机载合成孔径雷达叠层宽带微带天线的研究

发布时间：2019-04-23 13:21

【摘要】：合成孔径雷达是一种高分辨率主动式成像雷达。除分辨率高外,合成孔径雷达还具有探测距离远,受光照、气象环境限制小,可穿透地物等特点。这些理想的特性,很大程度上与其天线性能相关,其分辨率、灵敏度、信噪比和探测距离等多个关键参数与天线的带宽、方向图、增益等参数有着直接的联系。提升雷达系统的性能,很重要的一部分工作是提升合成孔径雷达天线的性能。微带阵列天线是机载合成孔径雷达天线一种重要实现形式,对微带天线的研究是合成孔径雷达天线研究的一个重要方向。阻抗带宽较窄一直是宽带微带天线设计的瓶颈。利用叠层技术和缝隙技术等手段,可有效扩展天线带宽,但伴随而来的是方向图性能变差,出现最大增益方向零偏问题和副瓣、后瓣增大的问题。另外,机载天线的特殊结构要求,小型化雷达系统的迫切需求都给微带天线的小型化设计提出了更严格的技术要求。这些问题都是目前机载合成孔径雷达微带天线设计中亟待解决技术的热点、难点问题。本文首先结合叠层技术和缝隙技术,设计了 U型缝隙叠层微带天线,通过频带内多谐振点的设置,使阻抗带宽达到了 24.5%。在此基础上,利用缝隙贴片结构和表面电流的对称特性,对天线进行了小型化改进,设计了半U型缝隙叠层宽带微带天线,在阻抗带宽为19.5%的情况下,其平面面积相对于前者缩小了 29.1%。但在上述宽带天线设计和小型化设计的同时,天线方向图的性能并不理想,出现了旁瓣和后瓣过大,E面和H面方向图不对称,最大增益方向零偏等问题。针对此类问题,本文提出了一种非对称缝隙贴片投影修补法,优化叠层缝隙天线或缝隙天线的方向图。通过此方法,本文优化了 C型缝隙微带天线和半U型缝隙叠层微带天线两种天线结构,设计了倒置C型缝隙叠层微带天线和倒置半U型缝隙叠层微带天线,实验结果表明,结构优化后的天线的最大增益方向零偏问题和方向图对称性都得到了不同程度的改善。使用EBG结构可改善天线方向图性能。本文分别设计了小型化UC-EBG结构和小型化金属EBG结构,两种EBG结构小型化特征明显,带隙特性理想。将小型化金属EBG结构反射板应用于倒置半U型缝隙叠层微带天线阵,天线前后比得到了明显的改善。合成孔径雷达对于副瓣抑制比和增益等参数要求较高,微带天线一般都要采用阵列形式。本文使用文化算法对多条件下的超低副瓣阵列天线进行了综合。通过与其他传统算法和进化算法的对比,多方面验证了文化算法对于超低副瓣阵列天线方向图综合更为有效。最后,在上述研究的基础上,本文针对课题指标设计试制了一副机载合成孔径雷达用8单元倒置半U型缝隙叠层微带阵列天线,其增益达到16.12dB,主瓣宽度14Deg,副瓣抑制比达到20.12dB。
[Abstract]:Synthetic Aperture Radar (SAR) is a high resolution active imaging radar. In addition to the high resolution, SAR also has the characteristics of long detection range, limited by illumination and meteorological environment, and can penetrate into the surface and so on. Many key parameters, such as resolution, sensitivity, signal-to-noise ratio and detection distance, are directly related to the bandwidth, pattern, gain and other parameters of the antenna. To improve the performance of radar system, an important part of the work is to improve the performance of synthetic aperture radar (SAR) antenna. Microstrip array antenna is an important realization form of airborne synthetic aperture radar antenna, and the research of microstrip antenna is an important direction of synthetic aperture radar antenna research. The narrow impedance bandwidth has always been the bottleneck of broadband microstrip antenna design. By means of stacking technique and slot technique, the bandwidth of antenna can be expanded effectively, but accompanied by the deterioration of pattern performance, the problem of maximum gain direction zero bias and the problem of side lobe and rear lobe increase. In addition, the special structure requirement of airborne antenna and the urgent demand of miniaturized radar system put forward stricter technical requirements for miniaturization design of microstrip antenna. These problems are the hot and difficult problems in the design of airborne synthetic aperture radar microstrip antenna. In this paper, a U-shaped slot stacked microstrip antenna is designed with the combination of stacking technique and slot technique. The impedance bandwidth reaches 24.5% through the setting of multi-resonant points in the frequency band. On this basis, the miniaturization of the antenna is improved by using the symmetrical characteristics of slot patch structure and surface current, and a semi-U slot stacked broadband microstrip antenna is designed. The impedance bandwidth of the antenna is 19.5%. Its plane area is reduced by 29.1% relative to the former. At the same time, the performance of the antenna pattern is not ideal, such as too large sidelobe and rear lobe, asymmetry of E-plane and H-plane direction pattern, zero bias of maximum gain direction, etc., in the design of wide-band antenna and miniaturization, the performance of antenna pattern is not ideal, such as too large sidelobe and rear lobe. In order to solve this problem, an asymmetric slot patch projection repair method is proposed in this paper to optimize the pattern of laminated slot antenna or slot antenna. Through this method, the structure of C-slot microstrip antenna and semi-U-slot stacked microstrip antenna are optimized. The inverted C-slot stacked microstrip antenna and inverted semi-U-slot stacked microstrip antenna are designed. The experimental results show that: (1) the structure of C-slot microstrip antenna and semi-U-slot stacked microstrip antenna are optimized in this paper. The maximum gain direction bias problem and pattern symmetry of the optimized antenna are improved to some extent. The antenna pattern performance can be improved by using EBG structure. The miniaturized UC-EBG structure and the miniaturized metal EBG structure are designed in this paper. The miniaturization characteristics of the two kinds of EBG structures are obvious and the band gap characteristics are ideal. The miniaturized metal EBG structure reflector is applied to inverted semi-U slot laminated microstrip antenna array, and the front-to-back ratio of the antenna is improved obviously. Synthetic Aperture Radar (SAR) requires high sidelobe rejection ratio and gain, and microstrip antennas are usually in the form of array. In this paper, the cultural algorithm is used to synthesize the ultra-low sidelobe array antenna under multiple conditions. By comparing with other traditional algorithms and evolutionary algorithms, the cultural algorithm is proved to be more effective for the synthesis of ultra-low sidelobe array antenna pattern. Finally, on the basis of the above research, an 8-unit inverted semi-U slot stacked microstrip array antenna for airborne synthetic aperture radar is designed and manufactured in this paper. The gain reaches 16.12 dB and the main lobe width is 14 Deg. The sidelobe inhibition ratio was 20.12 dB.
【学位授予单位】：哈尔滨工程大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TN957.2

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