The Analytical Solution Of Electromagnetic Scattering By A Buried Isotropic Medium Sphere

Based on the image method,the addition theorem of three-dimensional vector wave functions and the electromagnetic scattering characteristics by a buried sphere,an analytical method is proposed to solve the multiple scattering problem of subsurface concentric double-layer spheres.A theoretical study of the scattering characteristics of two concentric double-layered spheres: doublelayer dielectric sphere and coated conductor spheres-is mainly carried out as follows.Firstly,based on the propagation characteristics of uniform plane wave and the theoretical knowledge of the vertical incidence of uniform plane wave to the medium dividing plane,the transmitted wave of this uniform plane wave in the dividing plane is derived.The transmitted wave is incident as the incident wave of the subsurface double-layer dielectric sphere,and this incident plane wave is expanded into the analytical expression of the spherical vector wave function using the spherical vector wave function.Then,apply the boundary conditions of the tangential continuity of the electromagnetic field and the tangential orthogonality of the spherical vector wave function on the surface on the inner and outer dividing surfaces of the double-layer dielectric sphere,respectively,to find the reflected wave coefficient matrix of the double-layer dielectric sphere,and the reflected wave of the double-layer dielectric sphere will be incident vertically as the incident wave of the dividing plane,use the image method to solve for the reflected wave generated by the dividing plane on the incident wave and use the three-dimensional vector addition theorem to convert its coordinate system.On the basis of completing the study of underground double-layer media spheres,a corresponding theoretical study of the electromagnetic scattering characteristics of underground coated conductor spheres with uniform media is carried out using the boundary condition that the electric field is tangentially zero(attenuated)at the conductor sphere surface and the tangential component orthogonal property of the sphere vector wave function.The numerical results are given,and the effects of various aspects on the electromagnetic scattering characteristics,such as the media properties,dimensions and burial depth of the underground concentric double-layer spheres,are analyzed.The results of the Fortran program written based on the theory of this thesis are in good agreement with the commercial software FEKO and are much faster than FEKO.