A Research And Application Of Hybrid High Frequency Methods And Integral Equation Methods

The hybrid algorithm provides a possible way to keep their advantages while the disadvantages solved.The high-frequency method combined with the integral equation method(MoM-PO)has overcome the limitations of high-frequency and low-frequency methods.It can develop their respective advantages,especially in solving the EM problems of composite targets with complex large-scale and fine structures.Among these issues,the high-frequency method is a good way in handling large-scale objects while the integral equation method is utilized in precise structure.Hybrid high frequency and integral equation methods have good accuracy,high efficiency and affordable computer memory,etc.The work in this paper is based on the above mentioned background.Its content includes:1.The study based on trimmed Non-uniform rational B-spline(NURBS)surface is presented.Considering about the disadvantages of plane geometry model,NURBS is introduced to solve this problem.However,it is not capable of getting rid of additional surfaces in the NURBS,which is applied in EM engineering.The trimmed NURBS surface is introduced here to eliminate this problem.Compared with traditional NURBS surface,trimmed NURBUS surface gains significantly on providing more efficient answers in analyzing EM engineering.To prove this theory,several relative simulations are presented.2.An efficiently iterative hybrid algorithm is studied.Since the conventional MoM-PO method is very time-consuming.The efficient iterative MoM-PO(EI-MoM-PO)method is proposed,which is modified directly in each step of iteration.It can greatly reduce the more computational time and keep better accuracy.Besides,MLFMA is introduced in MOM's region,EI-MLFMA-PO is proposed to accelerate solution speed with smaller computer memory.Finally,based on an approximately plane structure,the hybrid algorithm provide an efficient shadowing technology with two sets of meshes.The hybrid algorithm has advantages of fast shadowing and good portability.3.IE-DDM combined with PO is studied.In the analysis of complex multi-scale problems,the integral equation domain decomposition method(IE-DDM)has great advantages.On the one hand,IE-DDM adopts different calculation methods for different sub-regions and has the advantages of natural parallel.On the other hand,IE-DDM can calculate electromagnetic engineer with non-common mesh.Based on the separated or the whole of the large-scale structure and the complex fine structure,this paper proposes two ways to combine IE-DDM method with physical optics.The method greatly enriches DDM,and efficiently improves the speed of the solution in the composite structure with the large-scale objects.Besides,it has paved the way for the subsequent addition of finite element and other solvers into DDM,and provides a possibility for further solving complex multi-scale problems.