| Deterministic expressions based on Uniform Theory of Diffraction (UTD) are widely used in ray-tracing simulation tools for the diffraction problem. Although these theories predict the fields accurately in the far-field region for simple problems, it is difficult if not impossible to extend the analysis to find diffraction coefficients for wedges composed of dielectric and imperfectly conducting materials. In fact, the classical problem of diffraction from an infinite lossless dielectric wedge has not been solved analytically.; In the past, I demonstrated the successful application of the Finite Difference in Time Domain (FDTD) method to numerically obtain diffraction coefficients for an infinite Perfectly Electrically Conducting (PEC) wedge. In this dissertation, I use the FDTD method in a similar approach in order to find the electromagnetic field in the shadowing region of the homogeneous/inhomogeneous wedge. I further extend the FDTD approach to analyze parameter sensitivity for the diffracted fields from 2-D homogeneous/inhomogeneous material wedges representing practical cases, such as corners of buildings.; This dissertation focuses on two important problems. The first investigation addresses the limitations of the UTD theory to accurately compute the diffraction coefficients for wedges composed of dielectric material (rather than PEC material only). The second investigation, which is the main focus of this dissertation, is to identify the sensitivity of the diffracted field in relation to major scattering parameters. Such parameters are the angle of wave incidence, wedge material properties (permittivity), and inhomogeneous type of wedge (metallic re-bar inside the dielectric wedge). The results from such efforts will help to develop power coefficients in the shadow region of 90 degree homogeneous/inhomogeneous wedges (building corners), in order to improve the accuracy of current and future ray-tracing tools.; The results from the parameter estimation analysis demonstrated that the TM (Transverse Magnetic) case is the preferred excitation over its counterpart, the TE (Transverse Electric) excitation. |
