A Technique for Efficiently Modeling Long-Path Propagation for Use in Both FDFD and FDTD

A technique is developed for the efficient modeling of propagation over long paths (hundreds of lambda) by breaking the path up into segments and appropriately applying the perfectly matched layer (PML) absorbing boundary condition and the total field/scattered field boundary condition. For finite-difference time-domain (FDTD) simulations the new technique is well suited to model both slow- and fast-wave modes as well as scattering inhomogeneities along the path. In addition, the new technique is directly applicable to finite-difference frequency-domain (FDFD) simulations. Both FDTD and FDFD numerical simulations of propagation within the Earth-ionosphere waveguide are performed to validate the new technique