| The Luneberg lens is a type of spherically symmetric lens antenna. Due to the property of spherically symmetry, Luneberg lens antennas are widely used in satellite communications,Radar and electronic counter measures (ECM), etc. This thesis is to study a layered Luneberg lens antenna both theoretically and experimentally. The thesis mainly has the following contents:Firstly, the operating principle and the optic characteristics of Luneberg lens antennas are introduced. The vector spherical wave expansion method is adpoted to analyze the Luneberg lens by considering the lens'spherically layerd configuration. The computation results agree well with the results simulated by the commercial EM software FEKO.Secondly, two traditional design methods are discussed and their defects are pointed out. The highly efficient feed horns are used to illuminate the lens in order to achive higher radiation efficiency. The Luneberg lens is then optimized by differential evolution algorithm. The optimization results show that the Luneberg lens can achieve optimal gain with relatively fewer layers. The optimal permittivity, thickness of each layer, the focus distance between the feed and the surface of the lens are obtained by the DE algorithm. In comparison with the spherical Luneberg lens, hemispherical Luneberg lens can be used to achive the same radiation efficiency only with half of the size of an entire sphere. According to this, the optimal spherical results are suitable for the hemispherical lens. Then, the tolerance of the permittivity and the focus distance including the air layers are also investigated. Finally a traking system scheme is put forward. The research has wide applications in engineering.In general, comprehensive studies were carried out for high-performance Luneberg lens antennas, including theoretical analysis, optimization design, tolerance analysis and preliminary tracking systems. The studies have practical engineering application values. |
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