Optimum PML ABC conductivity profile in FDFD

We address the problem of optimally choosing the conductivity (sigma) profile of a perfectly-matched-layer absorbing boundary condition (PML ABC) with prescribed number of layers so as to minimize reflections for a wide range of incidence angles and for a narrow (CW) or broad frequency-band. A new one-dimensional (1-D), frequency-domain description of 2-D PML performance is developed, validated and used in PML-sigma profile optimization. An exhaustive search for PML-sigma profiles that minimize reflections over a prescribed wide angle-range is carried out. Our procedure yields PML-sigma profiles with better performance than previously reported values, for given number of layers.