Electromagnetic Scattering Analysis Of Thin Dielectric-coated Targets

Thin dielectric layer structure is widely used utilized in practical engineering projects.Not only is it used in the surface coating of aircrafts with complex construction,it is also widely used in the design of microstrip antenna and radome.In the study of the stealth techniques,reduction of radar cross section(RCS)is a generally used method to enhance the stealth performance of the radar system or the aircraft system.Utilizing absorbing material as the coating of the structure can reduce the RCS and enhance the viability of the aircraft.The full-wave modeling approach can bring huge amounts of unknowns,which tremendously increases the calculating difficulty.In order to realize the simulation and analysis of electromagnetic characteristics of thin dielectric-coated targets,relative electromagnetic approximation algorithms emerge at the moment.Current approximation algorithms to analyze thin dielectric-coated targets include impedance boundary condition and thin dielectric sheet equivalent method.Impedance boundary condition has great effectiveness limitations and wide applicability.Thin dielectric sheet equivalent method has higher demand for computing resources,since the normal component of the field is defined by pulse basis function,which can give rise to the amount of the unknowns.On the basis of the theory above,this thesis studies on the approximation method of thin dielectric-coated structures.This thesis first introduces the basic theory of method of moments(MoM),including the basic process and the widely-used RWG basis function.Then it introduces the formulation of electric field integral equation,magnetic field integral equation and combined field integral equation and shows the solution of these equations by using MoM.Aiming at the scattering problems,this thesis discusses the solving method of two different kinds of scattering field,near field and far field,respectively.On the basis of the theory above,this thesis emphasizes on the basic theory of coating,including the mainstream algorithms of impedance boundary conditions and thin dielectric sheets.It also proposes an equivalent model of generalized thin dielectric coating sheet.RCS is calculated through programming.Comparisons of the results with that of the full-wave model and equivalent model by utilizing business software are made to verify the correctness of the algorithm.Comparing with the full-wave model,the utilization of the thin dielectric coating model does not produce extra unknowns while guaranteeing the accuracy of the result,which reduces the consumption of computing resources.Therefore,the utilization of this method can be used in the solution and analysis of thin dielectric-coated targets.Later,in order to deal with problems of high calculation amount,high memory demand and non-convergent problems brought by cavity problems which MLFMA cannot solve,this thesis can realize the parallelization of matrix filling and direct solution of the matrix equation.At last,MPI(Message Processing Interface),one distributed memory programming mode,is adopted to realize the parallel algorithm of thin coating targets,which could help realize the analysis of electromagnetic characteristics of thin dielectric targets by utilizing high-performance computers to enlarge the calculation scale.