A method to decrease computation time of FDTD calculations for low frequency excitations

In this paper, we propose a new way to decrease computation time of the finite difference time domain (FDTD) method. We focus on signals presenting a very large damping time such as bi-exponential waveforms. The procedure consists first in calculating the transfer function of the system from its quasi-impulse response. Next, based on this transfer function, the response to any excitation (particularly low frequency ones) is calculated. The quasi-impulse response can also be extrapolated using the matrix pencil method in order to obtain a waveform totally damped. In any case, very good agreements with FDTD complete simulations are found.