Authors: Giacomo Bianconi and Raj Mittra
Source: FERMAT, Volume 2, Article 4, Mar.-Apr., 2014
Abstract: In this paper we present an efficient numerical technique, called the Characteristic Basis Function Method (CBFM), for the electromagnetic analysis of planar microstrip structures as well as for a class of three-dimensional scattering problems. In this method, the original problem geometry is segmented into smaller regions called blocks, and high-level basis functions are generated to represent the electromagnetic characteristics of these sections. These basis functions are referred to as the Characteristic Basis Functions (CBFs), and their use leads to a reduced matrix equation system. Since the method only requires the solution of relatively small-size matrix equation, both in the process of generating the CBFs and in the solution of the reduced matrix, the overall computational burden is reduced in terms of the memory requirement relative to the conventional Method of Moments (MoM) approach, and an acceleration of the solve time is also achieved. The Characteristic Basis Function Method is next combined with the Equivalent Medium Approach (EMA) for fast and efficient design of microstrip circuits etched on layered media. In particular, the developed EMA method substitutes the stratified environment with an equivalent “homogeneous” medium whose Dyadic Green's Functions (DGF's) can be evaluated analytically. The above technique yields reliable results and reduces the computational time in comparison with the conventional Method of Moments. In the second part of the paper, the CBFM will be applied to the solution of electromagnetic scattering problems involving plasmonic nano-rod array antennas operating in the Terahertz regime. In particular, the formulation necessary for the analysis of a single nano-rod is introduced and subsequently generalized to the case of a double-periodic array and to the case of a finite randomly tilted array. Several numerical examples which demonstrate the accuracy and the efficiency of the described procedures are included, both for the case of microstrip structures as well as for the nano-rod antennas.
Index Terms: Method of Moments (MoM), Characteristic Basis Function Method (CBFM), Dyadic Green's Function (DGF's).
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Efficient Analysis of Microwave Circuits/Printed Antennas and Scattering Problems via the Characteristic Basis Function Method (CBFM)