ABSORBING BOUNDARY-CONDITIONS FOR THE MODELING OF SCATTERERS IN PARALLEL-PLATE TRANSMISSION MEDIA

In modeling wave propagation using the Finite Difference Time Domain ( FDTD) method, the field gradients at each point are calculated using c entral difference approximation, For points on the edge of the model v olume a separate algorithm to simulate absorbing boundaries has to be used, Most of these absorbing boundary conditions assume normal wave i ncidence at the boundary, but at the sides of stripline or microstrip this is not the case. This letter proposes a variant of dispersive bou ndary conditions with one phase velocity given an infinite value to re present a wave travelling parallel to the boundary. When applied to un iform stripline, these boundary conditions gave better results than th e original version of the dispersive boundary condition with two finit e phase velocities, These boundary conditions enable the use of a smal ler calculation volume, thus saving computing memory and time.