In order to reduce memory usage and improve efficiency, the unconditionally stable locally 1-D (LOD)-FDTD method for bodies of revolution (BOR) is extended to Debye dispersive media based on the bilinear Z transform (BZT) theory. The LOD-BOR-FDTD method is proposed. To validate the Higher efficiency and Lower memory usage of the proposed algorithm, two numerical examples are given. Compared with the 3-D FDTD and ADI-BOR-FDTD result, they show good agreement and at least 80% of computational time to the ADI counterparts. Nakano, 2006), the numerical results is comparable to the ADI counterparts which has second-order accurate in time. Although the locally 1-D (LOD)-BOR-FDTD is developed, but no dispersive media was considered. On the other hand, the use of Z transforms (D. M. Sullivan, 1992) to the treatment of dispersive media in FDTD is an attractive alternative, since it has the advantage that the complicated convolution integrals can simply be reduced to algebraic equations, and the relationship between the flux density and the electric field can readily be translated into finite-difference equations. But we found the conventional Z transforms could bring higher error for Dispersive Media. So the bilinear Z transforms (BZT) is used to avoid error for the trapezoidal integration is more accurate than rectangular integration (D. M. Sullivan, 2000). This fact motivates us to apply the bilinear Z transforms to the LOD-BOR-FDTD for a concise frequency-dependent formulation. In this letter, we use the BZT method to build an extension of the LOD-BOR-FDTD to Debye dispersive media in order to reduce memory usage and improve efficiency.
Formulation Bilinear Z TransformsFor Debye dispersive medium having p poles, the electric flux density D and the electric field E in the frequency domain are related as (A. Taflove and S. C. Hagness, 2005)