具有最小阵元数目的近场稳健宽带的天线阵设计研究

Theories, methods and key technologies related to the near-field antenna system were studied in this project. First, for low signal to noise ratio and the slow scan time of scanning antenna system, adaptive beamforming is proposed to design and optimize antenna model, and in the design project SNR and scan time are taken as the optimization objective points. Within the loop antenna, based on near-field transmission model principle, the convex optimization criteria is used to design main lobe beam former and the mesh will be considered as the target area one by one within the loop antenna detection, scanning different grid for the region of the main lobe of the antenna array beamforming , each of the main lobe region are with the same convex optimization criterion, but with different antenna beamforming, the guidelines ensure that solving with a combination of beam scanning universal and personalized output. Provide a reference for the forming production of antenna to shorten the experimental time, reduce the cost of equipment. Second, the application of convex optimization criterion to establish a minimum number of array elements, the best array size and sensor position, the antenna system has a robust beamforming with a better feed system, to save space for the actual production. Finally, the broadband signal frequency based on convex optimization criterion of the same characteristics of antenna array design, for the array system operating frequency of occurrence of the offset, to provide the correct detection.

本项目针对近场天线系统所涉及到的理论，方法和关键技术进行研究。首先，针对目前天线阵检测信号信噪比低和扫描时间慢的缺点，提出以信噪比和扫描时间为优化目标，从自适应波束形成角度出发设计优化天线阵模型。该模型以环形天线内部近场传输模型原理为基础，首先对环形天线内部检测目标区域进行网格划分，然后应用凸优化准则扫描不同网格为天线阵波束输出的主瓣区域，每个主瓣区域均具有相同凸优化准则，但却具有不同天线波束输出，该准则保证求解出具有最优阵列指向性的波束输出。为天线的制作提供借鉴作用，缩短实验时间，降低设备成本。其次，应用凸优化准则建立具有最小阵元数目，最佳阵元尺寸及阵元位置的，得出具有最优阵列构型的天线阵系统，并且该天线系统具有稳健波束输出天线阵的馈电系统模型，为实际制作节省空间。最后，提出基于凸优化准则的宽带信号频率不变特性的天线阵的设计，为天线系统工作频率发生偏移时，提供正确的检测性。

本项目主要完成近场天线阵小型化的设计、稳定性能和宽带性能的研究。首先，利用优化方法针对环形天线内部的波束形成优化问题，对均匀圆形天线阵列、非均匀圆形天线阵列、均匀椭圆形天线阵列进行最小阵元数目的设计，并对窄带的最小阵元数目的天线阵列的稳定性能进行了研究。其次，分别采用凸优化和最小二乘法（LS）的宽带波束形成方法进行宽带性能设计，对基于SRV约束的LS算法的圆形阵列内部波束形成性能进行了验证，并提出了一种基于迭代变加权的改进算法有效的克服了其在个别来波方向无法有效实现波束形成要求的问题。再次，针对近场宽带信号波束形成中的噪声抑制问题进行了探讨，提出了一种结合SRV约束的LCMV宽带算法，讨论了SRV约束的施加范围对最终波束输出产生的影响。该项目得出具有最小阵元数目的天线阵系统，并且该天线系统具有稳健波束输出及宽带的频率不变性能，为实际制作节省空间，提供正确的检测性。