Muhammad Arshad Fiaz

Scattering by a Circular Cylinder Buried Under a Slightly Rough Surface: The Cylindrical-Wave Approach

An analytical-numerical technique for the scattering problem of a plane wave by a cylinder buried under a rough surface, based on the Cylindrical Wave Approach, is presented. The rough deviations on the interface are dealt with by means of the Small Perturbation Method. Reflection and transmission coefficients are evaluated in a first order approximation, and fields are the sum of a zeroth-order solution, relevant to flat surface, and first-order perturbation fields, associated to the surface roughnesses. Numerical results are obtained through an exact evaluation of the spectral integrals, giving results both in near- and far-field regions, for the case of an interface with sinusoidal profile. The approach is validated through comparisons with the literature, and results showing the effect of geometrical and physical parameters on the scattered field are reported.

High-Frequency Expressions for the Field in the Caustic Region of a PEMC Cylindrical Reflector Using Maslov's Method

High frequency field expressions for a PEMC cylindrical reflector are derived using Maslovs method. These expressions are also valid in the vicinity of focal region of cylindrical reflector. Perfect electromagnetic conductor (PEMC) is a non-reciprocal generalization of both the perfect electric conductor (PEC) and perfect magnetic conductor (PMC).

Electromagnetic scattering by a circular cylinder buried below a slightly rough Gaussian surface

A two-dimensional beam is scattered by a cylinder buried below a slightly rough surface. The cylindrical wave approach is applied, i.e., cylindrical waves are employed as basis functions of the fields scattered by the cylinder. Moreover, a spectral representation of both the incident field and the cylindrical waves is used. Rough surface deviation is coped with by the first-order small perturbation method. Therefore, to a zeroth-order solution relevant to scattering in the case of a flat surface, a first-order approximation is superimposed. The theoretical approach has been implemented for a periodic surface with Gaussian roughness spectrum.

HIGH-FREQUENCY EXPRESSION FOR THE FIELD IN THE CAUSTIC REGION OF A PEMC GREGORIAN SYSTEM USING MASLOV'S METHOD

Method proposed by Maslov has been used, to remedy the problem of geometrical optics, for a two dimensional Perfect electromagnetic conductor (PEMC) Gregorian system. It generates an integral form of solution near the caustic that can be evaluated analytically/numerically, or with uniform asymptotic techniques. Away from the caustic it recovers the geometrical optics field. Numerical computations are made to calculate the field around the caustic of a Gregorian system.

Asymptotic solution for a scattered field by cylindrical objects buried beneath a slightly rough surface

The problem of scattering of electromagnetic waves from a set of cylindrical objects buried beneath a slightly rough surface is undertaken with the cylindrical wave approach as a method of analysis. The small perturbation method is used to compute the scattered field from a rough surface. Numerical results for a rough surface with a sinusoidal profile are obtained with asymptotic evaluation.

Reflection from Perfect Electromagnetic Conductor (PEMC) Boundary Placed in Chiral Medium

Using duality transformations introduced by Lindell and Sihvola, reflected field from a perfect electromagnetic conductor interface placed in chiral medium has been determined. Transformations take reflected field from a PEC interface placed in chiral medium as known problem.

Scattering of two-dimensional field from a PEMC cylinder buried beneath slightly rough surface

The problem of electromagnetic scattering of two-dimensional field by a perfect electromagnetic conducting cylinder buried beneath slightly rough surface has been considered. The solution is obtained using the spectral, plane wave representation of the fields together with perturbation method to deal with the rough deviations on the interface. Asymptotic evaluation of the spectral integrals has been done to obtain results for both co- and cross-polarized scattered-transmitted fields. To validate the theory, the case of rough surface with sinusoidal profile is simulated. A rough surface with Gaussian roughness spectrum has also been considered. The illuminated area is limited by the use of Gaussian beam incidence. Different scattering scenarios are implemented, varying the correlation length of the surface and the radius of the cylinder. Studies are done to determine both co- and cross-polarized scattered fields that can be useful in the detection of the material properties of the buried object below the rough surface.

Scattering of electromagnetic plane wave from a low contrast circular cylinder buried in non-integer dimensional Half Space

The objective of this paper is to study ‘scattering of electromagnetic waves from a dielectric circular cylinder buried in non-integer dimensional dielectric half-space’. To achieve this objective first two auxiliary problems are solved. The problem of reflection and transmission of electromagnetic waves for an interface between two dielectric mediums is studied first. The dimension normal to the interface is non-integer. Secondly, radiated fields from a buried current carrying line source in an non-integer dimensional half-space have been derived. By using the results of these auxiliary problems, scattering from a low contrast dielectric cylinder buried in non-integer dimensional half-space is studied using perturbation technique. Special cases are also considered when one of the two or both half-spaces are taken to be of integer dimension

Electromagnetic behavior of a planar interface of non-integer dimensional spaces

Abstract Reflection and transmission properties of a planar interface of two non-integer dimensional (NID) half spaces are studied. It is assumed that dimensions of both half spaces normal to the interface are non-integer. Both half spaces are distinguished from each other by non integer dimensions rather than wavenumbers. A plane wave has been taken as source of excitation. It is observed that non integer dimensions are also the factors controlling the reflection and transmission properties of the interface. Special cases are also considered when one or neither of the two half-spaces are NID.

Scattering from topological insulator circular cylinder buried in a semi-infinite medium

The problem of electromagnetic scattering of a plane wave from a topological insulator (TI) cylinder buried beneath a flat interface is undertaken with the method of analysis based on spectral plane wave representation of fields. Saddle point method is employed to evaluate the involved spectral integrals serving as basis functions in the representations of scattered-reflected and scattered-transmitted fields. The distinctions between the scattering pattern for time reversal symmetry TI cylinder and that of time reversal symmetry broken TI cylinder are pronounced. Results are validated through the comparison with the previously available results.