Using discrete fourier transformation to obtain the complex amplitude of time-harmonic field in FDTD

To increase accuracy of the finite-difference time-domain (FDTD) algorithm, the discrete Fourier transformation (DFT) method is discussed in this article. The complex amplitude of time-harmonic field has been obtained by using the DFT. For the electromagnetic scattering problems, the computational error can be reduced, and efficiency is more than that of the phase delay method. Moreover, we also validated the errors for the proposed method under different absorbing boundary, such as the second-order Mur´s, uniaxial perfectly matched layer (UPML), and convolution perfectly matched layer (CPML).