Combined structural and electromagnetic analysis of dish reflection antennas

Thesis (MEng)--Stellenbosch University, 2018.ENGLISH ABSTRACT: In recent scientific endeavours, such as the Square Kilometre Array (SKA) project, significant attention (and funding) is being allocated to the design and analysis of radio telescope antenna systems, especially dish reflectors. For radio astronomy the accuracy requirements are very strict, and small changes in the shape of these antennae could result in these specifications no longer being met. In this study, a workflow process was developed to aid in the analysis of the radio telescopes while they are subject to gravitational deformation. The workflow describes procedures for performing coupled structural and electromagnetic analyses, as well as the procedures for sharing the simulation models between the respective solvers. Finite element analysis was used for the structural analysis and the method of moments and multilevel fast multipole method were used for the electromagnetic analysis. Simulations were run using the workflow process and the results compared to approximate analytical equations, where a good correlation was found. A numerical optimisation study was conducted on a simple primary-fed reflector antenna model to demonstrate how the workflow could be used in such an analysis. A case study of a real-life Cassegrain antenna was performed, and the results of these simulations were found to be similar to those of a previous study.AFRIKAANSE OPSOMMING: In onlangse wetenskaplike pogings, soos die Square Kilometer Array (SKA) -projek, word aansienlike aandag (en befondsing) toegewys aan die ontwerp en analise van radioteleskoop-antennestelsels, veral reflektore. Vir radio-astronomie is die akkuraatheidsvereistes baie streng. Klein veranderinge in die vorm van hierdie antennas se gevolg kan wes dat hierdie spesifikasies nie meer nagekom word. In hierdie studie was ’n werkvloeiproses ontwikkel om te help met die analise van die radioteleskope, terwyl hulle onderworpe is aan gravitasie vervorming. Die werkstroom beskryf prosedures vir die uitvoer van gekoppelde strukturele en elektromagnetiese ontledings, asook die prosedures vir die deel van die simulasiemodelle tussen die onderskeie oplossers. Eindige element analise was gebruik vir die strukturele analise, en die metode van momente en multilevel vinnige multipol metode was gebruik vir die elektromagnetiese analise. Simulasies was uitgevoer deur die werkvloeiproses. Die resultate vergelyk met benaderde analitiese vergelykings, waar ’n goeie korrelasie gevind was. ’N numeriese optimaliseringsstudie was uitgevoer op ’n eenvoudige primêregevoed-reflektor antenna model om te demonstreer hoe die werkstroom gebruik kan word in so n analise. ’N Gevallestudie van ’n werklike Cassegrain-antenna was uitgevoer, en die resultate van hierdie simulasies was gelykstaande aan dié van ’n vorige studie