International Journal of Engineering and Technology

Thispaper introduce the comparison method in Finite Different Time-Domain (FDTD) for solving oblique incident plane wave at periodic structures. The method referred to as split-field transformation and constant transverse wavenumber (CTW) direct field transformation. In order to overcome the oblique incident where has the delay time in the transverse plane wave., the CTW tended to apply as the suitable method with the constant wavenumber in the transverse plane (x-direction) and by applying periodic boundary condition (PBC) can be directly implement in the time domain. The stability is same as conventional stability of FDTD where the time step not necessary to obtain stable result as the incident angle is increased. A set auxiliary variable (P and Q fields) is introduced for split-field to realize the discretization of transformed Maxwell’s equation is difficult to derived equation for oblique incident because the formulation required extra memory during simulation. Split-field exhibit instability for the grazing incident affect from the stability criterion. The formulations for both methods are compared to authoritative solutions.