Iterative physical optics algorithms for computing the EM scattering of open ended cavities

The analysis of high-frequency scattering from electrically large open cavities is addressed in this work. A formulation based on the high frequency (HF) asymptotic principles of physical optics (PO) is developed for analyzing the scattering by relatively arbitrary open-ended waveguide cavities. A magnetic field integral equation (MFIE) relating the equivalent electric currents on the interior cavity walls is obtained and solved by two different algorithms based on PO. The first method "iterative Physical Optics" (IPO) solves the equation applying iteratively PO in order to account multiple reflections inside the cavity. The second algorithm "Progressive Physical Optics" (PPO) solves the MFIE equation in a single iteration by progressive application of PO from the aperture to the termination and then using a reciprocity integral to obtain the external scattered field. Numerical results are presented which demonstrate the convergence and accuracy of the method by comparison with modal reference solutions.