Improvement of shadowing with Iterative Physical Optics for radiation pattern of mounted antennas

Modeling interactions between antennas and structures is an important challenge for systems carrying antennas such as aircrafts, satellites, frigates. This paper focuses on the electromagnetic field propagated by an antenna interacting with a structure that includes effects of shadowing and multiple reflections. In such a case, several method can be used, and Iterative Physical Optics (IPO) is an asymptotic method based on Physical Optics (PO), which has shown good results in calculation of electromagnetic diffraction in open-ended cavities. In IPO, different techniques can be used to take into account shadowing effects. First method, classically used, is a geometrical way of considering shadowing, based on ray bouncing. A more recent method uses a physical approach, based on shadow radiation (around forward direction) with PO approximation. The idea of this paper is to use IPO method to determine electromagnetic field from a structure including an antenna on a large complex platform, comparing different ways of considering shadowing effect.