A Fast Method For Eigenmode Analysis Of Electromagnetic Problems With Repetitive Structures

The repetitive structure is widely used in practical engineering,while the full-wave simulation of large repetitive structure is too costly.Therefore,it is of great theoretical and practical significance to study accurate,fast and efficient solutions.The characteristic modes(CMs)method has been widely concerned in the field of electromagnetism since it was proposed.The CMs are only associated with the inherent physical properties of target,so they are very suitable as the global basis functions of the target for expanding the current of the surface,which can reduce the unknowns.In this paper,we focus on the electromagnetic problems of repetitive structure and repetitive structure conformal to carrier platform.The main work of this paper is summarized as follows.In the first part,we analyze the repetitive structure with CMs method,and even in a broadband.Firstly,discrete repetitive structure is in analysis.Extracting characteristic modes of a single unit and reusing it.The translational invariance between units can also accelerate the solution.Then the connected repetitive structure is analyzed,including metal and medium connection.The methods of extracting characteristic modes of these two are proposed respectively,so the modes can be reused in the targets.At last,the relation between CMs and frequency is discussed,and the method of extracting frequency independent characteristic modes(FICM)is proposed,which is valid in an interest broadband.In the second part,the repetitive structure conformal to carrier platform with CMs is mainly analyzed.Firstly,the coordinate mapping method is introduced.Then the CMs method of this structure is proposed: extracting characteristic modes of a single unit of repetitive structure,while just computing carrier platform with traditional moment of methods(Mo M).When the target is oversize in electrical size,multilevel fast multipole algorithm(MLFMA)is introduced to accelerate the impedance matrix filling,reduced order and the iterative process.Finally,the parallel technology based on MPI-OPENMP is proposed to minimize the consumption of computing resources and greatly improve the computational efficiency.Examples are provided to verify the accuracy and efficiency of the proposed CMs method for the rapid analysis of repetitive structure and repetitive structure conformal to carrier platform.