A circular-shaped perfectly matched layer strategy for rectangular FDTD grids

A circular-shaped perfectly matched layer (PML) strategy is proposed to improve the computational efficiency of finite-difference time-domain method. The boundary is built up in Cartesian coordinate system, and is designed to circular-shaped rather than rectangle-shaped in conventional strategy, which ignored the computation of four corner regions for the 2-dimensional. It is found that over a quarter of the memory can be saved. A thin layer of perfect electric conductor is set outside the PML in order to reduce the reflect wave back to vacuum domain. The numerical simulations of point source radiation problems have been accomplished to verify the proposed algorithm.