A Hybrid Algorithm of 3-D Explicit Unconditionally Stable FDTD and Traditional FDTD Methods

The explicit unconditionally stable finite-difference time-domain (EUS-FDTD) algorithm has the characteristics of explicit iteration and unconditional stability. It exhibits high efficiency in addressing electromagnetic issues with fine structures. However, it is necessary to solve partial eigenvalues and eigenvectors of the system matrix, which is inefficient when there are many unknown variables. This letter proposes a hybrid algorithm of EUS-FDTD and traditional FDTD (T-FDTD) for the three-dimensional case. The EUS-FDTD method is employed to solve the electromagnetic fields near the fine structure, and the T-FDTD algorithm is used in the remaining areas. Field value correction and exchange are performed at the regional boundaries of the two algorithms, which greatly reduces the scale of the eigenvalue solution and improves calculation efficiency. Numerical experiments demonstrate the effectiveness of the proposed method.