Investigation of the on-surface boundary operators for electromagnetic scattering by conducting object.

摘要

This research investigation presents an approach to obtain simple analytical solution for the electromagnetic scattering and interaction by the perfectly conducting two and three dimensional arbitrary shaped objects. This has been attempted by examining the basic physics of wave propagation, and scattering in the complex near field region and the near-field radiation boundary conditions. The dissertation addresses various unresolved issues and take up a study of near-field boundary operators to demonstrate the question of accounting the relevant physics of electromagnetic scattering and interaction. The evaluation of the near-field higher order radiation boundary operators is initially studied using a canonical geometry in a two dimensional case to predict behavior of the fields in the illuminated region and low level field distributions and the critical creeping wave field effects in the shadow region. Approaches are formulated to include the nonuniform edge currents at the corners based on the electromagnetic equivalences so that arbitrary cross sectional convex geometries consisting of arbitrary edges and corners can be analyzed. Number of two dimensional canonical conducting scattering objects, such as, a circular scatterer, a triangular scatterer and a thin strip scatterer are analyzed for plane wave excitation to demonstrate applicability of the On-Surface Radiation Condition theory which is developed in this dissertation. Further implementation of the OSRC theory for the study of scattering by a three dimensional conducting object, is also considered. In the initial study, the scalar type three dimensional boundary operators are utilized to construct the three dimensional vector fields associated with a conducting sphere. Further, the various orders of three dimensional scalar boundary operators are evaluated in detail. To show applicability and limitation of the OSRC theory for the case of three dimensional scatterer, the perfectly conducting sphere is investigated using higher order radiation boundary operators using spherical wave functions. Results of the induced surface electric current and the radar cross section are reported for the case of perfectly conducting sphere in free space medium.