Browsing by Author "Chose, Matthews"

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    Analysis of large disjoint antenna arrays by localised solutions
    (Stellenbosch : Stellenbosch University, 2023-03) Chose, Matthews; Botha, Matthys; Stellenbosch University. Faculty of Engineering. Dept. of Electrical and Electronic Engineering.
    ENGLISH ABSTRACT: The method of moments (MoM) is well suited to the full-wave electromagnetic analysis of antenna arrays. This is especially true for perfect electrically conducting (PEC) antennas, when an electric field integral equation (EFIE) formulation with Rao-Wilton-Glisson (RWG) basis functions is the typical approach. This yields fully populated matrices with the solution cost growing rapidly with array size N, as O(N3) and O(N2) for the runtime and storage respectively, when a standard direct solver is employed. This work is concerned with the efficient an d re liable EF IE RWG MoM an alysis of large antenna arrays consisting of identical disjoint PEC elements. Examples of such arrays are encountered within the international Square Kilometre Array (SKA) project, which motivates this work. The new formulations proposed are based on a MoM domain decomposition technique known as the domain Green’s function method (DGFM), which is a perturbation technique developed for analysing large disjoint antenna arrays. It was originally formulated in the context of printed substrate antennas, but has since been applied more broadly. In its existing form, the DGFM is limited to fairly sparse arrays where mutual coupling effects are less pronounced. Three DGFM-based extensions are proposed, in order for the method to be applicable to dense and very large antenna arrays. The first i s t o i ntroduce l arger l ocal solution domains in combination with an iterative scheme, to enable solutions to a pre-specified accuracy. The second is a physics-based row expansion direct-coupling technique, which is a necessary variation on the standard DGFM approach to far couplings, in order to maintain efficiency wh en de aling wi th mu ltiple si ngle-element ex citations fo r embedded element pattern calculations. Thirdly, a hybrid, single-level adaptive cross approximation (ACA) matrix compression scheme is proposed, which is tailored to the acceleration of the DGFM and is applicable to both new formulations. Results for antenna arrays relevant to the SKA low-frequency band show efficient and reliable performance.