2-D Hybrid Cylindrical FDTD Method With Unconditional Stability

A 2-D hybrid method combining cylindrical explicit and unconditionally stable finite-difference time-domain (CEUS-FDTD) with traditional cylindrical FDTD (C-FDTD) methods is proposed to analyze the electromagnetic cylindrical structures efficiently. The unconditional stability of the proposed method is achieved by eliminating the unstable modes which are obtained by solving the eigenvalue problem of the system matrix. However, solving global eigenvalue is time-consuming. To solve this, the domain is divided into the CEUS-FDTD region and C-FDTD region by analyzing the spectral radius of one single grid. All unstable modes can be found only in the CEUS-FDTD region. The electric fields on the boundary of the two regions are corrected without any approximation. The proposed method saves iteration time compared to C-FDTD and costs less time than CEUS-FDTD for the eigenvalue solution. Results show validity and efficiency.