Scattering of an object above a rough surface with impedance boundaries using IPO and FMM

Scattering from an electrically large object above a random Gaussian rough surface both having impedance boundaries is treated using the approximate high frequency technique, iterative physical optics (IPO) together with the efficient fast multipole method (FMM), leading to a relatively fast and efficient technique. First, a separate and brief review of the IPO and FMM approaches, and second different simulation results of an object with and without a relatively large rough surface are provided. Numerical simulations are verified through comparison with either existing or full-wave numerical results.