Aperture Efficiency of an Array Fed Truncated Cassegrain Reflector Antenna
Typ
Examensarbete för masterexamen
Master's Thesis
Master's Thesis
Program
Wireless, photonics and space engineering (MPWPS), MSc
Publicerad
Författare
Henkow, Victor
Modellbyggare
Tidskriftstitel
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Volymtitel
Utgivare
Sammanfattning
Abstract
If a reflector antenna needs to be mechanically steered, it can sometimes be necessary to truncate the sides of the main reflector to keep it from hitting the structure behind it. If the feed is kept circularly symmetric when the main reflector is truncated, it will lead to a low aperture efficiency. In this report a truncated Cassegrain reflector antenna was studied. The purpose was to investigate
if the aperture efficiency could be improved by feeding the antenna with a two element horn array instead of a single horn. This was done by doing simulations in CST Studio Suite and optimizing using a Python script. Both types of feeds were modeled with the same limitations, so that the single horn antenna could act as a control. To improve the simulation time, the whole antenna was not optimized, instead the aperture efficiency was calculated from the feed using the spillover efficiency, the polarization efficiency, the illumination efficiency and the phase efficiency. The best single horn feed design had an aperture efficiency of 41%, and the best array feed design had an aperture efficiency of 49%. This indicates that the array feed is more efficient. However, the design that was tested was only a proof of concept, ignoring other efficiencies. The conclusion is that the concept shows potential, but more research needs be done before any conclusions about a realizable design can be made.
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Keywords: truncated reflector, Cassegrain, dual reflector, array feed, aperture efficiency, asymmetrical reflector, elliptical beam, linear array feed, elliptical sub reflector.