Problem-independent enhancement of PML ABC for the FDTD method

A problem independent approach to the improvement of perfectly matched layers (PML) for the classical Yee´s finite-difference time-domain (FDTD) method is proposed. First, the spatially polynomial PML variables are allowed to vary at different exponent rates. Second, lossy termination walls are used. It is shown that each of the approaches or their combination enhances the performance of the PML in the termination of open/radiation problems as well as in the termination of high-frequency structure ports. The proposed modification in the PML variable profiles adds a new degree of freedom in their definition and leads to lower numerical reflections in comparison with the commonly used profiles for Yee´s FDTD method.