Three-dimensional subgridding algorithm for FDTD

In many computational problems solved using the finite-difference time-domain (FDTD) technique, there is a need to model selected volumes with higher resolution than the whole computational space. An efficient algorithm has been developed for this purpose that provides the mesh refinement by the factor of two in each direction. The algorithm can be used in two-dimensional (2-D) and three-dimensional (3-D) problems and provides for subgridding in both space and time. Performance of the 3-D algorithm was tested in waveguides and resonators. A high accuracy and efficiency were observed in all test cases with insignificant (of an order of -60 dB) reflections from mesh interfaces. Practical applications of the algorithm in the analyses of a resonator with a dielectric rod and of a cellular phone behavior in the vicinity of the operator head are also reported.