Analysis of Crack Problem by using ADI-FDTD/MoMTD Hybrid Method

In general, the hybrid method of moments in time domain (MoMTD) and finite difference in time domain (FDTD) is applied for problems that an antenna, especially wire antenna, is located near a multilayer scatterer. MoMTD and relative equations model antenna as a Huygens’s surface. FDTD calculates fields in area that includes scatterer. When there is a small size - toward minimum wavelength- part in the scatterer, time step must be very small, because of the Courant condition. So the runtime of FDTD becomes long. In this paper we want to solve the time consuming problem of the hybrid MoMTD-FDTD. We used a newer kind of FDTD that called ADI-FDTD instead of FDTD. ADI-FDTD is unconditionally stable and there is no need for Courant condition anymore. As an ADI-FDTD problem, we chose to solve the problem of crack detection in a wall.