Fast finite difference time domain method for the analysis of planar microstrip circuits

Although the FD-TD method has been successfully applied to the analysis of planar microstrip circuits eg(1), it is necessary to make improvements so that the time of analysis can be reduced. One such improvement consists in using an irregular grid (2). The aim of this paper is to show that, although the majority of published applications of FD-TD make use of a uniform grid and some authors have rejected non-uniform grids as being inaccurate (3), they are on the contrary well suited to the analysis of complex structures such as filters, and that, together with open boundary conditions and broadband excitation, they contribute considerably in reducing the computing time.