Dielektrik rasgele dalgalı yüzeylerden elektromanyetik dalga saçılmasında iteratif yöntemlerin uygulamaları

Mobile radio planning requires accurate prediction of electromagnetic fieldstrengths over large terrain profiles. However the conventional method of mo-ments (MoM) becomes unsuitable for electrically large rough dielectric surfaces,because of the O(N 3 ) computational cost due to the large number of surfaceunknowns N . Iterative Methods are beneficial methods for faster electromag-netic problem solutions. By using such methods, very accurate results can beachieved, causing a computational cost of O(N 2 ). In this work, among the sta-tionary iterative methods; Forward-Backward Method (FBM), and among thenonstationary iterative ones; Conjugate Gradient Squared (CGS), BiConjugateGradient Stabilized (Bi-CGSTAB) and Quasi Minimal Residual (QMR) Methodsare presented to investigate the electromagnetic wave scattering from dielectricrandom rough surfaces. These techniques are compared to each other over variouskinds of surface models that reflect the real terrains to find out the best solutionmethodologies. Furthermore, efficiency of the methods are assessed by compar-ing the obtained scattering results, normalized radar cross sections (NRCS) ofthe surfaces considered, with the numerically exact ones computed by employingthe MoM.Keywords: Random Rough Surface Scattering, Method of Moments (MoM),Forward-Backward Method (FBM), Conjugate Gradient Squared Method (CGS),BiConjugate Gradient Stabilized Method (Bi-CGSTAB), Quasi Minimal ResidualMethod (QMR), Normalized Radar Cross Section (NRCS).iv