Comparison and evaluation of boundary conditions for the absorption of guided waves in an FDTD simulation

Several absorbing boundary conditions suitable for terminating the finite-difference-time-domain (FDTD) simulation of microstrip structures are compared via numerical experiments. Both a superabsorbing boundary and a modified form of Litva's dispersive boundary condition are found to produce significantly lower reflection than the traditional first-order Mur boundary. The sensitivity of these boundary conditions to the choice of the input parameters, particularly the effective dielectric constant epsilon /sub eff/, is investigated, and optimal choices of these parameters are given.<>