Browsing by Author "Benson, Peter-Luke"
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- ItemTunable lumped element notch filter for UHF communications systems(Stellenbosch : Stellenbosch University, 2018-03) Benson, Peter-Luke; Meyer, Petrie; Stellenbosch University. Faculty of Engineering. Dept. of Electrical and Electronic Engineering.ENGLISH ABSTRACT: The focus of this work is to solve for the electromagnetic problem of large linear antenna arrays efficiently and accurately within the context of two-dimensional (2D), transverse magnetic (TM) Method of Moments (MoM). Provided that the meshing size is small enough, the MoM can provide accurate results for electromagnetic simulations. However, the memory storage and computational time scale as O(N2) and O(N3) respectively, where N is the number of basis functions. The electrical size solvable with given computational resources is therefore limited. To analyze large antenna arrays, the Characteristic Basis Function Method (CBFM) is employed. This technique decomposes the entire geometry into subdomains, over which, physics-based macro basis functions called CBFs are defined. By using macro basis functions, the aim is to define the same electromagnetic problem using fewer degrees of freedom as compared to the standard MoM. Firstly, a CBFM code where a subdomain is defined to be an antenna element is implemented. The results of CBFM using up to quaternary CBFs (higher-order CBFs) are compared to that of the MoM. Secondly, CBFM with larger overlapping subdomains which span multiple antenna elements in an array is defined, so as the mutual coupling in dense antenna arrays is better represented. To generate higher-order CBFs, the distance-based criterion is proposed which is found to be a more efficient procedure than the conventional tree-based approach, for larger subdomain CBFM. The results for larger subdomain CBFM including the distancebased criterion are compared to the conventional single antenna subdomain CBFM over a range of frequencies.