Near-field iterative physical optics based on distinct wave propagation vector

Abstract

The iterative physical optics (IPO) method initially developed for computing electromagnetic (EM) scattering of electrically large cavities, iteratively refines the physical optics (PO) currents to incorporate multiple reflections and diffractions within high frequency asymptotic assumptions [1]. The major advantage of IPO over the shooting and bouncing ray (SBR) method [2] is that no ray tracing is required, hence the spurious diffraction effects from non-physical shadow boundaries can be avoided [3]. The original IPO deals with far-field scattering problems. To the knowledge of the authors, no IPO method specifically suitable for near-field EM scattering has been developed. One possible approach to obtain near-field scattering with IPO, as typically done in MoM, is to resort to cumbersome expressions for the fields close to a radiating source that have been derived in [4], once the surface equivalent electric currents have been iteratively obtained. However, this approach turns out to be problematic in two aspects. First, the incident plane wave assumption is typically made, which is normally not the case, especially when the surface curvature of the object is not smooth with respect to wavelength. Second, the proper evaluation of potential integrals arised in near-field scattering calculation is very demanding.