阵列雷达最优子阵划分研究

在大型的相控阵天线中,为降低系统复杂性及应用成本,需要采用子阵划分技术对天线阵面进行最优划分。首先总结了基于子阵划分的相控阵雷达信号处理流程,在此基础上,从低副瓣的多波束、子阵级自适应干扰抑制等不同方面研究子阵划分技术。对现有子阵划分的研究途径、划分的方法以及各自特点进行研究和归纳。在抑制波束旁瓣方面,建立了求解最优子阵划分的优化数学模型;在自适应抗扰方面,分析了栅零点等影响子阵级自适应处理性能的因素。最后提出了最优子阵划分问题的进一步研究方向。     

一种降维空时自适应处理子阵划分方法

针对机载预警雷达降维空时自适应处理的子阵划分问题,提出了一种基于蚁群算法的雷达阵面子阵划分方法。该方法在子阵数给定的情况下,以最大化子阵级空时自适应处理的改善因子为优化准则,利用蚁群算法搜索子阵间的分隔点,从而获取最优的子阵划分方式。子阵划分是一种组合优化问题,蚁群算法非常适合于解决这种问题。仿真结果表明,利用该方法划分子阵并进行子阵级空时自适应处理,其改善因子总体上仅比阵元级的约低2dB,空时自适应方向图无明显的栅瓣,副瓣也较低。     

子阵平滑对小快拍数下CAB算法的改善

研究了子阵空间平滑自适应阵列方法对CAB算法性能的改进。数字波束形成是DBF雷达实现的关键技术。在诸多数字波束形成算法中，由于CAB算法在较高信干噪比条件下具有较快的收敛速度，因此具有较强的优势。但是该算法在较少的快拍数情况下不能保证在输出SINR收敛并趋向于最优值的同时保持较低的自适应旁瓣电平。因此，采用空间子阵平滑方法并利用子阵级自适应处理结构来等效提高CAB算法的快拍数，从而抑制干扰和噪声。仿真结果证明了该方法的有效性。     

基于STAP 杂波抑制的子阵优化技术

新一代相控阵雷达的天线阵列规模庞大,一般含有几百乃至上万个阵元。在阵元级实现自适应波束形成抗干扰和空时自适应处理杂波抑制,会极大地增加系统开销,甚至难以实现。在实际应用中,考虑到系统成本、信号处理运算量等因素,需要将大型阵列划分为适当的子阵,以减小接收所需通道数。文中通过子阵优化划分数学建模,研究子阵划分对干扰、杂波抑制性能的影响,探索最优子阵划分的数学求解方法,为大型阵列雷达研制提供理论支撑和工程可实现算法。     

平面数字阵列雷达的子阵级波束形成算法

大规模平面数字阵列雷达因为其优点得到广泛应用,但其全自适应处理实现困难,实际中广泛采用部分自适应处理,子阵结构就是其中的一种重要方法。该文针对有幅度加权的均匀平面阵,以各子阵噪声输出功率相等为原则进行非均匀邻接子阵划分,并通过归一化算法保证各子阵噪声功率相等,进而对平面阵子阵结构的波束形成性能进行了研究。计算机模拟仿真结果表明,该子阵结构的二维相扫和一维相扫的自适应方向图保形良好,可以达到与全自适应相接近的干扰抑制性能。     

基于聚类算法的最优子阵划分方法研究

 系统研究了大型阵列雷达中的最优子阵划分问题.分析了权矢量逼近准则下最优子阵划分方法的理论基础,得出最优子阵划分方案是否具有邻接性的判断依据,同时提出了一种新的子阵划分方法.与传统的基于聚类算法的子阵划分方法相比,新方法能够进一步减少权矢量逼近误差,获得更优的波束性能.在给定面阵结构及和差波束形成框架下,对提出的新方法进行仿真分析,并与两种传统的子阵划分方法相比较,验证了新方法的有效性.     

域子阵分解数字化阵列雷达的时空自适应处理

鉴于现役雷达系统硬件的限制，大型相控阵雷达的数字式自适应波速形成通常在子阵上完成。从长远观点来讲，技术进步将使得研制“子阵数字化阵列雷达”（EDAR）成为可能，尽管这未必导致自适应处理一定要在子阵上来完成，自适应处理计算要求很高，随数字通道数量的立方而变化。因此，它将限制所用数字通道的数量。但是，如果对子阵进行数字化，就可随意地选择“自由度”（DOF）较低的方案，以使自适应波0束形成的性能最佳化。现已表明，使用“域子阵分解”（DF）的DOF较低方案可在载机截获强杂波（AI）的环境中改善其性能[2,3,4]。在本中，我们把在[2]中论述的DF技术扩展到“时空自适应处理（STAP）”，并论证了由于主波束和强、弱杂波所导致的模糊慢速运动目标的探测。     

非均匀邻接子阵结构划分方法研究

子阵级的自适应处理可以用小代价获得比较好的处理性能,对于大型面阵的数据处理,提出了一种方法来划分非均匀子阵。计算机仿真结果表明,这种子阵结构的自适应方向图不但没有栅瓣,而且其主副瓣差值可以达到30dB以上,并可以在干扰方向和杂波处形成了很深的凹口。     

一种低旁瓣子阵级自适应波束形成方法

相控阵雷达在军事上的应用日渐广泛,要满足雷达系统性能日益增长的需求,必须采用大孔径天线,以便得到更高的角度和距离分辨率。大型面阵的全自适应波束形成计算量庞大,采用子阵级自适应波束形成可以用较小的代价实现较优的自适应性能。研究了等幅平面阵的子阵级波束形成技术,并针对非均匀划分的子阵结构,采用了子阵级通道噪声功率的归一化处理。该方法不仅能够有效降低子阵级方向图的旁瓣电平,其自适应性能保持良好。仿真验证了该方法的有效性。     

相控阵雷达干扰抑制的子阵结构

本文考虑的问题是在子阵波束形成的多功能相控阵雷达中应如何配置自适应干扰抑制,并且还考虑了旁瓣对消器和子阵级的最佳处理方法。子阵级的最佳处理从其工作性能和实际应用来看具有很显著的优点。本文主要讨论如何配置子阵的问题。     

An optical subarray antenna having antenna nulling applications

A linear subarray type optical antenna is considered for adaptive applications. The antenna has a small number of subarrays whose radiation patterns cover the region occupied by targets and interference in a near-optimum fashion. The subarray design is such that very low subarray pattern sidelobes are produced, thereby allowing operation in the presence of additional strong interference outside the subarray beams. The design of a near-optimum sheet metal antenna to perform these functions is described and the performance is analyzed.     

Reduced-rank adaptive detection of distributed sources using subarrays

We introduce a framework for exploring array detection problems in a reduced-dimensional space. This involves calculating a structured subarray transformation matrix for the detection of a distributed signal using large aperture linear arrays. We study the performance of the adaptive subarray detector and evaluate its potential improvement in detection performance compared with the full array detector with finite data samples. One would expect that processing on subarrays may result in performance loss in that smaller number of degrees of freedom is utilized. However, it also leads to a better estimation accuracy for the interference and noise covariance matrix with finite data samples, which will yield some gain in performance. By studying the subarray detector for general linear arrays, we identify this gain under various scenarios. We show that when the number of samples is small, the subarray detectors have a significant gain over the full array detector. In addition, the subarray processing can also be successfully applied to the problem of detecting moving sources in an underwater acoustic scenario. We validate our results by computer simulations.     

电子对抗环境下ADBF相控阵雷达的阵列结构优化

ADBF相控阵雷达通常采用子阵结构。子阵结构对系统性能具有显著影响,对相控阵进行最优子阵划分具有重要的理论与应用意义。该文利用多目标进化算法(MOEA)进行子阵结构优化,使系统在主瓣干扰下具有尽可能好的抗干扰及和、差波束旁瓣抑制性能。将和波束自适应方向图的旁瓣电平、系统输出SINR及差波束的旁瓣电平作为优化目标,构造了5种目标函数。给出了MOEA子阵结构的编码方法。基于Pareto秩排序的MOEA将3032的平面阵划分为64个子阵的仿真结果表明,系统的多种性能得到了提高。     

相控阵-MIMO雷达发射波束形成

对MIMO雷达提出了一项新技术——相控阵-MIMO雷达。该技术充分利用了MIMO雷达和相控阵雷达相干处理的优点,其实质就是把发射天线分隔成多个子阵,每个子阵发射相互正交的波形,通过设计每个子阵的加权矢量使天线在空间形成波束,并且每个子阵可以构成MIMO雷达模型。仿真分析表明：和相控阵和MIMO雷达相比,提出的相控阵．MIMO雷达具有更优越的性能。     

平面阵子阵级自适应波束形成方法研究

利用遗传算法(GA)将大型阵列划分为非均匀邻接子阵,以主旁瓣比作为适应度函数,并对遗传操作增加约束条件,得到具有栅瓣抑制能力的子阵结构。为进一步抑制平面阵俯仰和方位上的高旁瓣,对平面阵进行两级子阵划分,使平面阵方向图在俯仰和方位上均具有良好的主旁瓣电平比;为消除非均匀子阵结构各子阵通道噪声功率不同对子阵级自适应波束形成算法的影响,通过对阵列协方差矩阵进行奇异值分解、重构特征子空间,提出了基于特征空间重构的子阵级自适应波束形成方法。仿真结果表明了该方法的可行性与有效性。     

On the coherent interference suppression using a spatiallysmoothing adaptive array

The behavior of a spatially smoothing adaptive array is examined. An expression for the weight vector is first derived. Using the array gain on the desired signal and the coherent interference is obtained. Then the expression for output signal-to-noise (SNR) is derived. It shows that the performance of the spatially smoothing array depends on the number of the subarrays, the angle separation, relative power and initial phase difference between the desired signal and the coherent interference. For good interference suppression it is found that the magnitude of the phase difference of the incident and interference signals must be greater than the beamwidths of both the subarray and the equivalent array. There is also a tradeoff between increasing the groups of subarrays and decreasing the number of elements in the subarrays. Computer simulation results are given that validate the analysis     

Subarray design for adaptive interference cancellation

A method for designing near optimal, tapered subarrays for adaptive interference cancellation is proposed. The design method simultaneously produces a complete ordered set of fixed beam definitions, or nonadaptive weight vectors. The designer may choose to implement the first K of these if he or she wishes to have exactly K adaptive weights. In other words, the digital-adaptive processing is done in beam space, such that the beams are designed using the proposed method. To facilitate an RF implementation of the nonadaptive beamformer, each auxiliary beam uses only a designer-specified number of the elements in the aperture, thereby reducing the number of waveguide connections required. This design approach is fundamentally different from conventional subarray design approaches in that the new designs utilize cost functions related to interference cancellation.