【作者】 白文静；

【导师】 邱景辉；

【作者基本信息】 哈尔滨工业大学 ， 电磁场与微波技术， 2007， 硕士

【摘要】 副瓣电平是天线设计中的一个重要因素。当今,雷达面临各种复杂的电子干扰,其中雷达天线副瓣干扰是干扰的主要形式。其实不仅是雷达,强地物杂波背景下工作的反积极干扰和消极干扰、无源定位、抗反辐射导弹等都非常需要低副瓣天线。因此,目前国内外都在研制低副瓣天线。本课题所研究的半波振子馈电的带圆片副反射面的抛物面天线是一种尺寸小、重量轻、成本低、电性能良好的低副瓣天线。这种工作于短焦状态的抛物面天线不仅能在较宽的频带内实现低副瓣,在中心频带内具有极低副瓣特性,并且在保持副瓣电平很低的情况下,实现比较高的增益。这种结构和性能上的优势使该天线适用于生命探测雷达系统等需要的小尺寸低成本低副瓣天线的特殊场合。首先,简要介绍天线低副瓣的含义和划分标准,分析天线低副瓣的实现原理。然后分别讨论阵列天线和抛物面天线在实现低副瓣特性过程中需要解决的问题和解决途径,并以轴对称双反射面天线中最为典型的卡塞格伦天线为例分析影响副瓣的各种因素及其改进方法。其次,使用面电流元法分析当主反射面为抛物面时的口面场分布情况,建立了一个抛物面低副瓣天线的电磁仿真模型,并对该天线所使用的馈源的辐射特性进行了理论分析和电磁仿真,给出实际馈源方向性函数近似表达式并推导短焦抛物面的口面利用系数。最后,本文着重讨论焦径比和副反射面尺寸的变化对所研究天线副瓣电平的影响。通过CST-Microwave Studio?仿真软件进行仿真和分析,对于各种影响副瓣电平因素的重要性排序,给出降低短焦抛物面副瓣电平的途径,并依据理论分析和仿真优化,设计了一个成本低,体积小,尤其是纵向尺寸小,结构简单,电性能良好的低副瓣抛物面天线。更多还原

【Abstract】 The sidelobe level is an important factor in designing of antenna arrays. At present, the importance of sidelobe exceeds that of the gain and the main lobe width on a lot of occasions. There are a great number of interferences in radar communication, and the sidelobe interference is the main form of these. In fact, no only radar communication, the low sidelobe antenna is of great importance in anti-jamming technique both positive and negative with strong clutter back-ground, passive location and anti radiation missile as well. So a lot of researches focus on the low sidelobe antenna home and abroad.An S-band low sidelobe antenna is designed and proposed which fosters the character of small size and simple structure with wide bandwidth in this paper. The antenna to be discussed takes the advantage of short-focus paraboloidal reflector with round chip and is fed with half-wave dipole. Simulation results illustrate that the antenna satisfies the low sidelobe character through a wide frequency range. Besides, within the frequency range of the central frequency the antenna shows ultra-low sidelobe. At the same time, the collision between low sidelobe and beam width is solved successfully.At first, the meaning and standards of low sidelobe antenna are briefly introduced. The principles of the low sidelobe are analysed. The problems to be solved in the course of the realization method of the low sidelobe of array antennas and reflector antennas are pointed out, and the Cassegrain antenna is taken as an example to illustrate the affecting factors and the improvement on the method for the low sidelobe.Secondly, the aperture field distribution characteristics when the main reflector is a parabolic is analysed by current element methord. A simulation model of reflector low sidelobe antenna is set up.At last, the effects on the low sidelobe of the ratio of focal distancer and diameter and size change of assistant reflector have been discussed. The significance order of the factors affecting the low sidelobe is pointed out. Base on the theoretical analysis and simulation results, a low sidelobe antenna is designed which has small size and simple structure. The antenna contributes to the portable device for its short vertical length. Approximate calculation of radiation attribution of half-wave dipole feed with round chip is also discussed by simulation analysis, and the utilization coefficient of aperture field is derived.更多还原