Download or read book Electromagnetic Scattering by a Three-dimensional Object Composed of an Orthorhombic Dielectric-Magnetic Medium Endowed with Magnetoelectric Gyrotropy written by Hamad Alkhoori and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The main purpose of this research is to investigate scattering of an electromagnetic field by a three-dimensional nonspherical object (e.g, spheroid, ellipsoid, etc.) composed of an orthorhombic dielectric-magnetic medium endowed with magnetoelectric gyrotropy. The relative permittivity dyadic must be a scalar multiple of the relative permeability dyadic, and the constitutive principal axes can be arbitrarily oriented with respect to the shape principal axes.Scattering by nonspherical objects fits many realistic situations. Furthermore, the interplay of shape anisotropy and medium anisotropy as well as their simultaneous effect on scattering may provide useful features that are not exhibited by objects composed of isotropic mediums. Possible examples include low scattering and high absorption, which can be useful in designing structures for stealth applications. I used the extended boundary condition method (EBCM) to study electromagnetic scattering by a three-dimensional object composed of the chosen medium. Known vector spherical wave functions were used to represent the fields in the surrounding matter-free space. After I derived closed-form expressions of the vector spherical wave functions for the chosen medium (available in coordinate-free form but not in closed-form), the internal fields were represented as superpositions of those vector spherical wave functions. Application of the EwaldOseen extinction theorem and the Huygens principle then yielded a transition matrix to relate the unknown scattered field coefficients to the known incident field coefficients.Numerical results were obtained for scattering of a plane wave by an ellipsoid composed of the chosen medium. The scattering, absorption, and extinction efficiencies were calculated thereby in relation to: (i) the shape of the object, (ii) the constitutive-anisotropy parameters of the permittivity and permeability dyadics, (iii) the magnetoelectric-gyrotropy vector, and (iv) the orientation of the constitutive principal axes with respect to the shape principal axes.A study on the shape of the object and the constitutive-anisotropy parameters revealed that the total scattering efficiency can be smaller than the absorption efficiency for some configurations of the incident plane wave but not necessarily for others. The shape of the object has a stronger influence on the total scattering efficiency than on the absorption efficiency. Even though the ellipsoid is not necessarily a body of revolution, it is anisotropic, and it is not impedance matched to free space, the backscattering efficiency can be minuscule but the forward-scattering efficiency is not.The effects of the magnetoelectric-gyrotropy vector can be envisioned in that both the total scattering and forward-scattering efficiencies are maximum when the plane wave is incident in a direction coparallel (but not antiparallel) to the magnetoelectric-gyrotropy vector, and the backscattering efficiency is minimum when the magnetoelectric-gyrotropy vector is parallel to the incidence direction. The total scattering and forward-scattering efficiencies are maximum when the incidence direction is parallel to the largest semi-axis of the ellipsoid if the incidence direction is coparallel (but not antiparallel) to the magnetoelectric-gyrotropy vector. From these results, I concluded that Lorentz nonreciprocity in an object is intimately connected to the shape of that object in affecting the scattered field.The orientation of the constitutive principal axes with respect to the shape principal axes has a noticeable effect on the total scattering and absorption efficiencies as the electrical size increases. Furthermore, the polarization state of the incident plane wave has a more visible effect on the total scattering and absorption efficiencies for ellipsoids compared to spheres. As an application that involves the chosen medium of this research, I determined sufficient conditions for zero backscattering from an object composed of the chosen medium and suspended in an isotropic dielectric-magnetic medium endowed with magnetoelectric gyrotropy by an analysis of the transition matrix. The elements of the transition matrix must satisfy certain conditions for zero backscattering. Numerical results obtainedthereby showed that the sufficient set of three zero-backscattering conditions are as follows: (i) The object is a body of revolution with the incident plane wave propagating along the axis of revolution. (ii) The impedances of both mediums are equal. (iii) The magnetoelectric-gyrotropy vectors of both mediums are aligned along the axis of revolution, whether or not both magnetoelectric-gyrotropy vectors are co-parallel.