This thesis consists of three parts. The first part is an introduction and referencessome recent work on 2D electromagnetic scattering problems at high frequencies. It alsopresents the basic integral equation types for impenetrable objects. A brief discussionof the standard elements of the method of moments is followed by summaries of thepapers.Paper I presents an accurate implementation of the method of moments for a perfectlyconducting cylinder. A scaling for the rapid variation of the solution improves accuracy.At high frequencies, the method of moments leads to a large dense system of equations.Sparsity in this system is obtained by modifying the integration path in the integralequation. The modified path reduces the accuracy in the deep shadow.In paper II, a hybrid method is used to handle the standing waves that are prominentin the shadow for the TE case. The shadow region is treated separately, in a hybridscheme based on a priori knowledge about the solution. An accurate method to combinesolutions in this hybrid scheme is presented.

CAD objects are geometrical descriptions of physical scenes from the real world. Ray tracing is used to project the objects onto a pixel screen. A lit and a shadow zone are formed according to the direction of the incoming field (light) and the orientation of the pixel screen. The arc length along the surface of the object, from the shadow boundary to a point in the lit zone, is computed by means of numerical integration. The arclengths corresponding to two orthogonal directions that are aligned with the pixels on the pixel screen are computed and used for interpolation to obtain the arc length for all directions. A number of simulations for various CAD geometries are made using a ray-tracer implemented in FORTRAN 90.