Study On Scattering Characteristics Of Typical Electromagnetic Beam

In this thesis,by taking a spheroid and a circular cylinder of finite length as examples,some investigations are carried out on the scattering characteristics of typical electromagnetic(EM)beams by dielectric and chiral media.Typical Beams include the Gaussian beam,zero-order Bessel beam(ZOBB)and Hertzian electric dipole(HED)radiation.The author's main works and contributions are as follows:1.As the widely used analytical and semi-analytical solutions,the generalized Lorenz-Mie theory(GLMT)and extended boundary condition method(EBCM)are introduced in detail,which are used as a standard of accuracy in the evaluation of the present method.2.By expanding the scattered fields as well as the fields within the dielectric object in terms of the spherical vector wave functions(SVWFs)and then by applying the boundary conditions,a set of simultaneous linear algebraic equations are derived to solve for the unknown expansion coefficients by choosing appropriate weighting functions following the method of moments(MoM)procedure,therefore the expansion coefficients and the scattered fields are determined.For incidence of a Gaussian beam,ZOBB and HED radiation,by programming with MATLAB numerical results of the normalized differential scattering cross section are given to a dielectric spheroid and a dielectric circular cylinder of finite length.3.Based on the field expansions in terms of the SVWFs and the MoM scheme,an exact semi-analytical solution is presented to the scattering by a chiral object illuminated with a Gaussian beam,ZOBB and HED radiation,and the scattering properties are analyzed concisely.