A Symmetric FDTD Subgridding Method With Guaranteed Stability and Arbitrary Grid Ratio

A finite-difference time-domain (FDTD) subgridding method is proposed to efficiently and accurately solve 3-D electromagnetic problems. Based on the reciprocal and symmetric interpolation operators between coarse and subgridding meshes, spatial coupling matrices are carefully designed to guarantee long-time stability. To further enhance its capability of handling multiscale structures, arbitrary grid ratios and nested subgridding meshes are extended to be supported in the proposed method. In addition, the rigorous analysis shows that the proposed FDTD subgridding method is theoretically stable. Five numerical examples including a simple cavity with perfect electric conductors (PECs), a rectangular TEM waveguide, a dielectric resonator (DR), a single-layer substrate integrated waveguide (SIW), and a large airplane platform with a dipole are carried out to validate its effectiveness. Results show that it is stable, accurate, efficient, and easy to model complex structures.