- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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[IEEE 2018 IEEE 17th International Conference on Mathematical Methods in Electromagnetic Theory (MMET) - Kiev (2018.7.2-2018.7.5)] 2018 IEEE 17th International Conference on Mathematical Methods in Electromagnetic Theory (MMET) - Electromagnetic Scattering of THz Waves from a Microsize Graphene-Sandwiched Thin Dielectric Strip
摘要： Two-dimensional (2-D) scattering of the H-polarized plane wave by a composite flat material strip is investigated. It is made as graphene-dielectric-graphene sandwich-like structure which is placed in the free space. Our modeling uses singular integral equations and Nystrom discretization. The scattering cross-section and the absorption cross-section are computed, together with the relative error plots for the current and the far field. The surface plasmon resonances on the graphene strips and the thin dielectric layer performance are evaluated.
关键词： strip,electromagnetic scattering,resonance
更新于2025-09-23 15:23:52
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Sparsifying preconditioner for the time-harmonic Maxwell's equations
摘要： This paper presents the sparsifying preconditioner for the time-harmonic Maxwell’s equations in the integral formulation. Following the work on sparsifying preconditioner for the Lippmann–Schwinger equation, this paper generalizes that approach from the scalar wave case to the vector case. The key idea is to construct a sparse approximation to the dense system by minimizing the non-local interactions in the integral equation, which allows for applying sparse linear solvers to reduce the computational cost. When combined with the standard GMRES solver, the number of preconditioned iterations remains small and essentially independent of the frequency. This suggests that, when the sparsifying preconditioner is adopted, solving the dense integral system can be done as efficiently as solving the sparse system from PDE discretization.
关键词： Electromagnetic scattering,Preconditioner,Maxwell’s equations,Sparse linear algebra
更新于2025-09-23 15:23:52
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Fast modeling of electromagnetic scattering from 2D electrically large PEC objects using the complex line source type Green's function
摘要： This study introduces an alternative approach to the numerical solution of two-dimensional (2D) electromagnetic scattering problems by a numerical method of moments (MoM). The real source position vector is replaced by a complex quantity, then Green’s function generates a complex source point beam, therefore the interactions between the far zone elements in the impedance matrix are neglected, except the basis functions near to the edges, strongly localizing the impedance matrix. The memory storage increases with the number of edges, but for a fixed number of the edges, it is linearly proportional with N, i.e. O(N). Consequently, the overall running time can be drastically reduced and the far zone scattering pattern and the near field can be found. The proposed procedure is first explained for the single perfectly electrically conducting (PEC) strip geometry, then extended to the scattering by 2D PEC objects with closed polygonal cross-sections. Numerical results are presented for a strip and a square cylinder in both polarizations. The relative errors are also compared with the standard MoM.
关键词： computational electromagnetics,radar cross section,Electromagnetic scattering
更新于2025-09-23 15:23:52
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Characterization of ICA for Scattering From Cylindrical Components of Vegetation
摘要： The capability of reliably describing the electromagnetic scattering behavior by a dielectric finite cylinder is important in many applications, in particular, for microwave remote sensing of vegetated terrain. Previous lack of accurate analytical or semianalytical cylinder scattering model has led to the popularity of the infinite cylinder approximation (ICA) approach even at present. Yet, the performance of ICA has not been systematically quantitatively characterized in the literature. This letter fills in the gap, and demonstrates that ICA leaves much to be desired in many aspects.
关键词： Electromagnetic scattering,homogeneous cylinder,infinite cylinder approximation (ICA)
更新于2025-09-23 15:22:29
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[IEEE 2018 IEEE International Conference on Computational Electromagnetics (ICCEM) - Chengdu (2018.3.26-2018.3.28)] 2018 IEEE International Conference on Computational Electromagnetics (ICCEM) - MLFMA-ACA Based Method for Efficient Calculation of Scattering from Underground Targets
摘要： Electromagnetic (EM) non-destructive evaluation (NDE) of underground targets is of great significance for the safety of urban construction. Succesful detection of underground targets during construction depends on the accurate and efficient simulation of wave propagation. Among the most popular numerical methods in electromagnetics, surface integral equation (SIE) based method of moments (MoM) is used to simulate the scattering from underground targets in this paper. While MoM has high computational complexity O(N^2) and memory cost O(N^2) if iterative solver is applied, where N is the number of unknowns. As one of the most efficient fast algorithms, multi-level fast multi-pole algorithm (MLFMA) is used to reduce the computational complexity and memory cost. However, MLFMA is more difficult to calculate in this case because of the coupling action between rough surface and target has its limitations. So, adaptive cross approximation (ACA) is used to solve this problem. In this paper, a hybrid method combining MLFMA and ACA (MLFMA-ACA) is proposed to compute the scattering from underground targets. While MLFMA is used to compress the coupling matrix between rough surface and target, ACA is added to compress the coupling matrix between different media targets. The combination between them can build a more efficient method to compute scattering from underground targets.
关键词： method of moment,multi-level fast multi-pole algorithm,Adaptive cross approximation,electromagnetic scattering,underground target
更新于2025-09-23 15:22:29
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[IEEE IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Valencia, Spain (2018.7.22-2018.7.27)] IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Investigation of Doppler Spectra of Sea Backscatter Through Large-Scale Monte Carlo Simulations: Direct Numerical Solution And Approximate Models
摘要： The study simulates and analyses backscattering of a time-harmonic (continuous-wave) X-band signal from evolving ocean-like surfaces in the 2D space. For the same surface realization, the scattered field is evaluated using the direct numerical solution of a first-principles boundary integral equation, and with two approximate models: the coherent Two-Scale Model (CTSM) and the second-order Small Slope Approximation (SSA2). Large Monte Carlo ensembles are built up to evaluate well-averaged Doppler spectra. The investigation focuses on the two spectral parameters: centroid and width, with alternative definitions for the latter being discussed. A broad and finely sampled range of incidence angles is considered, providing a comprehensive and detailed view at the behavior of these quantities from nadir to low grazing. Using the same set of surfaces when calculating backscattered fields according to the exact and approximate methods provides a rigorous test for the accuracy of the chosen scattering models. The reported high-quality data from direct numerical simulations can serve as a benchmark for other scattering formulations.
关键词： numerical simulations,sea surface electromagnetic scattering,Doppler spectrum
更新于2025-09-23 15:21:21
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[IEEE IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Valencia, Spain (2018.7.22-2018.7.27)] IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Electromagnetic Modeling of Ships in Maritime Scenarios: Geometrical Optics Approximation
摘要： Global Navigation Satellite System-Reflectometry (GNSS-R), is succesfully employed for ocean altimetric and scatterometric applications. Recently, it has been suggested that GNSS-R can also be used for ship detection applications. To this purpose, an accurate electromagnetic modeling of the bistatic radar cross section of a ship lying over the sea surface would be very helpful. However, existing models are typically limited to monostatic configurations, thus restricting their applicability in multistatic scenarios, such as GNSS-R systems. In this work, we show a procedure to determine the bistatic radar cross section of a ship target, under the geometrical optics approximation. Numerical results show the impact of the geometry of acquisition and polarization on the bistatic radar cross section.
关键词： geometrical optics,radar cross section,Electromagnetic scattering,ship detection
更新于2025-09-23 15:21:21
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[Springer Series in Optical Sciences] Fano Resonances in Optics and Microwaves Volume 219 (Physics and Applications) || A Full-Retarded Spectral Technique for the Analysis of Fano Resonances in a Dielectric Nanosphere
摘要： We introduce a representation of the electromagnetic ?eld scattered by a homogeneous sphere in terms of a set of full-retarded modes independent of its permittivity. Within this framework, we introduce the orthogonality properties of the modes, their resonance conditions, and their classi?cation into narrow and broad modes. We also discuss the role played by the material properties in determining the resonant width of a given mode and in enabling or preventing the multimode interference. We use this theory to unveil the origin of Fano lineshapes in the scattering ef?ciency of a spherical nanoparticle, by identifying the interfering modes responsible for peaks and dips. Eventually, by using the introduced theoretical approach, we design the permittivity of a homogeneous sphere of size comparable to the incident wavelength to cancel its backscattering through directional multimode interference.
关键词： full-retarded modes,Fano resonances,electromagnetic scattering,permittivity design,dielectric nanosphere
更新于2025-09-23 15:21:21
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Spatial Retrieval of Broadband Dielectric Spectra
摘要： A broadband soil dielectric spectra retrieval approach (1 MHz–2 GHz) has been implemented for a layered half space. The inversion kernel consists of a two-port transmission line forward model in the frequency domain and a constitutive material equation based on a power law soil mixture rule (Complex Refractive Index Model—CRIM). The spatially-distributed retrieval of broadband dielectric spectra was achieved with a global optimization approach based on a Shuffled Complex Evolution (SCE) algorithm using the full set of the scattering parameters. For each layer, the broadband dielectric spectra were retrieved with the corresponding parameters thickness, porosity, water saturation and electrical conductivity of the aqueous pore solution. For the validation of the approach, a coaxial transmission line cell measured with a network analyzer was used. The possibilities and limitations of the inverse parameter estimation were numerically analyzed in four scenarios. Expected and retrieved layer thicknesses, soil properties and broadband dielectric spectra in each scenario were in reasonable agreement. Hence, the model is suitable for an estimation of in-homogeneous material parameter distributions. Moreover, the proposed frequency domain approach allows an automatic adaptation of layer number and thickness or regular grids in time and/or space.
关键词： soil measurements,electromagnetic scattering inverse problems,dielectric measurements,modeling,microwave propagation,dielectric materials
更新于2025-09-23 15:21:01
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[IEEE 2019 PhotonIcs & Electromagnetics Research Symposium - Spring (PIERS-Spring) - Rome, Italy (2019.6.17-2019.6.20)] 2019 PhotonIcs & Electromagnetics Research Symposium - Spring (PIERS-Spring) - Validation of Hertzian Electromagnetism in a Rectangular Waveguide with Rotating PEC Termination
摘要： We provide a general formulation of electromagnetic scattering by a Perfect Electrical Conductor (PEC) object in arbitrary motion in the context of Hertzian Electrodynamics, which is followed by an application to the canonical problem of scattering of dominant TE mode incidence in presence of a PEC termination in accelerated rotational motion. Analytical solutions, which apply for arbitrary variations of angular velocity, are derived and supported with measurement results.
关键词： rectangular waveguide,PEC termination,TE mode,electromagnetic scattering,Hertzian Electrodynamics
更新于2025-09-23 15:19:57