Electromagnetic Scattering

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Electromagnetic Scattering Using GPU-Based Finite Difference Frequency Domain Method

Electromagnetic Scattering Using GPU-Based Finite Difference Frequency Domain Method

The high performance of GPU has been reported in many applications such as sparse linear system solvers, physical simulations, signal processing, and image processing. These achievements have demonstrated the potential power of GPU in the field of scientific computations. The applications of GPU in the area of computational electromagnetics started in the finite-difference time-domain method (FDTD) where the acceleration ratio reached approximately 25 times compared with the CPU performance [5–7]. The graphics processing unit has also been used to speed up the method of moments (MoM) calculations for electromagnetic scattering from arbitrary three-dimensional conducting objects where 30 times acceleration ratio is achieved [8]. Further, the GPU has been used to move all electromagnetic computing code to graphical hardware using the Graphical Electromagnetic Computing (GRECO) method where it has achieved approximately 30 times faster results [9].
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Electromagnetic Scattering of Two or More Incident Plane Waves by a Perfect Electromagnetic Conductor Cylinder Coated with a Metamaterial

Electromagnetic Scattering of Two or More Incident Plane Waves by a Perfect Electromagnetic Conductor Cylinder Coated with a Metamaterial

13. Ahmed, S. and Q. A. Naqvi, “Electromagnetic scattering form parallel perfect electromagnetic conductor cylinders of circular cross-sections using iterative procedure,” Journal of Electromagnetic Waves and Applications, Vol. 22, 987–1003, 2008. 14. Fiaz, M. A., A. Ghaffar, and Q. A. Naqvi, “High frequency expressions for the field in the caustic region of a PEMC cylindrical reflector using Maslov’s method,” Journal of Electromagnetic Waves and Applications, Vol. 20, No. 5, 647–659, 2008.

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Electromagnetic Scattering from a Chiral-Coated Nihility Cylinder

Electromagnetic Scattering from a Chiral-Coated Nihility Cylinder

Electromagnetic scattering from chiral material has attracted many scientists and engineers in the last few decades [1–12]. A linearly polarized wave propagating in a chiral material undergoes a rotation of its polarization showing that the chiral media is an optically active media. Hence, TE and TM waves scattered by a chiral cylinder are coupled. Jaggard et al. studied behavior of electromagnetic waves in chiral media [1]. Engheta and Bassiri explained One- and two-dimensional dyadic Greens functions in chiral media [2]. Electromagnetic chirality and its applications has been discussed by Engheta and Jaggard [3]. Lakhtakia et al. discussed, Field equations, Huygens principle, integral equations, and theorems for radiation and scattering of electromagnetic waves in isotropic chiral media [4]. Kluskens and Newman presented the numerical results of computing the electromagnetic field scattered by a two-dimensional
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An analysis of electromagnetic scattering from finite-width strips

An analysis of electromagnetic scattering from finite-width strips

This article focuses on using the integral equa- tion model to survey the problem of electromag- netic scattering from finite-width strips. Firstly, the EFIE is surveyed as a mathematical model for electromagnetic scattering from arbitrary bodies and then it is simplified to be matched with the main problem. Since the obtained model has no analytical solution, hence an approximation method is presented for solution of the problem. For determining the scattered field we must know the current density on the strip, therefore the plots of surface current are given for different con- ditions.
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Electromagnetic scattering of vector mesons in the Sakai-Sugimoto model.

Electromagnetic scattering of vector mesons in the Sakai-Sugimoto model.

Electromagnetic scattering of vector mesons in the Sakai-Sugimoto model.. Carlos Alfonso Ballon Bayona ∗ ,.[r]

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Calculation of electromagnetic scattering VIA boundary variations and analytic continuation

Calculation of electromagnetic scattering VIA boundary variations and analytic continuation

The problem of calculating the electromagnetic scattering produced by obstacles is one of utmost importance in science and engineering. Much of what we \see" {be it through visible light or x-rays, radio or microwaves{ reaches us through a complicated combination of phe- nomena among which scattering is, in most cases, an essential element. In accordance with the substantial signicance of scattering, a great deal of eort has been devoted in the last century to treating a variety of instances of this challenging mathematical problem. Among the many resulting contributions we mention exact solutions for simple geometries, high and low frequency approximations (Kircho and Rayleigh solutions) and rigorous numerical methods.
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Modified Incomplete Cholesky Factorization for Solving Electromagnetic Scattering Problems

Modified Incomplete Cholesky Factorization for Solving Electromagnetic Scattering Problems

A column-oriented modified incomplete Cholesky factorization MIC (p, τ ) with two controlling parameters for solution of systems of linear equations with sparse complex symmetric coefficient matrices resulted from finite-element analysis of the electromagnetic scattering problem (1) is presented in this paper. Proper choices of the controlling parameters in Algorithm 6 can evidently reduce the total computation time and memory requirements compared with Algorithm 3. It is worthwhile to emphasize that the involved parameter p, which prescribes the maximal fill-ins in each row of preconditioners, makes Algorithm 6 evidently superior to Algorithm 3 in the number of fill-ins, and helps to reduce total computation time of Algorithm 6. As shown in the numerical experiments, RCM ordering is obviously superior to AMD ordering. Moreover, RCM ordering is significant to our modified incomplete Cholesky factorization. Numerical experiments show that further developments of more proper incomplete factorization algorithms and reordering schemes for electromagnetic scattering problems are deserved to be taken into consideration in the future. ACKNOWLEDGMENT
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Fast Algorithm of Wideband Electromagnetic Scattering of Homogeneous Dielectric Targets

Fast Algorithm of Wideband Electromagnetic Scattering of Homogeneous Dielectric Targets

Abstract—The PMCHWT-IE-FFT-BURA is applied to the wideband analysis of electromagnetic scattering property of homogeneous targets. Over the broad frequency band, the fast computation is achieved by the Maehly expansion on the basis of the Chebyshev approximation of the electric and magnetic currents. On the Chebyshev sampling points, PMCHWT-IE-FFT greatly reduces the memory requirement by sparsely storing the impedance matrix and decreases the computational time to the greatest degree by block acceleration of the matrix-vector product. Finally, numerical results show that the proposed method can make efficient analysis of wideband property of homogeneous targets without sacrificing accuracy much .
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Compressed Sensing for Fast Electromagnetic Scattering Analysis of Complex Linear Structures

Compressed Sensing for Fast Electromagnetic Scattering Analysis of Complex Linear Structures

Abstract—When method of moments (MOM) is applied to calculate electromagnetic scattering problems of the linear structures, traditional basis functions such as RWG functions are unable to satisfy the requirements of numerical discretization, so linear basis functions are constructed to discrete line structures. To avoid direct calculation of dense impedance matrix equation, compressed sensing (CS) in conjugation with appropriate transformation is introduced. Firstly, the impedance matrix equation is operated to obtain an alternative equation in transform domain. Secondly, CS is used to form an underdetermined equation to be solved, under the theoretical framework of CS, and the underdetermined equation can be solved by reconstruct algorithm but not iterative approach. Finally, numerical simulations of single wound axial mode helical antenna and four element linear antennas array are discussed to demonstrate the efficiency and accuracy of the proposed method.
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Electromagnetic Scattering from a Chiral-Coated PEMC Cylinder

Electromagnetic Scattering from a Chiral-Coated PEMC Cylinder

where M denotes the admittance of the PEMC boundary. It is obvious from Equations (1) and (2), that PMC corresponds to M = 0, while PEC corresponds to M → ±∞. The electrodynamics of substances with simultaneously negative values of ² and µ was given by Veselago [7]. Scattering of electromagnetic plane waves by a conducting cylinder coated with DNG materials is studied by Li and Shen [8]. Irci and Ert¨ urk investigated the transparency and scattering maximization with metamaterials-coated conducting cylinder by considering DPS, ENG, MNG, and DNG coating layers in their analysis [9]. Plane wave reflection from a planar interface of air and PEMC medium is studied [10]. Ahmed et al. studied the low contrast circular PEC cylinder buried in metamaterial half space [11]. Ahmed and Naqvi studied the PEMC cylinder buried in a dielectric half space [12]. Ahmed and Naqvi also investigated the PEMC Parallel cylinders using the iterative procedure [13], PEMC strip and strip grating [14], multiple incident plane waves incident on coated PEMC cylinder [15], directive EM-scattering from a coated PEMC cylinder [16]. Ahmed and Naqvi [17] have provided analytical solution for the scattering of electromagnetic waves from coated PEMC circular cylinder in free space, while its coating has negative permittivity and/or permeability. Jaggard et al. studied the electromagnetic waves in chiral media [18]. Engheta and Bassiri studied one- and two- dimensional dyadic Greens functions in chiral media [19]. Lakhtakia introduced the concept of nihility [20, 21]. Ahmed and Naqvi studied the directive EM-radiation of a line source in the presence of a coated nihility cylinder [22] and nihility cylinder coated with a chiral layer [23]. Engheta and Jaggard investigated the electromagnetic chirality and its applications [24]. Scattering from chiral cylinders was studied by many investigators [25–27] while Lakhtakia et al. studied nihility cylinder and perfect lenses [28–31]. Tretyakov et al. investigated waves and energy in chiral nihility [32] while Cheng et al. studied waves in planar waveguide containing chiral nihility metamaterial [33]. Electromagnetic scattering from parallel chiral cylinders of circular cross sections using an iterative procedure was studies by Al-Sharkawy and Elsherbeni [34]. Qiu et al. investigated chiral nihility effects on energy flow in chiral materials [36]. Chiral nihility slab backed by fractional dual interface is addressed by Naqvi [35].
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A Cell-Vertex Finite Volume Time Domain Method for Electromagnetic Scattering

A Cell-Vertex Finite Volume Time Domain Method for Electromagnetic Scattering

may be a more appropriate choice for the application of Ni’s novel cell- vertex based finite volume scheme, originally proposed for the non- linear Euler system. An early effort in literature to adapt Ni’s [1] novel cell-vertex based finite volume technique to the time-domain Maxwell’s equations was restricted to electromagnetic scattering from 2D perfectly conducting geometries with Transverse Magnetic (TM) polarization [7]. In the present work, Ni’s cell-vertex based finite volume technique is used to solve for electromagnetic scattering from 2D perfectly conducting geometries with TM and Transverse Electric (TE) polarization and then extended to three dimensional (3D) applications. Extension to 3D is not trivial since the second- order Lax-Wendroff scheme, in the present cell-vertex finite volume formulation, by default, requires a dual cell to approximate the second- order terms which is more complex in 3D. Finite volume discretizations using an O-O topology in 3D can also require special attention to be paid during boundary condition implementation when solved using a cell-vertex formulation.
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Numerical Modeling of Electromagnetic Scattering from Sea Surface Covered by Oil

Numerical Modeling of Electromagnetic Scattering from Sea Surface Covered by Oil

The aim of this work is to study the impacts of the oil spills on the electromagnetic scattering of the ocean sur- faces in bistatic and monostatic configurations. Therefore, in this paper, we will study the influence of the pollut- ants (oil spills) on the physical and geometrical properties of sea surface. In recent literature, the study of the electromagnetic scattering from contaminated sea surface (sea surface covered by oil spill) was limited in monostatic case. In this paper, we will study this effect in bistatic configuration, which is interested in presence of pollution in sea surface. Indeed, we will start the numerical analysis of the bistatic scattering coefficients of a clean sea surface. Then, we will study the electromagnetic signature from sea surface covered by oil spills in bistatic case using the numerical Forward-Backward Method (FBM). The obtained numerical simulation of bistatic scattering coefficients of clean and contaminated sea surface is studied as a function of various parame- ters (frequency, incident angle, sea state, type of pollutant…). And the obtained results are also compared with those published in the literature, including those using asymptotic methods.
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Numerical Method for Solving Electromagnetic Scattering Problem by Many Small Impedance Bodies

Numerical Method for Solving Electromagnetic Scattering Problem by Many Small Impedance Bodies

Electromagnetic scattering is the effect caused by EM waves such as light or ra- dio waves hitting an object. The waves will then be scattered and the scattered field contains useful information about the object, see [1] [2] [3]. Electromag- netic scattering happens in many situations, for example, sun light scattered by atmosphere, radio waves scattered by buildings or planes, and so on. The study of EM wave scattering is of great interest and importance since it helps advance many different fields ranging from Medical Technology to Computer Engineer- ing, Geophysics, Photonics, and Military Technology, see [2] [4]. Unfortunately, most wave equations cannot be solved analytically to get an exact solution. Therefore, numerical methods are sought to approximate the solution asymp- totically. Unlike solving scalar wave scattering problem [5] [6], solving EM wave scattering is much more complicated and computationally expensive due to the How to cite this paper: Tran, N.T.
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New Implementation of the Conjugate Gradient Based on the Impedance Operator to Analyse Electromagnetic Scattering

New Implementation of the Conjugate Gradient Based on the Impedance Operator to Analyse Electromagnetic Scattering

Abstract—An original iterative method based on the conjugate gradient algorithm is developed in this paper to study electromagnetic scattering. The Generalized Equivalent Circuit (GEC) method is used to model the problem and then deduce an electromagnetic equation based on the impedance operator. For validation purposes, the developed method has been applied to various iris structures. Results computed using the new implementation of the conjugate gradient are similar to theoretical values. The field and current distribution are identical to the ones obtained with the moment method. Moreover, the memory resources required for storage are significantly reduced.
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The Properties of the Electromagnetic Scattering from a Sinusoidal Water Wave

The Properties of the Electromagnetic Scattering from a Sinusoidal Water Wave

The study on electromagnetic scattering from rough surface has been the subject of intensive investigation over the past decades for its application in land and ocean remote sensing [1–14]. Normalized radar cross section (NRCS), frequency spectrum and polarimetric properties are generally used to describe scattering fields. Among these parameters, NRCS and frequency spectrum reflect the intensity of the scattering field and the line-of-sight velocity of the scatterers, respectively. In the area of ocean remote sensing, NRCS and Doppler behaviors of sea echoes have been widely used to retrieve wind field [5], sea wave spectrum [6–10] and sea surface current [11–14]. It is well known that the actual sea surface can be represented by a sum of sine waves based on the linear theory [15]. Thus, it is necessary to investigate the scattering field from a sinusoidal water wave in order to understand the properties of electromagnetic scattering from sea surface. Up to now, many analytic and numerical methods, such as Kirchhoff approximation (KA), small perturbation method (SPM), and method of moment (MoM), have been developed to evaluate NRCS and Doppler spectrum [1–4, 16–25] of the electromagnetic scattering from an oceanic surface. Although MoM is an exact numerical method to calculate electromagnetic scattering from rough surface, and the Doppler spectra of the scattering fields from water surfaces can be well simulated by it, the theoretical spectral model cannot be derived directly by MoM. Among analytic methods, KA has been widely used as the method for describing scattering from sea surface, and higher-order KA can be used to analyze the influence of the surface slope on the scattering fields [26] conveniently. Thus, in the present work, the scattering fields from a sinusoidal water wave are simulated using higher-order KA, and the influences of slope-dependent higher order scattering terms are also discussed.
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Electromagnetic Scattering by Multi-Wall Carbon Nanotubes

Electromagnetic Scattering by Multi-Wall Carbon Nanotubes

and the outer radii are given by 0.678 nm and 1.356 nm, respectively. The multiple resonances in the MWCNT are due to the interband transitions of the individual tubes. To see this, the scattering results due to SWCNT (15, 15) and (20, 20) are included for comparison. We restrict ourselves here to the energy band shown there for the sake of comparison). All the responses are normalized to the maximum peak calculated in the MWCNT case. The results demonstrate then the effect of the interaction between the walls through the mechanism of electromagnetic scattering and transmission, which has been included in the generalized reflection matrix R ˜ ¯ i,i+1 .
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An Inverse Electromagnetic Scattering Problem for an Ellipsoid

An Inverse Electromagnetic Scattering Problem for an Ellipsoid

Abstract—The scattering problem of time-harmonic electromagnetic plane waves by an impedance and a dielectric ellipsoid is considered. A low-frequency formulation of the direct scattering problem using the Rayleigh approximation is described. Considering far-field data, an inverse electromagnetic scattering problem is formulated and studied. A finite number of measurements of the leading-order term of the electric far-field pattern in the low-frequency approximation leads to specify the semi-axes of the ellipsoid. The orientation of the ellipsoid is obtained by using the Euler angles. Corresponding results for the sphere, spheroid, needle, and disc can be obtained considering them as geometrically degenerate forms of the ellipsoid for suitable values of its geometrical parameters.
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Shape Slope Parameter Distribution Modelling of Electromagnetic Scattering by Rain Drops

Shape Slope Parameter Distribution Modelling of Electromagnetic Scattering by Rain Drops

Recently, Brawn and Upton [13] fitted the µ -Λ relation for rain rates greater than 1 mm/hr based on their drop size data measured at Dumfries and Galloway, Scotland, using the Thies and[r]

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Electromagnetic Scattering Properties of a Resonant Plasma

Electromagnetic Scattering Properties of a Resonant Plasma

A. Choice of Experimental Method B.. When this resonance effect occurs, the effective scattering diameter of the cylinder may be many times greater than its physic[r]

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ANALYSIS OF TWO-DIMENSIONAL MULTIREGION MODEL FOR LARGE-SCALE ELECTROMAGNETIC SCATTERING

ANALYSIS OF TWO-DIMENSIONAL MULTIREGION MODEL FOR LARGE-SCALE ELECTROMAGNETIC SCATTERING

In this paper an iterative multiregion technique has been proposed to solve large-scale electromagnetic problems that can be decomposed into separate subregions using the FDFD method. This procedure starts by dividing the original computational domain into separate subregions where the solution is easily performed by the FDFD method followed by an iterative interaction process between the subregions. The new approach proposed here is found to be efficient in producing accurate results for the original problem with moderate saving in computer memory usage. The two-dimensional problem presented in this paper is a test bed for the more practical three-dimensional configurations, for which significant memory saving is expected.
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