Masters Degrees (Electrical and Electronic Engineering)
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Browsing Masters Degrees (Electrical and Electronic Engineering) by Author "Alphonse, Stephanie"
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- ItemFast analysis of a compound large reflector antenna(Stellenbosch : Stellenbosch University, 2012-03) Alphonse, Stephanie; Palmer, K. D.; De Villiers, D. I. L.; Stellenbosch University. Faculty of Engineering. Dept. of Electrical and Electronic Engineering.ENGLISH ABSTRACT: The o set Gregorian dual re ector antenna is eminently well suited to a radio telescope antenna application as it o ers a narrow beam width pattern (i.e high gain) and good e ciency. The focus of this work is on the analysis of characteristics of such a Gregorian antenna. The design of the class of re ector antennas is normally based on the use of ray-optics, with this simpli ed approach being able to predict antenna performance based on approximate formulas for example the beam width against aperture size. However for compound antennas such as the Gregorian re ector there are several interdependent parameters that can be varied and this reduces the applicability of the simple ray-optic approach. It was decided that, if a fast enough analysis of a con guration can be found, the technique of design through interactive analysis would be viable. To implement a fast analysis of the main beam performance of such a Gregorian antenna, a solution algorithm has been implemented using a plane wave spectrum approach combined with a custom aperture integration formulation. As this is able to predict the beam performance within about a second on a PC, it is suitable for iterative design. To implement the iterative design in a practical manner a user interface has been generated that allows the user to interactively modify the geometry, see the physical layout, and then nd the antenna pattern. A complete working system has been realised with results comparing well to a reference solution. The limitations of the technique, such as its inaccuracy in predicting the side lobe structure, are also discussed.