The Application Of The Characteristic Basis Function Method In Electromagnetic Scattering From The Rough Surface

As one of the most popular numerical methods,the method of moments(MoM)is widely used to simulate the electromagnetic(EM)scattering from the rough surfaces for its high accuracy.Besides,in the MoM,the additional boundary conditions are not needed.However,the matrix equation of MoM is a full matrix,which requires too much computer memory and costs long time to deal with the EM scattering from the rough surface with many unknowns.In this thesis,the Characteristic Basis Function Method(CBFM)is used to study the EM scattering from a one-dimensional(1-D)rough surface and the composite scattering from the rough surface with the target.Then,by introducing a current criterion,the adaptively modified characteristic basis function method(AMCBFM)is applied to simulate the EM scattering from the 1-D Perfectly Electric Conductor(PEC)rough surface,in which the order of characteristic basis functions can be adaptively halted.Finally,the AMCBFM is combined with the Maehly technology(AMCBFM-Maehly)to fast and accurately simulate the EM scattering from the 1-D rough surface over a frequency band.Main works of this thesis are as following:1.The basic principle of MoM is given.The integral equation and the matrix equation of simulating the EM scattering from 1-D PEC rough surface by the MoM are exhibited in detail.And the MoM is applied to simulate the EM scattering from dielectric rough surface and the composite scattering with a cylinder located above it.Moreover,the influences of the root mean square height,the correlation length of the rough surface and the radius,the position of the cylinder on the EM scattering are discussed.2.The fundamental of the CBFM and the application of CBFM in EM scattering from a one-dimensional PEC rough surface is shown.Moreover,the CBFM is applied to simulate the EM scattering from a dielectric rough surface.The influences of the number of subdomains and the order of the secondary characteristic basis function on the results are discussed.3.The basic principle of AMCBFM is introduced.And the AMCBFM is used to calculate the EM scattering from the 1-D PEC rough surface.Finally,the CPU time and the results of the AMCBFM are compared with the MoM,The accuracies and the effectiveness of the AMCBFM are illustrated.4.The AMCBFM is combined with the Maehly technique(AMCBFM-Maehly)to simulate the EM scattering from the 1-D rough surface over a frequency band,and the results are compared with the MoM.