Generalized Scattering Matrix Modeling of Distributed Microwave and Millimeter-wave Systems

KHALIL, AHMED IBRAHIM. Generalized Scattering Matrix Modeling of Distributed Microwave and Millimeter-Wave Systems. (Under the direction of Michael B. Steer.) A full-wave electromagnetic simulator is developed for the analysis of transverse multilayered shielded structures as well as waveguide-based spatial powercombining systems. The electromagnetic simulator employs the method of moments (MoM) in conjunction with the generalized scattering matrix (GSM) approach. The Kummer transformation is applied to accelerate slowly converging double series expansions of Green’s functions that occur in evaluating the impedance (or admittance) matrix elements. In this transformation the quasi-static part is extracted and evaluated to speed up the solution process resulting in a dramatic reduction of terms in a double series summation. The formulation incorporates electrical ports as an integral part of the GSM formulation so that the resulting model can be integrated with circuit analysis. The GSM-MoM method produces a scattering matrix that represents the relationship between waveguide modes and device ports. The scattering matrix can then be converted to port-based admittance or impedance matrix. This allows the modeling of a waveguide structure that can support multiple electromagnetic modes by a circuit with defined coupling between the modes. Since port-based representations are not suited for most circuit simulation tools, a circuit theory based on the local reference node concept, is developed. The theory adapts modified nodal analysis to accommodate spatially distributed circuits allowing conventional harmonic balance and transient simulators to be used. To show the flexibility of the modeling technique, results are obtained for general shielded microwave and millimeter-wave structures as well as various spatial power combining systems. Biographical Summary Ahmed Ibrahim Khalil was born in Cairo, Egypt, on November 15, 1969. He received the B.S. (with honors) and M.S. degrees from Cairo University, Giza, Egypt, both in electronics and communications engineering, in 1992 and 1996, respectively. From 1992 to 1996 he worked at Cairo University as a Research and Teaching Assistant. While working towards his Ph.D. degree in electrical engineering at North Carolina State University, since 1996, he held a Research Assistantship with the Electronics Research Laboratory in the Department of Electrical and Computer Engineering. Interests include numerical modeling of microwave and millimeter-wave passive and active circuits, MMIC design, quasi-optical power combining, and waveguide discontinuities. He is a student member of the Institute of Electrical and Electronic Engineers and the honor society Phi Kappa Phi.