2ND-ORDER ABSORBING BOUNDARY-CONDITIONS FOR TLM ANALYSIS OF OPEN REGION SCATTERING PROBLEMS

A set of second-order absorbing boundary conditions is derived for the three-dimensional finite-difference TLM analysis of open region scatt ering problems. These boundary conditions are implemented into a compu ter code using a two-level discretization scheme. A simulation experim ent using a 4-term Blackman-Harris pulse excitation with very low side lobes is used to examine the efficiency of the boundary conditions. It is observed that the absorbing boundaries are perfectly transparent t o waves impinging upon them at angles between 0 and 45 degrees, and th e normal incidence reflection coefficient is less than -35 dB.