| Main task of this dissertation is designing a multi-beam lens antenna to both improve the resolution and reduce the imaging time of the passive millimeter-wave imaging system. The multi-beam lens antenna is studied systematically, including the imaging theory, multi-point focus performance, design and implementation of the feed and the simulation method of the lens antenna and so on. It can be summarized as follows.Firstly, the passive millimeter-wave imaging technologies are overviewed. And a variety of antenna technologies applied in passive millimeter-wave imaging system are also analyzed.Secondly, we analyze and simulate the multi-point focus performance of common lens, and provide the relationship between the geometric parameters and the multi-point focus performance because the multi-point focus has to be realized simultaneously to reduce the imaging. Finally, a bifocal wide angel lens antenna is designed successfully by using Geometric Optics (GO) method and commercial software MATLAB. And design method and final design parameters are also provided.Thirdly, as the focal pane imaging system, the geometry of feed is required to ease to integrate with others. To improve the resolution, the direction of feed must satisfy special conditions. This dissertation discusses common feed and studies on the E-plane taper rectangle dielectric rod, such as electromagnetic properties, design theory and techniques, and simulation methods.Finally, a simulation method-based on linear superposition is improved because it is difficult to simulate the lens antenna by using the electromagnetic-based methods. The condition that meets the linear superposition is discussed. The Amendment technique of the lens antenna structures is improved utilizing the simulated radiation pattern. |
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