【作者】 张悦；

【导师】 胡飞；

【作者基本信息】 华中科技大学 ， 信息与通信工程， 2017， 硕士

【摘要】 综合孔径辐射计(ASR)是一种利用小口径天线阵列来实现大口径观测的高分辨率成像系统。天线阵列是ASR的重要组成部分,其排布形式决定了空间频率域的采样分布,进而影响反演图像的质量,因此,阵列排布的研究是ASR的关键内容之一。本文研究了圆环区域约束的格点阵列排布方法,主要内容如下:针对原始圆环格点阵列的构造缺陷(部分阵元数的无空洞阵列不存在),提出了一种基于约束松弛的圆环格点阵列排布方法。首先分析圆心位置对阵列结构的影响,松弛圆心位置的区域约束,以圆环区域内的格点数为目标函数,采用模拟退火方法得到最优的圆心位置。在此基础上,以阵元数为目标函数,分别采用模拟退火和微粒群方法寻找最小阵元无空洞阵列,并进一步比较了两种算法的性能。数值仿真结果表明,该方法能够克服原始圆环格点阵列的构造缺陷,而且对应的无空洞阵列阵元数更少,可减少硬件成本。灵敏度是表征ASR性能的重要指标,本文提出了基于灵敏度最优的圆环格点阵列方法。首先定义广义圆环格点阵列,通过灵活调整内外圆环半径、最小阵元间距和阵元数满足具体应用需求。然后分析了退化因子与灵敏度的关系,进而以退化因子为目标函数,分别采用基于贪婪算法的逐步构造方法和基于模拟退火的搜索方法,寻找灵敏度最优的广义圆环格点阵列,并对优化结果进行了比较分析。最后,仿真验证了通过改善退化因子来实现灵敏度最优圆环格点阵列的有效性。更多还原

【Abstract】 Aperture synthesis radiometer(ASR)use small aperture antennas,which equivalent to large one,to achieve radiation signal imaging with high spatial resolution.Antenna array is an important part of ASR.Topology of array determines the sampling distribution of spatial frequency domain and the quality of image.The study on topology of array is a key subject of ASR.In this dissertation,array configurations in constraint annular section are studied.The main contents are as follows:A constraint relaxation method is proposed to design circular lattice array(CLA)because of original CLA’s constructive disadvantages that not all non-hole CLA configurations exist.The affection of relative position is analyzed by varying circle center’s position.This letter relaxes circle center’s constraint and also proposed a fitness function used to optimize its position with simulated annealing.A filled CLA configuration is obtained through the optimized circle center.Simulated annealing and particle swarm optimization are proposed to optimized element positions chosen from filled CLA without holes.The comparison of two methods’ performance is carried out.CLA using constraint relaxation could feed previous drawback.Corresponding array configurations also have less element numbers,which can save hardware costs.Sensitivity is an important performance parameter of ASR.In this paper,CLA based on optimum sensitivity is proposed.Firstly,general CLA(GCLA)is defined.The application requirement could satisfy by adjusting radii of two circles,minimum interval of elements and element numbers flexibly.Then,the relationship between degradation factor(DF)and radiometric sensitivity is analyzed.Taking DF as function,two methods are applied to find optimum sensitivity: greedy constructive algorithm and simulated annealing stochastic approach.Numerical results of two methods are carried out.Finally,simulated results verified effectiveness of this method,i.e.achieving optimum sensitivity of GCLA by minimizing DF.更多还原