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Scattering from a grounded chiral slab with rough interface is studied using perturbation theory. A system of equations for zeroth and higher order solution is written, which can be solved to get c...

An extension of the problem of reflection from a flat dielectric-chiral interface is presented. A dielectric-chiral rough interface is assumed and scattered field is calculated using small perturba...

The investigation of core-shell nanoparticles has been greatly exciting in biomedical applications, as this remains of prime importance in targeted drug delivery, sensing, etc. In the present work, the polarizability and scattering features of nanoparticles comprised of nano-sized dielectric/metallic core-shell structures were investigated in the fractional dimensional (FD) space, which essentially relates to the confinement of charged particles. For this purpose, three different kinds of metals&mdash, namely aluminum, gold and silver&mdash, were considered to form the shell, having a common silicon dioxide (SiO2) nanoparticle as the core. It is noteworthy that the use of noble metal-SiO2 mediums interface remains ideal to realize surface plasmon resonance. The core-shell nanoparticles were considered to have dimensions smaller than the operating wavelength. Under such conditions, the analyses of polarizability and the scattering and absorption cross-sections, and also, the extinction coefficients were taken up under Rayleigh scattering mechanism, emphasizing the effects of a varying FD parameter. Apart from these, the tuning of resonance peaks and the magnitude of surface plasmons due to FD space parameter were also analyzed. It was found that the increase of FD space parameter generally results in blue-shifts in the resonance peaks. Apart from this, the usage of gold and silver shells brings in fairly large shifts in the peak positions of wavelengths, which allows them to be more suitable for a biosensing purpose.

In this paper, near zone scattering properties of a perturbed perfect electromagnetic conductor (PEMC) cylinder are observed using the perturbation theory (PT). The analytical solution of the scattered field is obtained for both the transverse electric (TE) and transverse magnetic (TM) polarizations of the incident field. The perturbed cross section is generated considering the limits imposed by the PT. The effect of perturbations on the co and cross polarized components of the scattered field from a perturbed PEMC cylinder is observed and compared with the reference scattered field from the circular PEMC cylinder. In particular, the distinctions due to perturbations are observed in the forward and backward scattering. The forward scattering deviates more than the backward scattering. Also, the effect of perturbations for the TE polarization is more evident. The variations in the co and cross polarized scattering are also noted by changing the value of the admittance of the PEMC cylinder.

An arbitrary shaped scatterer is often modeled as a canonical structure while solving an electromagnetic boundary value problem. This approach approximates the boundary to provide complex analytical solutions. However, most real life structures do not have canonical or regular boundaries. Determining an analytical solution of electromagnetic scattering problem is quite a tedious task, especially for random geometries. This work proposes a method to compute the scattering statistics of a random cylinder. A formulation is developed to determine the probability density function (pdf) of scattering cross section, σ T , from the statistics of random cylinder's radius. This approach eliminates the need to actually solve an electromagnetic scattering problem. The optical theorem is employed to estimate the pdf of σ T from the pdf of lateral width. The proposed results are found in good agreement with the numerically simulated results.

Scattering from a perfect electric conducting cylinder with random radius buried below a half space dielectric homogenous interface is studied. The cylindrical wave scattered by cylinder is expanded in terms of plane wave spectrum. Small perturbation method is used to study the interaction of each plane wave with the interface. The zeroth order term yields solution for a flat interface, whereas scattering from a rough surface is given by first-order term. Results are obtained for both TM and TE polarizations. Analytical expressions of the average scattered field are obtained and verified using numerical evaluation. Different scattering scenarios are simulated by varying the distribution of the radius. It is observed that average scattering cross section of an ensemble with normal/uniform distribution is almost equal to that of a cylinder with mean radius.

A general theoretical formulation is done to calculate the field scattered by perfect electromagnetic conductor (PEMC) cylinder coated with anisotropic plasma material. It is buried below a slightly rough surface. Spectral plane wave representation of fields and small perturbation method are used to calculate multiple reflections between coated cylinder and rough surface. To validate the present formulation, scattered field from a PEMC cylinder coated with double negative (DNG) material is obtained from the present formulation. Scattering pattern of non coated PEC/PEMC cylinder or coated with isotropic material can also be obtained by the proper selection of physical parameters such as anisotropy, admittance of PEMC cylinder and permittivity of hosting medium. Analytical expressions of scattered field for a sinusoidal rough surface are given along with their physical interpretation to get a good insight. Effect of geometrical and physical parameters on scattering pattern is observed.

Scattering from a perfect electromagnetic conductor (PEMC) rough surface has been considered. PEMC does generalize perfect electric conductor (PEC) and perfect magnetic conductor (PMC). In contrast to PEC rough surface, cross-polarized component of the scattered field also exists. Small perturbation method is applied to evaluate co- and cross-polarized scattered fields. The zeroth-order solution corresponds to flat case while first-order term gives the contribution from the surface perturbations. The results reduce to that of the PEC flat/rough surface as , where M is the admittance parameter which characterizes the PEMC. The incoherent bi-static co- and cross-polarized scattering coefficients of a random rough surface are given. As an example, the case of a rough surface with sinusoidal profile is considered and the expressions for co- and cross-polarized filed components are reported.

Spectral plane wave representation of fields (SPRF) is applied to evaluate the scattered-transmitted field from a chiral cylinder buried beneath a flat/rough interface. Small Perturbation Method is used to evaluate rough surface scattering. An effort has been done to validate the results by making a comparison with the previously available results. Effect of surface period, chirality and size of the cylinder on scattered field is observed. It is noted that radar cross section (RCS) is significantly reduced for chiral objects buried beneath the flat interface. The same effect is observed in case of rough interface.

In this paper, near and far zone fields scattered from a perfect electromagnetic conductor (PEMC) cylinder coated with complex conjugate material (CCM) and buried below a sinusoidal rough surface is studied. Multiple reflections between the rough surface and the cylinder are evaluated with the help of perturbation theory applied on the plane wave spectrum representation of the cylindrical scattered field. Scattering from CCM coated cylinder is compared with that of a dielectric coated cylinder. Both the CCM and the dielectric material have same refractive index. Difference between the scattered fields is observed due to different impedance of the coating material. Near zone back scattering and forward scattering patterns are very insightful to pronounce the distinctions between the CCM and dielectric coating. It is also noted that for transverse electric (TE) polarized incident field, the forward scattering for CCM and dielectric coated cylinders differs significantly from each other. It is possible to achieve scattering maximization with CCM coating. Moreover, the effects of roughness and the admittance of the PEMC core are also noted on the scattering.

Perturbation theory (PT) is used to calculate the scattered field from a slightly perturbed cylinder for both transverse magnetic (TM) and transverse electric (TE) polarized incidence fields. A relation between the PT and the model for random cylinder (RC) generation is developed which is important for the PT to remain valid during the numerical simulations. The scattered field expressions obtained using the PT are verified using the result obtained by method of moments (MoM). The solution obtained by using the PT is more efficient in terms of simplicity and computational time. The scattering cross section is analyzed by varying the perturbation parameter B and the parameter describing the RC generation N . It is noted that both B and N controls the roughness of the cylinder and hence affect the scattering pattern. The scattered field for TE polarized incident field is more sensitive to the change in B and N than TM case.

A numerical solution is presented for electromagnetic scattering from a random cross-section of a cylinder placed inside a dielectric half-space. Assumed that a plane wave of known parameters is incident from the half space. The incident electric field of an electromagnetic plane wave is parallel to the z-axis of the random cylinder. The method of moment is employed to obtain surface currents and Electric field integral solution is used to obtain the scattered field. The problem consists of two regions, the observer located in the free space region above from interface and the second region is an underground region where the random cylinder is placed. In the whole scenario, the medium is considered as homogeneous and lossless. The average scattered field is observed by varying different parameters for realization. To diversify the solution, COMSOL Multiphysics® and Matlab is used for simulations to investigate backscattered field involving transverse electric (TE) and transverse magnetic (TM) polarizations.

The reduction in radar cross section (RCS) of a perfect electric conductor (PEC) cylinder coated with chiral media buried below a sinusoidal surface is investigated. Spectral plane wave representation of field (SPRF) is used to account for the interaction of buried cylinder with the sinusoidal surface. Small perturbation method (SPM) is used to observe scattering from the sinusoidal surface. Different scattering scenarios are simulated by changing chirality and thickness of coating layer. It is observed that co polarized RCS is significantly reduced for some values of chirality. The behavior of the scattering coefficients is very useful to understand the dependence of RCS reduction on chirality.

Scattering of electromagnetic wave from a DNG coated perfect electromagnetic conductor (PEMC) cylinder buried below a slightly rough sinusoidal surface is investigated. This is a generalization of different earlier solved such problems involving PEC/PEMC coated/non-coated cylinder buried below flat/rough surface. The initial reflected and transmitted field from the sinusoidal surface are evaluated using Small Perturbation Method (SPM). All the interactions between the object and the sinusoidal surface have been taken into account using spectral plane wave representation of fields (SPRF). The effect of geometrical and physical parameters on the scattering pattern is observed.

The scattering of left circularly polarized wave from a perfectly electric conducting (PEC) rough surface in isotropic chiral media is investigated. Since a slightly rough interface is assumed, the solution is obtained using perturbation method. Zeroth-order term corresponds to solution for a flat interface which helps in making a comparison with the results reported in the literature. First-order term gives the contribution from the surface perturbations, and it is used to define incoherent bistatic scattering coefficients for a Gaussian rough surface. Higher order solution is obtained in a recursive manner. Numerical results are reported for different values of chirality, correlation length, and rms height of the surface. Diffraction efficiency is defined for a sinusoidal grating.

Electromagnetic scattering from a topological insulator (TI) cylinder buried beneath a rough surface is considered. To account for the interactions of the scattered field and the rough surface, spectral plane wave representation of fields is used along with small perturbation method. Both time-reversal symmetry TI cylinder and time-reversal symmetry broken TI cylinder are considered to evaluate the scattered-transmitted field above the rough surface for different values of the periods of the rough surface and the size of the object. It is observed that co- and cross-polarized field components show a maximum before the time-reversal symmetry is broken. The co-polarized component remains almost constant while the cross-polarized component decreases for time-reversal symmetry broken case.

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 r...

Analytical solution of vector wave equation describing the scattering of electromagnetic plane waves from an infinitely long circular chiral cylinder placed in another chiral metamaterial is presented. Cylindrical vector wave functions are used to express the fields both inside and outside the circular cylinder. The unknown are determined by applying the appropriate boundary conditions at the cylindrical interface. The numeric results are presented taking different combinations of metamaterials for inner and outer mediums of the cylinder. For this purpose chiral and/or chiral nihility cylinder placed in chiral and/or chiral nihility mediums are considered. Extreme cases of permittivity and permeability corresponding to PEC and PMC cylinder are also considered.

A mathematical model of random cylinder is given to facilitate realization of a single random cylinder and study its electromagnetic scattering properties. The proposed model is very versatile as cylinders with cross sections varying from circular to rough (noise like) can be easily generated. Statistical properties of the radius of random cylinder are analytically determined. Electromagnetic field scattered from a smooth random cylinder is obtained using Moments Method. Ensemble averages of the scattered field in all directions and total scattering cross section are obtained. The optical theorem test shows that the solution obtained in this paper is better than the earlier proposed solutions.

Scattering by a perfectly conducting strip which is buried in an infinite grounded dielectric layer is considered. It is assumed that the strip is far away from interfaces of the grounded dielectric layer. This assumption is utilized to simplify the work by considering that the scattered field, which is reflected more than once by any interface or reflected by both the interfaces of grounded dielectric layer, has no interaction with the buried strip. Dominant contribution of the reflected scattered field which interacts with the strip is calculated asymptotically, for large separation of the strip from boundaries of the grounded dielectric layer. Far-zone field expression, for region above the grounded dielectric layer, is derived taking into account the effects of interaction of reflected scattered field with the strip. This expression is derived in a general form which can be applied to any arbitrary cylindrical obstacles. Some numerical results are given for the case of perfectly conducting circular cy...