Scattering Of Electromagnetic Waves Research Articles

Scattering of Electromagnetic Waves With Orbital Angular Momentum on Metallic Sphere

In this letter, theory concerning scattering of electromagnetic (EM) waves with orbital angular momentum (OAM) is presented, in which a metallic sphere illuminated by OAM waves is adopted to simplify the study. Based on the series expansion and the physical optics (PO) methods, expressions of incident and scattered OAM waves are obtained. To get the expansion coefficients of the scattered fields, boundary conditions and Debye potentials are applied to establish the relationship between incident and scattered fields. Besides, a full EM wave simulation of the scattered field has been accomplished by the computer simulation technology (CST), the measurement of scattered field is done in an anechoic chamber. The simulated results are in good consistency with numerical calculations, demonstrating the interaction between the OAM EM waves and the metallic target sphere effectively. This letter also paves the way for research on scattering of complex targets of OAM waves, and for future studies on target detection.

Scattering of electromagnetic waves from a thin triangular dielectric disk

An analytic theory for the scattering of electromagnetic waves from a thin dielectric triangular disk is presented. The proposed theory is based on the Koh–Sarabandi approximation for the electromagnetic wave scattering from a thin dielectric disk along with the spectral representation of the dyadic Green's function. The validity of the proposed formulation is justified by comparing it with the numerical method such as method of moments. For completeness, the scattering cross sections of a triangular disk for horizontal and vertical incident polarizations are compared with their respective scattering cross sections of elliptical, circular, semi-circular and square disks having same electromagnetic and geometrical parameters. It is studied that the back scattering cross sections for a low loss Gallium Arsenide triangular disk at a specific incidence angle can be made almost zero for both types of incident polarizations. This type of almost zero back scattering has applications in the stealth technology and remote sensing.

On the Scattering of Electromagnetic Waves by Cylindrical Bodies with Non-Coordinate Boundaries

Different variants of the problem of diffraction of plane electromagnetic wave by the cylindrical body are constructed and researched in the work. These problems are reduced to infinite sets of linear algebraic equations. The conductive bodies and dielectric bodies with thin conductive bands on the non-coordinate boundary are considered. The results of the computational experiment are presented.

Investigation on THz EM Wave Scattering From Oil-Covered Sea Surface: Exploration for an Approach to Probe the Thickness of Oil Film

In this article, a theoretical study is carried out to seek an approach to remotely measure the thickness of the oil film. It is known that it is difficult to probe the oil thickness using a microwave radar due to the fact the dielectric constant of oil is very small compared with seawater for microwave frequencies. While in the range of terahertz (THz) electromagnetic (EM) wave frequency, the dielectric constants of oil and seawater are comparable, resulting in the THz EM fields scattered from the air–oil interface and those from the oil–water interface can produce constructive and destructive interference with the variation in the oil film thickness. Based on this principle, the sensitivity of the THz EM wave to the oil thickness is investigated in this work. First, the oil–seawater two-layer medium is equivalent to a single-layer medium by an equivalent dielectric constant model. Then, the THz EM scattering from the oil-covered sea surface is simulated using the first-order small slope approximation method (SSA-1) and the obtained equivalent dielectric constant. Meanwhile, the influences caused by the damping effect of the oil film, the reduction for friction velocity, and the change in equivalent permittivity on the normalized radar cross section (NRCS) are analyzed. The numerical results show that the NRCSs of THz frequencies are more sensitive to the change in oil thickness than that of microwave frequencies. This property makes the THz EM wave have the potential to probe the thickness of the oil film.

Correction to “scattering of electromagnetic plane wave by a PEC strip in homogeneous isotropic chiral medium”

ABSTRACT The aim of this paper is to correct errors of a published study [Afzaal M, Syed A, Imran A, et al. Scattering of electromagnetic plane wave by a PEC strip in homogeneous isotropic chiral medium. Journal of Electromagnetic Waves and Applications. 2014;28(8):999–1010]. The investigation is a prominent and attractive subject in the field of electromagnetic scattering that has studied the electromagnetic scattering from a PEC strip located in the chiral medium; but unfortunately, the errors cause that readers be confused and cannot understand the work. Also, the figures of the paper are incorrect because of the basic errors. The formulation of this investigation is validated by a previously published paper [Davoudabadifarahani H, Ghalamkari B. Analytical solution of electromagnetic scattering by PEMC strip embedded in the chiral medium. Engineering Analysis with Boundary Elements. 2020;113:1–8].

Scattering and Emission of Electromagnetic Waves From Random Layered Media With Random Rough Interfaces: A Partially Coherent Cascading Approach

A partially coherent approach for computing the electromagnetic response of a layered medium having random rough interfaces and a random dielectric profile is presented as an alternative to the full-wave solution of the problem. The statistical nature of this problem, in particular, the random dielectric profile, introduces randomness in the phase of the electromagnetic field such that the field loses its phase coherency after traveling in the layered medium for a few correlation lengths of the permittivity. In this situation, there is a coherency length within which a coherent solution of Maxwell’s equation is required. For the distances beyond this coherency length, a combined coherent–incoherent cascading approach can be applied to reduce the computational complexity of the problem. The coherent response of each “block” within the medium (with a length approximately the coherency length) can be cascaded incoherently ignoring the phase response without losing accuracy. Cascading equations for block bistatic scattering are applied, and solutions of the equivalent block parameters are obtained by iteration up to the second order of multiple scattering. The proposed method is described in this article, and the numerical results are shown to compare the proposed cascading approach with the results obtained from the fully coherent solution.

Electromagnetic Wave Propagation, Radiation, and Scattering: From Fundamentals to Applications [Book Review

Electromagnetic Wave Propagation, Radiation, and Scattering: From Fundamentals to Applications [Book Review

Scattering of electromagnetic waves by an aggregate of gyromagnetic and dielectric spheres: Magnetic tuning of Fano resonances

We study the interaction of electromagnetic waves with a cluster composed of gyromagnetic and dielectric spheres. We expand the electromagnetic fields in terms of the vector multipole fields and relate the expansion of the scattered field to that of the incident field. We apply this generalized multisphere Mie theory to dimers and hexamers containing one dielectric sphere and similar gyromagnetic spheres. We observe multiple Fano resonances in the extinction, circular extinction, and optical activity spectra of the oligomers. Fano resonances can be engineered by adjusting the geometrical and structural parameters of the system. More importantly, Fano resonances can be dynamically tuned by an external magnetic field. A Fano resonance frequency shift as large as 0.5--1 GHz for a magnetic field increase of $200\phantom{\rule{0.28em}{0ex}}\mathrm{G}$ is achievable.

Scattering of Electromagnetic Wave by system of core/shell microsphere and nanoparticle

The paper deals with the scattering of an electromagnetic plane wave by a system of core/shell microspheres and a single nanoparticle placed outside the spheres. Backscattering intensity perturbation caused by the nanoparticle was studied, and it was found that the position of the inner sphere can be used as a new effective tool to both detect a particle and to determine its size. The system of core/shell microspheres provides a longer particle detection distance compared with a single sphere system. It is shown that the maximum value of the perturbation of backscattering is reached at the interspherical distance corresponding to the maximal energy of the electromagnetic wave concentrated in the vicinity of the nanojet.

ИСПОЛЬЗОВАНИЕ МЕТОДА ДИАГРАММНЫХ УРАВНЕНИЙ ДЛЯ АНАЛИЗА ДИФРАКЦИИ НА МАЛЫХ РАССЕИВАТЕЛЯХ

Scattering of electromagnetic waves by small particles is an important key task of diffraction theory. This is due to a wide range of practical applications of the effects associated with the scattering of electromagnetic waves by particles, small in com-parison with the wavelength. From the moment of the appearance of the first papers devoted to this subject and up to the present, the most used mathematical model used in solving the problem of scattering by small bodies is the dipole approximation (Rayleigh approximation). This approach is described in sufficient detail for particular cases of scattering by balls and ellipsoids, when the solution of the auxiliary electrostatic problem can be obtained in explicit form. Note that the solution of the problem in the electrostatic approximation in the general case, in itself, is quite complicated and time-consuming compared with the solution of the original wave problem. Existing methods for solving it have a number of fundamental limitations. In this paper, we developed a technique based on the use of the method of Pattern Equations Method (PEM), first proposed in 1992. In a significant number of publications, it has been clearly demonstrated that PEM have important advantages over many alternative methods and are very effective in solving a wide class of problems. In constructing a new approach to the analysis of scattering by small bodies, we used the high convergence rate of the PEM established in our previous papers. Indeed, as shown in previous works of the authors of this article, to solve the problem of scattering by impedance bodies, whose characteristic size is comparable with the wavelength of the incident field, it suffices to take into account, depending on the polarization of the incident field, one to three terms in the Fourier decomposition of the scattering pattern. This circumstance made it possible to obtain explicit formulas for the integral scattering characteristics applicable to complex-shaped impedance scatterers. In this work, explicit formulas are obtained for the integrated scattering characteristics that are applicable to small, compared with the incident radiation wavelength, scatterers. A review is given of the application of an approximate methodology for calculating the integral scattering characteristics of small diffusers of arbitrary shape, in particular, thin dielectric cylinders, based on the use of PEM. As the above results show, the approximate relations obtained have sufficient accuracy in a wide range of problem parameters.

Method for Scattering of Electromagnetic Waves From the Human Body Based on Truncated Norton Surface Wave Approximation

The interaction of millimeter waves with lossy bodies is of interest for applications such as remote sensing, imaging, security screening, and military applications. A new approximate simulation method is proposed for the electromagnetic (EM) scattering of millimeter waves from lossy bodies. This truncated Norton surface wave approximation (TSWA) is based on the application of a generalized transition matrix that describes the excitation of Norton surface waves by point sources, which are placed at the body interface for homogeneous lossy materials. The interface is represented by overlapped square patches, which playing role of supports of spline basis functions. The patch size can be of the order of the incident wavelength or larger, enabling the number of variables to be reduced. The total scattered EM field is defined as a superposition of scattered waves from all patches. Verification was performed by comparing the results of simulations using the TSWA method with those of an exact EM solver. The TSWA method was also applied to simulate the multifrequency scattering from a whole human body using a multistatic array.

Scattering of Electromagnetic Waves on a Subwave Lattice of Square Strip Conductors

Simple formulas are obtained for calculating the scattering matrix of a plane electromagnetic wave incident normally on an infinite 2D lattice formed by square strip conductors and located at the interface of two dielectric media. For the first time, the vortex behavior of the electric field of the lattice was taken into account, which made it possible to repeatedly reduce the computation error at high frequencies. This is confirmed by the close agreement of the amplitude-frequency responses of the structure calculated by the formulas with the characteristics obtained by the numerical electrodynamic analysis of the 3D model when the lattice period is less than half the wavelength.

Рассеяние плоской электромагнитной волны кусочно-однородной линзой Люнеберга

Рассеяние плоской электромагнитной волны кусочно-однородной линзой Люнеберга

The Experimental Study of Electromagnetic Waves Scattering of Underlying Terrain in Centimeter and Millimeter Ranges

The results of sensing in various terrain types at centimeter and millimeter wavelength ranges of waves with horizontal polarization and small grazing angles are presented. Specific radar cross section and temporal and range correlation characteristics of the reflected signal are calculated.

Scattering of electromagnetic waves by a perfectly conducting half-screen at the interface of two different media: E-polarization

The interaction of electromagnetic waves with a perfectly conducting half-screen, which is residing between two media with different electromagnetic properties, is investigated for electric polarization. The diffracted fields, in two regions, are determined by using a relation between diffraction and scattered geometric optics waves. Additional terms are included in the diffracted waves in order to satisfy the boundary conditions in the interface. The behavior of the total field and its components are analyzed numerically.

Scattering of electromagnetic waves by a perfectly conducting wedge for grazing incidence

The diffraction phenomenon of electromagnetic waves by a perfect electric conductor and perfect magnetic conductor wedges is investigated for the grazing incidence. It is shown that the rigorous solution does not reduce to the correct diffraction fields when the angle of incidence is zero according to the one of the faces of wedge. A new expression is obtained by dividing the high-frequency asymptotic diffracted field expression into four parts. Some numerical results are given.

Scattering of electromagnetic waves by cylinder inside uniaxial hyperbolic medium.

We study electromagnetic wave scattering inside a hyperbolic medium by a circular cylinder. The hyperbolic medium's unique properties result in scattering behaviors that differ greatly from scattering by the same cylinder inside a positive isotropic medium. Incident wave polarization is preserved for all angles of incidence and the scattered waves have the same polarization in the far-field region. TM-polarized plane wave scattering is highly anisotropic. At any given frequency, the dielectric cylinder's scattering properties can vary from the Rayleigh regime, to the resonant regime, to the evanescent regime, by simply changing the angle of incidence. At a given angle, as a function of frequency, the scattering efficiency exhibits narrow resonant features associated with Fano interference. We also show that a magnetic cylinder's scattering can be suppressed. All of these effects stem from the hyperbolic medium's properties, as well as point to the interesting opportunities of tailoring scattering properties by controlling the surrounding medium.

Scattering of Electromagnetic Waves by Inhomogeneous Dielectric Gratings Loaded with Conducting Strips — Matrix Formulation of Point Matching Method —

We have proposed a new method for the scattering of electromagnetic waves by inhomogeneous dielectric gratings loaded with parallel perfectly conducting strips using the combination of improved Fourier series expansion method and point matching method. Numerical results are given for the transmitted scattered characteristics for TE and TM cases.

Рассеяние электромагнитной волны на структуре, состоящей из магнитодиэлектрического тела и тонких проводников

Рассеяние электромагнитной волны на структуре, состоящей из магнитодиэлектрического тела и тонких проводников

Scattering of electromagnetic waves by a perfect electromagnetic conductor half-screen

The diffraction of plane electromagnetic waves by a perfect electromagnetic conductor half-screen is investigated. The total geometrical optics fields are obtained by using the boundary conditions of a perfect electromagnetic conductor surface. A general relation is defined for the scattered fields in terms of waves by soft and hard surfaces. The total scattered field is derived by using this relation. Some numerical simulations are also given.