Research On The Electromagnetic Characteristics Of Circularly Polarized Waves Based On Compatible Sub-domain Level DGTD

The Discontinuous Galerkin Time Domain(DGTD)method,as a new algorithm in the field of computational electromagnetics in recent years,has received wide attention due to its advantages of high accuracy and ease of parallelism.Since the cell-level DGTD algorithm requires the same profile type and high-precision profile size for the whole computational region to discretize the target region,this will cause excessive computational resources and time cost wastage.Therefore,reducing resource consumption and improving computational efficiency are of great value and significance in the research of DGTD methods.In this thesis,for the problem of high difficulty in solving multi-scale complex electromagnetic models,we adopt the idea of area decomposition to divide multiple sub-domains,and choose different grid dissection methods according to the fineness,while using mixed-order basis functions can well reduce resource consumption and improve computational efficiency.The method adopts two forms of Maxwell’s equations,EB and EH,as the controlling equations,and uses two types of meshes,tetrahedral and hexahedral,for dissection.The multi-domain linear discrete system equations of both forms are constructed by combining the region decomposition method,and the DGTD method is combined with the proper PML(Well-posed PML)to simulate the unbounded problem.And the vector form of Maxwell’s system of equations in the PML region and the corresponding explicit fourth-order Longacurta time iteration method are given.Meanwhile,the method can adopt different discretization strategies for PML and physical domains,and also can improve the computational efficiency of the algorithm by optimally adjusting the dissection type,dissection size,and order of basis functions of each subdomain to effectively reduce the degrees of freedom.The algorithm is applied to the solution of multi-scale electromagn etic problems,and it is found that the efficiency of the simulation can be improved by using the hybrid grid and the hybrid order basis functions.The simulation results show that the subdomain-level EB-DGTD reduces the memory consumption by 87%,the degrees of freedom by 96%,and the time cost by 99.7%compared with the celllevel DGTD method for the same magnitude of computational accuracy.Applying the EB-DGTD method to the electromagnetic scattering problem,a new circularly polarized wave injection method is proposed from the fundamental theory of circularly polarized waves,combined with the total field scattering field separation technique(TF/SF),which perfectly injects circularly polarized plane waves into the computational domain and further extends the single-frequency circular polarization to bandwidth circularly polarized waves.Through simulation,it is found that the numerical results are in good agreement with the analytical solution and also conform to the superposition principle of plane waves,which verifies the correctness of the algorithm.The circularly polarized wave injection problem of the DGTD algorithm is effectively solved.It provides a theoretical reference for the study of circularly polarized waves in the RCS simulation of computational targets.