Thesis (MscEng (Electrical and Electronic Engineering))--University of Stellenbosch, 2011. / ENGLISH ABSTRACT: The aim of this thesis is to investigate the suitability of TEM (Transverse Electromagnetic) horn antennas for use as feed structures for the Square Kilometre Array (SKA) radio telescope, in particular with regard to the roundness of the radiation pattern. A literature study shows that existing TEM horn designs do not yield a round radiation pattern over a wide bandwidth and that an alternative is required. The Method of Moments (MoM) is a computational electromagnetic (CEM) technique typically used in the analysis of TEM horn antennas. An in-house MoM solver is successfully developed to analyse such antennas and is able to calculate the current density on the surface of a conductor, as well as the farfield patterns of an antenna. A modification to an exponential TEM horn antenna is proposed and simulations show the modification is successful in yielding a round radiation pattern over a wide bandwidth. The modified exponential TEM horn has a convex triangular arc at the end of each antenna plate and is constructed for measurement. Due to limited construction capabilities, the measurements deviate slightly from the simulated results but still indicate the potential of the structure to yield a round radiation pattern over a wide bandwidth. / AFRIKAANSE OPSOMMING: Die doel van hierdie tesis is om die geskiktheid van transverse elektromagnetiese (TEM) horing antennas te ondersoek vir die gebruik as voerstrukture vir die Square Kilometre Array (SKA)- radioteleskoop, veral met betrekking tot die rondheid van die stralingspatroon. ’n Literatuurstudie toon dat bestaande TEM horing ontwerpe nie ’n ronde stralingspatroon oor ’n wye bandwydte lewer nie, en dat ’n alternatief nodig is. Die metode van momente is ’n rekenbare elektromagnetiese tegniek wat tipies gebruik word in die ontleding van TEM horing antennas. ’n In-huis metode van momente ontleder is suksesvol ontwikkel om sulke antennas te analiseer en is in staat om die stroomdigtheid op die oppervlak van ’n geleier, sowel as die vêrveld patrone van die antenna te bereken. ’n Wysiging van ’n eksponensiële TEM horing antenna word voorgestel en simulasies toon dat die veranderings suksesvol is om ’n ronde stralingspatroon oor ’n wye bandwydte te skep. Die verander eksponensiële TEM horing het ’n konvekse driehoekige boog aan die einde van elke antenna plaat en is gebou vir meting. Weens beperkte konstruksie vermoëns, toon die metings ’n afwyking van die gesimuleerde resultate, maar dui nogsteeds die potensiaal aan van die struktuur om ’n ronde stralingspatroon te lewer oor ’n wye bandwydte.

В данной работе представлена разработка схемы управления зеркальными антеннами 600 метрового радиотелескопа на основе цифровой обработки сигналов. Был произведен анализ диаграммы направленности радиотелескопа при цифровом методе формирования, а также оценено влияние фазовых ошибок на диаграмму направленности радиотелескопа, возникающих в процессе оцифровке аналогового сигнала на несущей частоте. Было произведено математическое моделирование и оценка влияния параметров цифровой элементной базы на характеристики диаграммы направленности радиотелескопа, предложено оборудование для построения диаграммообразующей схемы радиотелескопа. / This work contains the development of a control scheme for mirror antennas of a 600-meter radio telescope based on digital signal processing. An analysis was made of the radiation pattern of the radio telescope under the digital method of formation. The influence of phase errors on the radiation pattern of the radio telescope, which arise in the process of digitizing an analog signal at a carrier frequency, was estimated. Mathematical modeling and estimation of the effect of the parameters of the digital element base on the characteristics of the radiation pattern of the radio telescope were made, equipment for constructing a radio telescope was proposed.