Scattering Of Electromagnetic Waves Research Articles

A Revisit of Electromagnetic Wave Scattering by a Metal Isotropic Body in a Lossless Environment with Magnetic Sensor Excitation.

This paper investigates the electromagnetic fields being scattered by a metal spherical object in a vacuum environment, providing a numerical implementation of the obtained analytical results. A time-harmonic magnetic dipole source, far enough, emits the incident field at low frequencies, oriented arbitrarily in the three-dimensional space. The aim is to find a detailed solution to the scattering problem at spherical coordinates, which is useful for data inversion. Based on the theory of low frequencies, the Maxwell-type problem is transformed into Laplace's or Poisson's interconnected equations, accompanied by the proper boundary conditions on the perfectly conducting sphere and the radiation conditions at infinity, which are solved gradually. Broadly, the static and the first three dynamic terms are sufficient, while the terms of a higher order are negligible, which is confirmed by the field graphical representation.

Electromagnetic Wave Scattering at the Junction of Semi-Infinite 2-D Media With Forced Refraction

Electromagnetic Wave Scattering at the Junction of Semi-Infinite 2-D Media With Forced Refraction

Asymptotic approach for stable computations of the spherically layered media theory with large orders and small arguments.

The computation of electromagnetic wave scatterings of a layered sphere is a canonical problem. Lorentz-Mie theory is suitable for plane wave incidence whereas spherically layered media theory can deal with arbitrary incident waves. Both theories suffer from the notorious numerical instabilities due to the involved Bessel functions with large order, small argument or high loss. Logarithmic derivative method has been proposed to solve the numerical issues with these theories. In this paper, by employing the equivalence between the asymptotic formulas of Bessel functions for small argument and for large order, the numerical issues with the spherically layered theory under both large order case and small argument case can be solved in a unified manner by canceling out the diverging terms in the asymptotic formulas. The derived stable formulas are simpler and faster than those based on logarithmic derivative method. It is shown that the derived formulas are good approximations to the canonical ones but are more numerically stable. The large lossy issue can be solved similarly.

Efficient Methods for Solving Electromagnetic Wave Scattering from Dielectric Objects Using Method of Moments with Interpolation-FFT

Efficient Methods for Solving Electromagnetic Wave Scattering from Dielectric Objects Using Method of Moments with Interpolation-FFT

Direct Electromagnetic Wave Scattering Calculation Using Methods of Moments through Layered Rough Surface

This thesis focuses on the direct calculation of electromagnetic wave scattering through layered rough surfaces using the Method of Moments. The study aims to contribute to existing knowledge by addressing the problems associated with accurately predicting scattered electromagnetic fields from rough surfaces with layered structures. By using the Method of Moments, this research seeks to provide insights into the behavior of electromagnetic waves when interacting with multi-layered rough surfaces, offering valuable implications for practical engineering applications and the development of advanced computational tools for electromagnetic wave analysis. In practical terms, the surface is typically divided into small patches, and the electromagnetic field at each patch is determined using MoM. This involves solving integral equations describing the interaction between the induced currents on the surface and the incident field. The layered structure may require additional equations to model the reflection of waves and the transmission at the boundaries between the layers. The direct problem is also examined in a two-dimensional picture, where the rough surface profile and the medium are known parameters, and the electromagnetic waves scattered from the surface to the entire space are the unknowns. The rough surface is considered to have a finite length and can be deterministic or arise from a stationary stochastic random process, with a focus on Gaussian-type rough surfaces. The roughness is considered as two basic types: as a perfect electric conductor (PEC) in free space and as a boundary between two dielectric media. The equations of integration obtained are based on the scalar solution of Green's theory, Helmholtz equations, and using Hankel type green functions as kernels due to the one-dimensional nature. The MoM is extensively used to solve these integral equations and is compared to asymptotic approaches and analytical. Various simulations are conducted to test the feasibility of the algorithms, and the results are thoroughly discussed. The study of electromagnetic wave scattering in one-dimensional rough surfaces involves the direct problem, where the field distribution in the whole space is determined using the equation of integration. These equations take into account the surface roughness and medium parameters they are solved using the Method of Moments (MoM) by expressing the field distribution on the surface using basis functions. The direct calculation of electromagnetic wave scattering through a layered rough surface using the Method of Moments (MoM) is a computationally intensive process and complex and. It contains simulating the interaction of EM waves with a complex surface, which presents challenges due to the multiple layers with different properties, and a roughly surface causing and diffraction of incident waves and scattering. When working with a layered rough surface increases the electromagnetic wave interaction complexity. Additional multiple layers introduce considerations, such as layer interfaces and accounting for different material abilities. This requires careful modeling and analysis to exactly capture the behavior of electromagnetic waves as they traverse through and interact with layers. MoM, a commonly used numerical method for solving electromagnetic scattering problems, discreteness the surface into small segments and solves integral equations to determine the fields that is scattered. This approach allows for a maximum analysis of electromagnetic interactions at a grained level.

The electromagnetic wave propagation in discontinuous waveguide containing plasma

The current study examines how electromagnetic waves scatter when encountering plasma medium and step-discontinuities. The physical model used in the study includes dielectric and plasma layers separated by horizontal plates made of metallic conducting material. The problem of interest is solved using the Mode-matching technique, which projects the solution onto an orthogonal basis to explain how planar mode excitation is reflected, transmitted, and attenuated. The mathematical and intrinsic power analyses confirm the accuracy of the algebra and solution scheme used. The analysis provides an understanding of both the mathematical and theoretical aspects of the structure under consideration.

Two-Dimensional Scattering of Line Source Electromagnetic Waves by a Layered Obstacle

We consider the scattering problem of line source electromagnetic waves using a multi-layered obstacle with a core, which may be a perfect conductor, a dielectric, or has an impedance surface. We formulate this problem in two dimensions and we prove some useful scattering relations. In particular, we state and prove a reciprocity principle and a general scattering theorem for line source waves for any possible positions of the source. These theorems can be used to approximate the far-field pattern in the low-frequency theory. Moreover, an optical theorem is recovered as a corollary of the general scattering theorem. Finally, we obtain a mixed reciprocity relation which can be used in proving the uniqueness results of the inverse scattering problems.

Numerical Investigation of Electromagnetic Wave Scattering from an Inhomogeneous Solid and a Curvilinear Perfectly Conducting Screen

Numerical Investigation of Electromagnetic Wave Scattering from an Inhomogeneous Solid and a Curvilinear Perfectly Conducting Screen

Modified Method of Physical Optics for Calculating Electromagnetic Wave Scattering on Non-Convex Objects

In order to solve the problem of electromagnetic wave scattering on non-convex objects, a combined method based on the method of physical optics with corrections for multiple reflections was discussed. The calculation of these corrections was carried out by the ray method. The article considered the effect of taking into account the curvature of the surface on the calculation error. The results of the calculations of the test example were compared with the calculations by the rigorous method of moments.

Robust carbon bridge to construct double-shell FeCo@C@Al2O3 heterogeneous structure with dual-function for extraordinary microwave absorption and anti-corrosion

The complexity of the environment leads to corrosion and failure of absorbing functions. The encapsulation and surface modification of multi-gradient structures are typical ways to address this challenge. Herein, a FeCo@C@Al2O3 core–shell heterostructure is developed for the dual functions of absorbing and anti-corrosion using the chemical vapor deposition and hydrolysis of the aluminum sulfate. This unique double-shell structure provides more multiple interface relaxation polarizations, electromagnetic wave scatterings. And the robust carbon layer produces sufficient conduction loss for the FeCo@C@Al2O3. Compared with pure FeCo, the absorption capacity of FeCo@C@Al2O3 increases up to 1.4 times, the minimum reflection loss value achieves −46.7 dB at the thickness of 1.4 mm. And the maximum effective absorption bandwidth is up to 9.3 GHz. While it possesses minimum total RCS value of −13.29 dB∙m2, reflecting the optimal absorbing stealth performance. Besides, the coating Al2O3 layer effectively isolates the diffusion of corrosion ions including Cl-, H2O and O2, the corrosion current and polarization resistance of FeCo@C@Al2O3 are well adjusted to 7.96 × 10-8 A/cm2 and 5.40 × 105 Ω·cm2, respectively. Therefore, the FeCo@C@Al2O3 heterostructure provides an updated platform for the research and development of new absorbing and anti-corrosion materials.

Investigation and Methods for Solving Problems of Scattering of Electromagnetic Waves on Three-Dimensional Anisotropic Dielectric Structures

Investigation and Methods for Solving Problems of Scattering of Electromagnetic Waves on Three-Dimensional Anisotropic Dielectric Structures

Investigation and Methods for Solving Problems of Scattering of Electromagnetic Waves on Three-Dimensional Anisotropic Dielectric Structures

The problems of scattering of electromagnetic waves by anisotropic dielectric structures are studied on the basis of volumetric singular integral equations. Existence and uniqueness theorems for solutions are given for a wide class of media, including lossless media. An efficient method for solving integral equations based on the collocation method and fast discrete Fourier transform algorithms is described.

Scattering and conversion of electromagnetic and gravitational waves by Reissner-Nordström black holes: The Regge pole description

We investigate the problem of scattering and conversion of monochromatic planar gravitational and electromagnetic waves impinging upon a Reissner-Nordstr\"om black hole using a Regge pole description, i.e., a complex angular momentum approach. For this purpose, we first compute numerically the Regge pole spectrum for various charge-to-mass ratio configurations. We then derive an asymptotic expressions for the lowest Regge poles, and by considering Bohr-Sommerfeld-type quantization conditions, obtain the spectrum of weakly damped quasinormal frequencies from the Regge trajectories. Next, we construct the scattering and conversion amplitudes as well as the total differential cross sections for different processes using both a complex angular momentum representation and a partial wave expansion method. Finally, we provide an analytical approximation of the scattering and conversion cross sections of different processes from asymptotic expressions for the lowest Regge poles and the associated residues based on the correspondence Regge poles, ``surface waves'' propagating close to the photon (graviton) sphere. This allows us to extract the physical interpretation encoded in the partial wave expansions in the high-frequency regime (i.e., in the short-wavelength regime), and to describe semiclassically with very good agreement both black hole glory and a large part of the orbiting oscillations, thus unifying these two phenomena from a purely wave point of view.

Scattering of electromagnetic waves by plasma layer sandwiched between two layers of thin glass

Scattering of electromagnetic waves by plasma layer sandwiched between two layers of thin glass

Scattering of electromagnetic waves induced by an shallow triangular cavity

AbstractIn this article, a solution for electromagnetic scattering by a shallow triangular cavity is suggested using the modal expansion technique. First, a domain decomposition approach is employed to divide the half‐space above the cavity into two sub‐regions. The tangential fields within the sub‐regions are expanded in terms of an infinite series of appropriate basis functions in two different coordinate systems. The fields are then expressed in a similar coordinate system by utilising the Graf's addition theorem. Eventually, the unknown coefficients are computed through satisfying the continuity of the tangential fields at an auxiliary boundary. Some examples are given to demonstrate the validity and reliability of the proposed method.

Investigations on electromagnetic wave scattering simulation from rough surface: Some instructions for surface roughness measurement based on machine vison

There are many experimental variables in the research of surface roughness measurement based on machine vision technology, such as light incident angle, light wavelength, workpiece material, surface features. It is, however, time-consuming and also labour-intensive to conduct experiments considering all these variables. In this work, we proposed to conduct Electromagnetic Wave Scattering Simulation considering these variables using finite element method (FEM) in order to give instructions for actual imaging design. The simulation process is more theoretically robust, more efficient and cost-effective rather than actual experiments with empirical models. In the simulation process, a simulation model is designed first. In this model, the light incident angles θ include 15°, 30°, 45°, 60° and 75°; the light wavelengths λ include 400 nm, 550 nm and 700 nm corresponding to blue, green and red; the workpiece materials include stainless steel (SUS), copper (Cu), aluminium (Al), and silicon carbide (SiC). Then, a series of rough surface with different surface roughness values are obtained by defining cosine functions and non-Gaussian surfaces. The simulation results show that given material, when 0≤Ra ≤ 0.1 μm, the performance of small θ is obviously better than that of large θ. When 0.1≤Ra ≤ 1 μm, large θ is better (θ ≥ 60°). This derives to obtain better measurement accuracy.

An Efficient and Error-Controllable Angular Sweep Algorithm for Electromagnetic Wave Scattering and its Analysis

The angular sweep of electromagnetic wave scattering is formulated as a matrix equation with multiple right-hand sides (RHSs). Although the low-rank approximation of an RHS matrix is a popular choice for reducing the computational costs of multiple RHSs, only a small amount of research has been conducted to explore how this approximation impacts the solution quality. Furthermore, there has not been sufficient research on the quality of the solution as a function of the accuracy of the iterative solver. We present an error analysis of the approximated solution considering both the reduced number of RHSs and the tolerance of the iterative solver. Based on the error analysis, a new angular sweep algorithm is proposed with fine-tuned tolerances of the iterative solver for individual singular vectors. The different tolerances for each singular vector increase the efficiency of the proposed algorithm. Another benefit of the proposed algorithm is that the error can be bounded by a user-defined global tolerance. In addition, a variant of the generalized conjugate residual method for multiple RHSs is introduced to accelerate iterative solvers. Finally, numerical validation is conducted with three examples in which the discontinuous Galerkin surface integral equation method is applied. The experiments support two conclusions: tight upper and lower bounds of the solution error exist, and fine-tuning the tolerances reduces the computational costs.

Resonant Scattering of GHz Electromagnetic Waves by a Linear Structure of Two Dielectric Rings on a Magnetic Dipole Mode

Resonant Scattering of GHz Electromagnetic Waves by a Linear Structure of Two Dielectric Rings on a Magnetic Dipole Mode

Radiation pressure by electron cyclotron waves on density fluctuations

The presence of turbulence in the form of large density fluctuations and coherent filamentary structures in the edge region of fusion plasmas has been well documented. Radio frequency waves, launched from structures near the wall of a tokamak, have to propagate through this turbulent plasma before reaching the core. These density fluctuations can reflect, refract, and diffract the electromagnetic waves, thereby modifying the flow of energy and momentum to the core plasma. Conversely, the radiation pressure of the radio frequency waves can modify the turbulence, whether it is in the edge region or in the core. This article examines some consequences of the radiation force induced by electron cyclotron waves in plasmas. The effect of waves on two different representations of density fluctuations are studied. In the first representation, suitable for both edge and core plasmas, it is assumed that a planar interface separates two different density regimes. The physics basis for the radiation force on an interface separating two different scalar dielectric media was first elucidated by Poynting in 1905 [J. H. Poynting, The London, Edinburgh, and Dublin Philosophical Magazine and Journal of Science9, 393-406 (1905)]. Poynting’s results are explained within the context of Snell’s law and Fresnel equations, and, subsequently, extended to magnetized plasmas. The analysis shows that electron cyclotron waves lead to peaking of the density profile – the interface is pushed towards the region of higher density. The planar interface approximation is the basis of Kirchhoff theory [P. Beckmann and A. Spizzichino,The Scattering of Electromagnetic Waves from Rough Surfaces(Artech, Massachusetts, 1987) Chapter 3] used to study wave scattering by turbulent media. In the second representation, appropriate for coherent structures in edge plasmas, the radiation force on a cylindrical filament embedded in a background plasma is determined using the Maxwell stress tensor. A detailed study reveals that the radiation force has a different effect on filaments – those with densities higher than the background density are pulled in towards the source launching the waves, while the lower density filaments are pushed away. The reaction on a filament is large enough to be observed experimentally.

Scattering of Electromagnetic Waves by a Multi-element System of Pass-through Resonators in a Rectangular Waveguide

Scattering of Electromagnetic Waves by a Multi-element System of Pass-through Resonators in a Rectangular Waveguide