On the Solution of Electromagnetic Scattering Problems Involving Large Bodies Using the Characteristic Basis Function Method and Extrapolation Techniques

In questo lavoro vengono presentati due diversi approcci miranti a ridurre il tempo computazionale nelle analisi di problemi di scattering elettromagnetico tramite il Metodo dei Momenti. Il primo è il Characteristic Basis Function Method (CBFM) che utilizza speciali funzioni base definite su macro-domini; il secondo, invece, utilizza una tecnica di estrapolazione e permette, sfruttando la conoscenza della soluzione a basse frequenze, di determinare una soluzione a più alte frequenze, alle quali la dimensione dell'oggetto è comparabile o maggiore della lunghezza d’onda. In this disertation, two approaches are presented for reducing the computational time of Method of Moments (MoM) analysis of electromagnetic scattering problems. First, a novel method, called the Characteristic Basis Function Method (CBFM) for efficient analysis of electrically large scatterers is proposed to reduce the matrix solution time. The CBFM utilizes special types of high-level basis functions, indicated as CBFs, defined over domains that encompass a relatively large number of conventional sub-domain bases. Additionally, a new method is proposed for high frequency analysis in scattering problems. It is based on an extrapolation technique, which allows us to project the solution to higher frequencies, where the body size is large in terms of the wavelength, starting from the knowledge of the solution at lower frequencies. To date, the method has successfully tested on a two-dimensional canonical geometry for which the analytical solution is available; an extension to arbitrary geometries is planned in the future