a prediction probability of at least one candidate category corresponding to a target; according to a candidate category obtained through a radar cross section (RCS) value of a target, the prediction probability of the candidate category is adjusted, the target category of the target is determined to be the candidate category with the maximum prediction probability, and the nonlinear coupling network comprises a feature extraction enhancement module, a feature decoupling fusion module, a feature modeling module and a prediction module. Therefore, the identification precision, the anti-interference capability and the robustness of the radar low-altitude target can be improved.

The invention provides a wave-transparent band frequency-adjustable frequency selection surface, which comprises a loss layer, a frequency selection layer and a bias network, the loss layer and the frequency selection layer are periodically arranged, the loss layer comprises a first resonant structure and a second resonant structure, and the frequency selection layer comprises a third resonant structure. The upper bias network and the lower bias network are respectively connected with direct-current voltages with different polarities, so that the variable capacitance diodes in the first resonant structure and the third resonant structure work under different voltages to generate different capacitance values, the resonant frequency point of the loss layer and the resonant frequency point of the frequency selection layer in the structures generate frequency shift at the same time, and finally continuous adjustability in the wave-transparent frequency band of 5.51 GHz to 6.31 GHz is achieved. Under the action of the second resonant structure and other lumped resistors of the loss layer, wave absorption within the frequency band range of 4.31 GHz to 5.15 GHz and the frequency band range of 6.31 GHz to 13.81 GHz is achieved. The device has the characteristics of continuous frequency modulation and out-of-band wave absorption, can effectively suppress interference of outside electromagnetic waves in other frequency bands or electromagnetic waves in a frequency band close to a communication frequency band on communication, can reduce the radar cross section of a target, and is beneficial to target stealth.

The invention discloses a multispectral compatible camouflage and radiant heat management device and a multispectral camouflage system based on the same, relates to the field of multispectral camouflage materials and heat management, and aims to solve the problems of poor spectrum compatibility, narrow bandwidth, insufficient heat management and high angle sensitivity in the prior art. A phase change material layer is arranged on the metal substrate layer, and a phase regulation and control layer of a chessboard structure is arranged on the phase change material layer. According to the invention, the radar scattering cross section is large, the specular reflectance is very low, the performance can still be maintained in the incidence angle range of 0-30 degrees, the reflectance is not sensitive to the incidence angle and the polarization state, laser stealth, radar stealth and infrared camouflage can be realized, the spectrum compatibility is good, the bandwidth is wide, dynamic heat dissipation in a non-window can be realized, and the performance is stable. And the heat management effect is achieved.

The invention discloses a circularly polarized antenna with an RCS (radar cross section) suppression characteristic in the field of antennas. The circularly polarized antenna comprises a first dielectric substrate and a second dielectric substrate which are stacked, a metasurface structure array is arranged on the first dielectric substrate; the metasurface structure array comprises a plurality of distributed metasurface units; the plurality of first metal patches are arranged to form a convex metasurface module, and the plurality of second metal patches are arranged to form a concave metasurface module; the convex metasurface module is embedded into the concave metasurface module to form a metasurface unit; a metal floor is arranged between the first dielectric substrate and the second dielectric substrate; the metal floor is provided with a coupling slot; one side, far away from the first dielectric substrate, of the second dielectric substrate is provided with a sequential rotation feed network; energy is input by the sequential rotation feed network, and the metasurface structure is excited through the coupling gap to form a radiation signal; good radiation performance is still kept on the premise that the radar cross section of the antenna is reduced.

The invention discloses a point cloud clustering method and device, equipment and a storage medium. The method comprises the steps that at least one space point is mapped to a preset grid system according to point cloud information detected by a vehicle under the ith frame, a space coordinate grid matrix, a Doppler velocity grid matrix and a radar cross section grid matrix are established, the point cloud information comprises point information of the at least one space point, and the point cloud information comprises point information of the at least one space point; the point information comprises coordinate information, Doppler velocity and a radar cross section; the space coordinate grid matrix, the Doppler velocity grid matrix and the radar cross section grid matrix are processed, the cluster identification number of each space point is determined, at least one space point is clustered into at least one point cloud cluster, and the cluster identification numbers of the space points in different point cloud clusters are different. According to the embodiment of the invention, different targets close to each other in a physical space can be effectively distinguished, and the accuracy of point cloud clustering is improved.

The invention provides an RCS (radar cross section) test calibration method under a far field condition, and belongs to the technical field of radar cross section test. According to the method, based on the SOL calibration technology, the RC S test calibration method under the far-field condition is designed according to the characteristics of an RCS test system under the far-field condition, system errors can be accurately separated by using the SOL calibration technology, and in the far-field RCS test, internal errors of test equipment and additional errors caused by mismatching of the equipment can be remarkably reduced; in addition, environmental errors generated in air transmission can be compensated on the basis that a high-power power amplifier is not used, and the dynamic range and sensitivity of measurement are improved. And meanwhile, a background noise vector cancellation and time domain gating method is combined, so that useful signals of the to-be-detected target can be well extracted from a plurality of interference signals, and accurate evaluation on the RCS of the to-be-detected target is completed.

The invention discloses a stealth coating material for aviation aircrafts. According to the invention, a three-layer composite structure design is adopted; the intelligent sensing layer is composed of graphene quantum dots and a piezoelectric nanofiber composite network, so that real-time sensing of electromagnetic wave signals is realized; the tunable metamaterial layer comprises a liquid crystal elastomer matrix and nickel-titanium alloy nanowires dispersed in the liquid crystal elastomer matrix, and electromagnetic parameters of the material are dynamically adjusted by applying an electric field or a temperature field; vanadium dioxide nanoparticles, a photonic crystal structure and carbon nanotube aerogel are integrated in the multispectral stealth layer, and radar, infrared and visible light multispectral synergistic stealth is achieved. The coating is further integrated with a microencapsulation repairing agent and an intelligent control system, and has the self-repairing and self-adaptive adjusting functions. Compared with the prior art, 0.1-40 GHz ultra-wide frequency band radar wave absorption is achieved, the radar cross section is reduced by 25-30 dB, the infrared radiation characteristic is reduced by 80% or above, the surface density is only 1.2-1.5 kg / m, the weight is reduced by 65% compared with a traditional coating, and a key material technical support is provided for a new generation of stealth aircrafts.