A subgridding technique for the CIP method

In this study, we propose a subgridding technique in the constrained interpolation profile (CIP) method in order to simulate electromagnetic fields in the presence of objects with fine structures. The subgridding technique consists of spatial and temporal interpolations at the interface between main coarse grids and local fine grids. In the present study, we consider a two-dimensional problem with TM_z polarization. In order to examine the validation of the proposed method, spatial and temporal interpolation schemes are implemented separately. The numerical results show that both the interpolation schemes operate successfully, and the relative errors are extremely small in wide frequency band.