Nicola Tedeschi

Electromagnetic Scattering by a Metallic Cylinder Buried in a Lossy Medium With the Cylindrical-Wave Approach

The 2-D electromagnetic scattering of a plane wave by a perfectly conducting cylinder buried in a lossy medium is presented. The problem of reflection and transmission of both the plane wave and the cylindrical wave at the interface with a dissipative medium has been faced, taking into account the general case of inhomogeneous waves. The scattering problem has been solved with the cylindrical-wave approach. The theoretical solution has been numerically implemented in a Fortran code, and the numerical results have been compared with both the literature and simulations with a commercial software.

On the electromagnetic power transmission between two lossy media: discussion

An overview of the problems involved in the study of electromagnetic power transmission between lossy media is presented. Starting from the well-known problem of the transmission at a dielectric-conductor interface, the different representations of the complex propagation vector of the plane waves are introduced. Analytical expressions to convert from one formulation to the other are obtained. Moreover, the transmission of a plane wave at the interface between two lossy media is taken into account. An explanation of the strange behavior of the transmitted wave is developed by means of power considerations. Finally, the interesting effect of the parallel-attenuated transmitted wave is presented, and its properties as a function of the incident phase vector amplitude are deduced.

On the perfectly matched layer and the DB boundary condition.

In this paper, we consider a particular uniaxial material able to achieve the DB boundary condition. We show how, for particular transverse electromagnetic properties, this material behaves like a perfectly matched layer (PML). Moreover, we find that, with an approximation, the material becomes passive, i.e., loses the active part of the permittivity and of the permeability typical of a PML. In this case, the uniaxial medium becomes realizable as a particular absorbing metamaterial. We present simulations with both guided and free-space waves to show the absorbing behavior of the proposed material.

Spectral domain method for the electromagnetic scattering by a buried sphere

A rigorous method to analyze the electromagnetic scattering of an elliptically polarized plane wave by a sphere buried in a dielectric half-space, is presented. The electric field components of the incident and the scattered monochromatic plane waves are expanded in series of vectorial spherical harmonics, with unknown expansion coefficients. The scattered-reflected and scattered-transmitted fields are computed by exploiting the plane-wave spectrum of the scattered field, considering the reflection and transmission of each elementary plane wave by the interface. The boundary-condition imposition leads to a linear system that returns the unknown coefficients of the scattered field. To achieve a numerical solution, a code has been implemented, and a truncation criterion for the involved series has been proposed. Comparisons with the literature and simulations performed with a commercial software are presented. A generalization of the method to the case of a short pulse scattered by a buried sphere is presented, taking into account the dispersive properties of the involved media.

Homogenization of a multilayer sphere as a radial uniaxial sphere: Features and limits

We consider a multilayer sphere with a fixed external radius and with an arbitrary number of layers as a possible realization of a radial uniaxial (RU) sphere. We start from the well-known quasi-static model for the polarizability of the multilayer sphere and, after a validation with a dynamic code previously presented, we try to understand the limits in which the multilayer sphere can be considered a RU sphere. We employ different techniques for layering the spheres and we find which of them is convenient in terms of convergence speed. Moreover, we deal with the case of plasmonic layers and we find some rules for the realization of the multilayer sphere in order to obtain the desired homogenized parameters. Finally, we present a study on the behavior of plasmon resonances of the multilayer sphere when the number of layers is increased.

Ultra-thin narrow-band, complementary narrow-band, and dual-band metamaterial absorbers for applications in the THz regime

In this paper, ultra-thin narrow-band, complementary narrow-band, and dual-band metamaterial absorbers (MMAs), exploiting the same electric ring resonator configuration, are investigated at normal and oblique incidence for both transverse electric (TE) and transverse magnetic (TM) polarizations, and with different physical properties in the THz regime. In the analysis of the ultra-thin narrow-band MMA, the limit of applicability of the transmission line model has been overcome with the introduction of a capacitance which considers the z component of the electric field. These absorbing structures have shown a wide angular response and a polarization-insensitive behavior due to the introduction of a conducting ground plane and to the four-fold rotational symmetry of the resonant elements around the propagation axis. We have adopted a retrieval procedure to extract the effective electromagnetic parameters of the proposed MMAs and we have compared the simulated and analytical results through the interference ...

Reflection and Transmission at the Interface With an Electric–Magnetic Uniaxial Medium With Applications to Boundary Conditions

The interface between an isotropic medium and a general uniaxial anisotropic medium is considered and the reflection coefficients are obtained. Their behavior in some particular cases is presented. A new boundary condition for the electromagnetic field is introduced. It requires the cancellation of both the electric and the magnetic fields along a generic direction. The realization of this boundary condition is proposed by means of a uniaxial medium: the properties of such medium are investigated. An interesting property of the reflection matrix is demonstrated, i.e., when the uniaxial medium is affinely isotropic and has the same impedance of the isotropic medium, the reflection matrix is proportional to a unitary matrix.

Deeply penetrating waves in lossy media

The incidence of an inhomogeneous plane wave on the interface between two lossy media is analyzed. The analytical expressions of the incidence angle of the phase vector, for which the transmitted wave has the phase or the attenuation vector parallel to the interface, are obtained. The transmitted wave with the attenuation vector parallel to the interface is physically interpreted, finding a wave in a lossy medium without attenuation away from the interface. The same effect appears at the interface between a lossless medium and a lossy one.

Electromagnetic inhomogeneous waves at planar boundaries: tutorial.

In this review paper, we summarize the fundamental properties of inhomogeneous waves at the planar interface between two media. We point out the main differences between the wave types: lateral waves, surface waves, and leaky waves. We analyze each kind of inhomogeneous wave, giving a quasi-optical description and explaining the physical origin of some of their properties.

Electromagnetic interaction with two eccentric spheres

In this paper, we consider the interaction of an electromagnetic field with two eccentric spheres. We propose a quasi-static approach in order to calculate the scattered field and the polarizability and the effective permittivity of the eccentric spheres. We analyze the behavior of the scattering parameters as a function of the dimension and position of the spherical inclusions. Moreover, we consider the case of plasmonic spheres and study the behavior of the plasmon resonances for different reciprocal positions of the two spheres.