3D macromodels in the FDTD filter analysis

This paper shows an application of 3D macromodels to filter analysis by means of the FDTD method macromodels are created using 3D FDFD description of the volume where singularities occur during a filter analysis. State equations are then used to form a second order system, which is reduced using ENOR algorithm. Reduced system (a macromodel) captures the singularity frequency behavior using a limited number of variables and is incorporated into the finite difference time domain routine as an iterative leap-frog scheme. Unlike subgridding this approach gives a high spatial resolution at a cost slightly shorter time step. Moreover, it allows one to analyze filters having strong field singularities accurately at the numerical cost comparable to that of the standard FDTD scheme.