Performance optimization of the PML absorber in lossy media via closed-form expressions of the reflection coefficient

A robust closed-form expression of the reflection coefficient concerning the discrete uniaxial finite-difference time-domain/perfectly matched layer (FDTD/PML) for the termination of lossy materials is presented in this paper. The novel formulation introduces an advanced procedure in the optimized derivation of layer conductivities involving medium parameters, spatial or temporal increments, and excitation frequencies. Numerical results indicate that the proposed technique greatly diminishes artificial reflections and therefore achieves a significant accuracy.