THEORETICAL AND NUMERICAL STUDY OF CONICAL DIFFRACTION BY CYLINDRICALOBJECTS

Thanks to a Fourier transform with respect to the spatial coordinate d escribing the direction of the cylinder axis, we are led to a two-dime nsional problem. A set of four integral equations is then established from a rigorous integral theory, where the Fourier transform of the fi eld on the surface of the cylinder is unknown. With the help of a boun dary finite elements method, the integral system is converted into a l inear system of equations. This system is not uniquely solvable for a discrete set of irregular frequencies. However, it is possible to over come this difficulty by adding constraints out of the boundary. To ens ure the accuracy of the numerical implementation, the singular parts o f the kernels are isolated and their integration is performed analytic ally. In this paper, results are given when the excitation is a plane wave with arbitrary polarization and oblique incidence (conical diffra ction), but only the knowledge of the Fourier transform of the inciden t field is required.