scholarly journals A Generalized case of Electromagnetic Scattering from a finite number of Ferromagnetic cylinders

2015 ◽  
Vol 4 (3) ◽  
pp. 8 ◽  
Author(s):  
T. Kumar ◽  
N. Kalyanasundaram ◽  
B. K. Lande
Keyword(s):  
Finite Number ◽  
Electromagnetic Scattering ◽  
Scattered Field ◽  
Near Field ◽  
Scattering Problem ◽  
Normal Incidence ◽  
Generalized Solution ◽  
Numerical Results ◽  
Infinite Length ◽  
Angle Of Incidence

A generalized solution of the scattering problem from an array containing a finite number of axially magnetized ferromagnetic cylinders of infinite length placed in free space is presented in this paper. The analysis is carried out by matching the tangential boundary conditions at the surface of each cylinder to find the unknown expansion coefficients of the scattered field. Planar arrays consist of a finite number of ferromagnetic microwires are considered to obtain the numerical results for TMz and TEz polarizations in terms of the variation in scattered field components of the near field and scattering cross section (SCS) with respect to angle of incidence, radius of microwires, spacing among the microwires and operating frequency. For validation purpose, numerical results of the proposed analysis specialized for the case of single microwire and normal incidence for TMz polarization are compared with the results available in the literature for the specialized case and both are found to be matched completely.

scholarly journals Through-the-Wall Microwave Imaging: Forward and Inverse Scattering Modeling

Sensors ◽  
2020 ◽  
Vol 20 (10) ◽  
pp. 2865 ◽  
Author(s):  
Alessandro Fedeli ◽  
Matteo Pastorino ◽  
Cristina Ponti ◽  
Andrea Randazzo ◽  
Giuseppe Schettini
Keyword(s):  
Electromagnetic Field ◽  
Inverse Scattering ◽  
Scattered Field ◽  
Scattering Problem ◽  
Inverse Scattering Problem ◽  
Microwave Imaging ◽  
Numerical Results ◽  
Lebesgue Spaces ◽  
Non Linear ◽  
Inversion Procedure

The imaging of dielectric targets hidden behind a wall is addressed in this paper. An analytical solver for a fast and accurate computation of the forward scattered field by the targets is proposed, which takes into account all the interactions of the electromagnetic field with the interfaces of the wall. Furthermore, an inversion procedure able to address the full underlying non-linear inverse scattering problem is introduced. This technique exploits a regularizing scheme in Lebesgue spaces in order to reconstruct an image of the hidden targets. Preliminary numerical results are provided in order to initially assess the capabilities of the developed solvers.

Electromagnetic scattering by a dielectric sphere partially buriedin an infinte plane

2002 ◽  
Vol 80 (9) ◽  
pp. 979-986
Author(s):  
A -K Hamid ◽  
M Hamid
Keyword(s):  
Plane Wave ◽  
Electromagnetic Scattering ◽  
Plane Electromagnetic Wave ◽  
Ground Plane ◽  
Scattering Problem ◽  
Dielectric Constants ◽  
Angle Of Incidence ◽  
Spherical Scatterer ◽  
Incident Plane ◽  
The Given

An analytical solution of the scattering problem of a plane electromagnetic wave scattered by a dielectric spherical scatterer residing or partially buried in an infinite perfectly conducting ground plane is formulated in conjunction with the method of images. With imaging, the geometry is replaced by two touching or overlapping dielectric spheres in the absence of the ground plane, but with the given incident plane wave and its plane-wave image to satisfy the boundary conditions on the ground plane in the original problem. Numerical results are presented for the normalized scattering cross section at an arbitrary height from the ground plane, at any specific angle of incidence, and different relative dielectric constants. PACS Nos.: 41.10H, 41.90

scholarly journals A Numerical Method for Analyzing Electromagnetic Scattering Properties of a Moving Conducting Object

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
Lei Kuang ◽  
Shouzheng Zhu ◽  
Jianjun Gao ◽  
Zhengqi Zheng ◽  
Danan Dong
Keyword(s):  
Electromagnetic Scattering ◽  
Scattered Field ◽  
Moving Boundary ◽  
Numerical Approach ◽  
Numerical Results ◽  
Conducting Surface ◽  
Time Harmonic ◽  
Object Based ◽  
Improved Technique ◽  
Difference Time

A novel numerical approach is developed to analyze electromagnetic scattering properties of a moving conducting object based on the finite-difference time-domain (FDTD) algorithm. Relativistic boundary conditions are implemented into the FDTD algorithm to calculate the electromagnetic field on the moving boundary. An improved technique is proposed to solve the scattered field in order to improve the computational efficiency and stability of solutions. The time-harmonic scattered field from a one-dimensional moving conducting surface is first simulated by the proposed approach. Numerical results show that the amplitude and frequency of the scattered field suffer a modulation shift. Then the transient scattered field is calculated, and broadband electromagnetic scattering properties of the moving conducting surface are obtained by the fast Fourier transform (FFT). Finally, the scattered field from a two-dimensional moving square cylinder is analyzed. The numerical results demonstrate the Doppler effect of a moving conducting object. The simulated results agree well with analytical results.

scholarly journals Analysis of Scattering by Plasmonic Gratings of Circular Nanorods Using Lattice Sums Technique

Sensors ◽  
2019 ◽  
Vol 19 (18) ◽  
pp. 3923
Author(s):  
Jandieri ◽  
Yasumoto ◽  
Pistora ◽  
Erni
Keyword(s):  
Refractive Index ◽  
Photonic Crystals ◽  
Electromagnetic Scattering ◽  
Near Field ◽  
Planar Geometry ◽  
Refractive Index Sensor ◽  
Infinite Length ◽  
Absorption Bands ◽  
Lattice Sums ◽  
Plasmonic Gratings

A self-contained formulation for analyzing electromagnetic scattering by a significant class of planar gratings composed of plasmonic nanorods, which were infinite length along their axes, is presented. The procedure for the lattice sums technique was implemented in a cylindrical harmonic expansion method based on the generalized reflection matrix approach for full-wave scattering analysis of plasmonic gratings. The method provided a high computational efficiency and can be considered as one of the best-suited numerical tools for the optimization of plasmonic sensors and plasmonic guiding devices both having a planar geometry. Although the proposed formalism can be applied to analyze a wide class of plasmonic gratings, three configurations were studied in the manuscript. Firstly, a multilayered grating of silver nanocylinders formed analogously to photonic crystals was considered. In the region far from the resonances of a single plasmonic nanocylinder, the structure showed similar properties compared to conventional photonic crystals. When one or a few nanorods were periodically removed from the original crystal, thus forming a crystal with defects, a new band was formed in the spectral responses because of the resonant tunneling through the defect layers. The rigorous formulation of plasmonic gratings with defects was proposed for the first time. Finally, a plasmonic planar grating of metal-coated dielectric nanorods coupled to the dielectric slab was investigated from the viewpoint of design of a refractive index sensor. Dual-absorption bands attributable to the excitation of the localized surface plasmons were studied, and the near field distributions were given in both absorption bands associated with the resonances on the upper and inner surfaces of a single metal-coated nanocylinder. Resonance in the second absorption band was sensitive to the refractive index of the background medium and could be useful for the design of refractive index sensors. Also analyzed was a phase-matching condition between the evanescent space-harmonics of the plasmonic grating and the guided modes inside the slab, leading to a strong coupling.

scholarly journals Efficient Near-Field Analysis of the Electromagnetic Scattering Based on the Dirichlet-to-Neumann Map

2019 ◽  
Vol 9 (19) ◽  
pp. 4179
Author(s):  
Perrotta ◽  
Maffucci ◽  
Ventre ◽  
Tamburrino
Keyword(s):  
Boundary Conditions ◽  
Electromagnetic Scattering ◽  
Near Field ◽  
Scattering Problem ◽  
Computational Cost ◽  
Field Analysis ◽  
Classical Solutions ◽  
Computational Domain ◽  
Solution Domain ◽  
Differential Formulation

This paper proposes an efficient technique to solve the electromagnetic scattering problem, in the near zone of scatterers illuminated by external fields. The technique is based on a differential formulation of the Helmholtz equation discretized in terms of a finite element method (FEM). In order to numerically solve the problem, it is necessary to truncate the unbounded solution domain to obtain a bounded computational domain. This is usually done by defining fictitious boundaries where absorbing conditions are imposed, for example by applying the perfect matching layer (PML) approach. In this paper, these boundary conditions are expressed in an analytical form by using the Dirichlet-to-Neumann (DtN) operator. Compared to classical solutions such as PML, the proposed approach based on the DtN: (i) avoids the errors related to approximated boundary conditions; (ii) allows placing the boundary in close proximity to the scatterers, thus, reducing the solution domain to be meshed and the related computational cost; (iii) allows dealing with objects of arbitrary shapes and materials, since the shape of the boundary independent from those of the scatterers. Case-studies on problems related to the scattering from cable bundles demonstrate the accuracy and the computational advantage of the proposed technique, compared to existing ones.

Electromagnetic scattering by a system of two parallel dielectric prolate spheroids

1990 ◽  
Vol 68 (4-5) ◽  
pp. 376-384 ◽  
Author(s):  
M. F. R. Cooray ◽  
I. R. Ciric ◽  
B. P. Sinha
Keyword(s):  
Electromagnetic Wave ◽  
Incident Wave ◽  
Electromagnetic Scattering ◽  
Scattered Field ◽  
Plane Electromagnetic Wave ◽  
Angle Of Incidence ◽  
Algebraic Equations ◽  
Column Matrix ◽  
Prolate Spheroids ◽  
Expansion Coefficients

An exact solution to the problem of scattering of a plane electromagnetic wave by two dielectric prolate spheroids with parallel major axes is obtained by expanding the incident, scattered, and transmitted electric and magnetic fields in terms of an appropriate set of vector spheroidal eigenfunctions. The incident wave is considered to be a monochromatic, uniform plane electromagnetic wave of arbitrary polarization and angle of incidence. The boundary conditions are imposed by expressing the electromagnetic field scattered by one spheroid in terms of the spheroidal coordinates attached to the other, using the translational addition theorems for vector spheroidal wave functions. The column matrix of the total transmitted and scattered field-expansion coefficients is equal to the product of a square matrix, which is independent of the direction and polarization of the incident wave, and the column matrix of the known incident field-expansion coefficients. The solution of the associated set of algebraic equations gives the unknown transmitted and scattered field-expansion coefficients. Even though the problem is formulated in general, the numerical results are presented for the bistatic and backscattering cross sections of two lossless prolate spheroids with various axial ratios and center-to-center distances.

scholarly journals Terahertz Signal Generation in 1-D Photonic Crystals

2004 ◽  
Vol 14 (3) ◽  
pp. 39-49
Author(s):  
M. Torres-Cisneros ◽  
J. W. Haus ◽  
L. A. Aguilera-Cortés ◽  
R. Guzmán-Cabrera ◽  
R. Castro-Sánchez ◽  
...  
Keyword(s):  
Field Enhancement ◽  
Tunable Laser ◽  
Defect Mode ◽  
Normal Incidence ◽  
Numerical Results ◽  
Thz Radiation ◽  
Angle Of Incidence ◽  
Converted Signal ◽  
Laser Sources ◽  
Down Conversion

Theoretical and numerical results are presented to assure that a tunable, narrow-band, coherent THz radiation source can be based on parametric down-conversion in aphotonic crystal. Our proposal is based on down-conversion mixing and a local-field enhancement mechanism that is available by tuning each of the two driving laserfields either to band-edge or to a defect mode in the band gap. The frequency of the down-converted signal can be tuned by intersecting two non co-linear laser sources. The polarizations are degenerate at normal incidence and have sub-THz down-conversion maximum. For aspecific sample geometry we show that by changing the angle of incidence of one tunable laser to 30 degrees the THz frequency is about11.5 THz for p-polarization and 3.5THz for s-polarization, since the angle-dependent transmission spectrum is different for p- and spolarizations.The peak conversion efficiency for both polarizations is enhanced by over two orders of magnitude. Finally we also introduce some preliminary experimental results which agree with the numerical results we present here.

scholarly journals Far-field to Near-field Data Relations for the Inverse Electromagnetic Scattering Problem

2021 ◽  
pp. 22-28
Author(s):  
Arnold Abramov ◽  
Yutao Yue
Keyword(s):  
Electromagnetic Scattering ◽  
Field Data ◽  
Near Field ◽  
Scattering Problem ◽  
Optimization Procedure ◽  
Field Measurements ◽  
The Other ◽  
Far Field ◽  
Dielectric Cylinder ◽  
Material Parameters

This paper considers (in general form) the problem of recovering information (size and material parameters) about the scattering object from far-field measurements. The order of solution and functions of each equation for the fields inside and outside the scattering object are discussed. Using well-known mathematical theorems, a simple equation has been derived that connects the far-field data on one side to the near-field data on the other side. Consequently, this equation has been used in an optimization procedure to find the parameters of the dielectric cylinder.

Electromagnetic scattering by a lossy dielectric-coated elliptic cylinder

2003 ◽  
Vol 81 (5) ◽  
pp. 771-778 ◽  
Author(s):  
A -K Hamid ◽  
M I Hussein
Keyword(s):  
Electromagnetic Wave ◽  
Electromagnetic Scattering ◽  
Scattered Field ◽  
Wave Scattering ◽  
Elliptic Cylinder ◽  
Numerical Results ◽  
Dielectric Constants ◽  
Mathieu Functions ◽  
Electromagnetic Wave Scattering ◽  
Lossy Dielectric

The problem of electromagnetic wave scattering by a lossy dielectric-coated elliptic cylinder is analyzed using elliptic waves expressed in terms of complex Mathieu functions. Numerical results are obtained for the scattered field in the far zone for different axial ratios, lossy dielectric constants, and angles of incidence. The numerical results show a significant change in backscattering echo due to the lossy dielectric coating. PACS No.: 42.25.Fx

On the scattering of two-dimensional elastic point sources and related near-field inverse problems for small discs

2009 ◽  
Vol 139 (4) ◽  
pp. 719-741
Author(s):  
C. E. Athanasiadis ◽  
G. Pelekanos ◽  
V. Sevroglou ◽  
I. G. Stratis
Keyword(s):  
Scattered Field ◽  
Near Field ◽  
Scattering Problem ◽  
Two Dimensions ◽  
Point Sources ◽  
Circular Disc ◽  
Field Pattern ◽  
Far Field ◽  
Field Patterns ◽  
Direct Scattering

The problem of scattering of a point-generated elastic dyadic field by a bounded obstacle or a penetrable body in two dimensions is considered. The direct scattering problem for each case is formulated in a dyadic form. For two point sources, dyadic far-field pattern generators are defined and general scattering theorems and mixed scattering relations are presented. The direct scattering problem for a rigid circular disc is considered, and the exact Green function and the elastic far-field patterns of the radiating solution in the form of infinite series are obtained. Under the low-frequency assumption, approximations for the longitudinal and transverse far-field patterns of the scattered field are obtained, in addition to an asymptotic expansion for the corresponding scattering cross-section. A simple inversion scheme that locates the radius and the position of a rigid circular disc, which is based on a closed-form approximation of the scattered field at the location of the incident point source, is proposed.

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