Study Of Electromagnetic Scattering And Reconstruction For Anisotropic Media

Evaluation of electromagnetic scattering by anisotropic media may be of interest inmany military and civil applications. The Finite-Difference Time-Domain (FDTD) method,General Propagation Matrix (GPM) method and Boundary Integral Method (BIM) areeffective schemes to deal with the scattering problems of an object containing anisotropicmedia. Main efforts are put on the scattering and inverse scattering problem of anisotropicmedia. These problems include the scattering properties of a cavities in conducting platefilled with anisotropic medium, the scattering and transmission properties of slits in aconducting plate filled with anisotropic medium, the scattering of anisotropic object andreconstruction the permittivity and permeability of anisotropic medium. Considering thecomplexity of the problem, we firstly study one-dimensional problems, then analyze two-and three-dimensional problems. Using kDB system and coordinate transform, the reflection coefficient andtransmission coefficient is computed when layered anisotropic medium is illuminated by aplane electromagnetic wave. With transformation formulas the constructive relation can betransformed from principal system to kDB system. We can obtain two characteristic wavesin kDB system, and then derive the characteristic waves in laboratory system bytransformation formulas. According to the boundary condition at interface the reflectioncoefficient of a layered anisotropic medium is deduced. Otherwise, we use GPM tocompute the reflection and transmission coefficient of loss anisotropic media. The stateequations and coupling matrix of transverse fields are constructed by Maxwell's curlequations in anisotropic medium. This method can conquer the difficulty of determiningthe wave vector in common case, and it can deal with the reflection and transmissionproblem of anisotropic media with arbitrary permittivity and permeability tensors. Using BIM and Generalized Network Formulation (GNF) the scattering by cavitiesand slits in a conducting plane are investigated. The problem for cavities or slits filled withisotropic media has been dealt with in publications. However, the problem for cavities orslits filled with anisotropic media has not been dealt with in previous publications. Usingthe Green function of an anisotropic medium in free space and Green identity, we derivethe equation of electric field in an anisotropic medium for TM polarized wave. Then weobtain the integral equation of electric field in an anisotropic medium. The boundary-2- 各向异性介质电磁散射及参数反演研究integral equation for a two-dimensional homogeneous anisotropic medium for TMpolarized wave are deduced. Using the duality principle we can obtain the boundaryequation when TE polarized wave is incident. After that we turn the integral equations intomatrix forms, and give the method for calculating the self-patch elements. The computedresult is also presented. Using BIM and GNM, scattering and transmission properties ofcavities and slits, such as a rectangle, trapezoid, parallelism and S shape are computed. Theinfluence of the silts' shape to scattering and transmission is discussed. The influence ofpermittivity and permeability is also discussed. Using the FDTD method the scattering of two-dimensional and three-dimensionalanisotropic object is analyzed. We deduce the FDTD formulation of two-dimensiontransverse anisotropic medium. The three-dimension FDTD formulation of anisotropicmedium with arbitrary permittivity and permeability is deduced. Equivalent parametermethod of the interface of media is presented, which is memory saving and efficient. Thescattering of two-dimensional and three-dimensional anisotropic media is computed. Mainefforts are put on the computation of scattering by an anisotropic plate, an anisotropic platebacked with a metallic or lossless isotropic plate. The relation of the scattering field wit...