Radial Perfectly Matched Layer for the ADI-FDTD Method

In this letter, a circular absorbing boundary using the radial perfectly matched layer (RPML) is investigated for the alternating-direction-implicit finite-difference time-domain (ADI-FDTD) method. A staircase approach is used to approximate the circular boundary so that it is directly compatible with the commonly used Yee´s lattice. The proposed RPML boundary is computationally more efficient than the traditional rectangular PML boundary. It was found that more than 20% of the memory and computation time can be saved by using the proposed method.