Thin‐slot formalism for the split‐field FDTD analysis of periodic structure

An expression of the thin-slot formalism is presented to alleviate the gridding of the split-field finite-difference time-domain (FDTD) solution for periodic structure. The varying auxiliary-field ( P¯, Q¯) and split-field ( P¯a, Q¯a) distributions near the slots are analytically derived from the varying field ( E¯, H¯). The update equations for the split-field FDTD are obtained by incorporating those varying field distributions into the split-field equations in integral form. A frequency selective surface (FSS) structure is applied to verify the proposed method. The results indicate that the computational efficiency is improved.