混合算法在稀布阵设计中的应用

提出把混合优化算法IGA-EDSPSO(Improved Genetic Algorithm-Extremum Disturbed Simple Particle Swarm Optimization)和基于RWG基函数的MoM-PO混合算法用于最小阵元间距约束的稀布阵列设计中.通过调整阵元间距来优化辐射阵因子,改善了阵列天线的辐射性能.与以前的方法相比,该方法在处理大型阵列时,降低了对计算机资源的需求,有效地实现了考虑互耦情况下副瓣电平的抑制,真实地考虑了天线的整个结构对于方向图的影响,对低副瓣电平阵列天线的设计有一定的指导意义和参考价值.     

基于自适应遗传算法的稀布阵天线优化

稀布阵能够以较少的天线单元,通过稀布的方式和先进的处理算法获得与传统等间距阵相当的孔径效能,降低了系统的硬件成本,具有灵活布置的优点、重要的研究意义和应用价值。稀布阵与同口径满布阵相比副瓣电平较高。文中提出了一种基于自适应遗传算法的稀布阵列综合优化方法。该算法采用实值编码方式,引入自适应遗传算子,有效提高了优化效率,避免陷入个体早熟及局部收敛,得到了更低的副瓣电平。给出了具体实现步骤以及仿真实例,结果表明,采用自适应遗传算法,得到了更低的稀布阵天线副瓣电平。     

非周期阵列天线辐射性能的研究

针对非周期大间距矩形阵列,运用遗传算法对其进行优化布阵和幅度加权,得到各阵元最佳的位置和幅度分布,使得阵列扫描范围内的副瓣电平最低。研究了阵元间距、阵列扫描范围、单元天线波束宽度等3种因素对阵列副瓣电平和增益的影响,得到了各因素对阵列辐射性能影响的规律。通过遗传算法优化得到了扫描范围内副瓣电平最低时的阵元间距,可用于指导工程设计。     

采用FFT-PSO策略的多约束稀疏阵天线方向图综合

采用稀疏布阵的相控阵测控天线,阵元等幅激励时的阵列峰值副瓣电平无法满足指标要求.在考虑天线增益、半功率波束宽度等指标约束时设计了合适的适应度函数,并基于粒子群算法(PSO)对阵元激励幅度进行优化以降低天线副瓣电平.同时,分析了等间距栅格平面阵列天线方向图与离散傅里叶变换的关系,采用快速傅里叶变换(FFT)降低了阵列方向图计算复杂度.仿真结果表明,该方法可有效降低峰值副瓣电平和计算复杂度.     

用遗传算法优化任意稀布率的平面阵列

通过给经典遗传算法(GA)的变异算子赋予新的功能,实现了任意稀布率的平面阵或线阵方向图的优化.研究了遗传算法参数和优化结果之间的关系,仿真结果表明,同时考虑峰值副瓣电平和波束宽度才能获得更满意的稀布结果.归纳得出一个平面稀布阵峰值副瓣电平的估计公式,并和随机稀布阵的公式进行了比较,数值结果表明该公式有一定的工程意义.     

基于改进遗传算法的非均匀稀布阵列优化

提出了一种对非均匀稀布阵列阵元间距进行优化的改进的遗传算法。该算法在编码时,将阵元间距依据尺寸步长划分为不同的节点,通过对节点的二进制编码,灵活实现带约束阵元间距的遗传编码。在遗传操作过程中,依据不同的进化阶段自适应设定算子系数,有效地提高了遗传算法的收敛性。文中采用同时考虑副瓣电平和渡束宽度的双适应度函数,使优化得到的天线阵列方向图比采用单适应度函数有较好的综合性能。最后通过大量仿真结果验证了这一算法的有效性。     

低峰值旁瓣电平稀布阵综合算法研究

针对稀布阵具有较高峰值旁瓣电平(PSLL)的问题,从阵元对称与否、阵元数奇偶及天线阵列有无栅瓣这三个角度分析、对比了粒子群算法和三种遗传算法进行稀布阵综合的优缺点,并进一步分析了阵元数目、阵列孔径和最小阵元间距对稀布阵PSLL的影响。为进一步降低PSLL,提出在适应度函数中加改进海明窗的方式进行稀布阵阵元位置优化,通过仿真验证了方法的正确性和适用性。     

基于改进麻雀搜索算法的稀布线阵综合方法

针对阵列天线中阵列孔径、阵元数目、阵元间距等多约束的稀布线阵综合问题,文中提出了一种基于改 进麻雀搜索算法的稀布阵列综合优化方法。给出了改进麻雀搜索算法的流程,并在确定阵列孔径、阵元数目和最小阵 元间距的约束条件下,采用Tent 混沌映射进行天线阵元位置的初始化,提高算法的搜索性和收敛性,实现了抑制天线 峰值旁瓣电平(PSLL)的稀布线阵综合仿真。仿真结果表明,所提出的方法相比于其它文献中的优化方法,能够得到更 低的峰值旁瓣电平,稳健性好,效率高。在仿真结果的基础上,引入实际天线进行组阵分析,验证了该方法的可行性。     

宽带稀布线阵的多约束优化设计

针对有阵列孔径、单元数、最小和最大单元约束的宽带稀布直线阵的综合问题,提出一种基于目标向量映射的差分进化算法。通过引入目标向量与需要布阵单元间距之间的映射关系,使单元间距的多约束转化为非约束优化问题,从根本上消除了优化过程中的不可行解,减小了布阵空间,降低了优化算法的计算量。以改善稀布线阵峰值旁瓣电平为目的进行仿真,仿真实验结果表明,稀布阵可以在给定的工作频段内有效的抑制阵列方向图的副瓣,能比现有方法处理更多的约束条件且算法具有好的收敛性和稳健性。     

利用稀布设计低成本单脉冲天线

根据某单脉冲天线要求,设计了一个稀布阵相控阵天线.通过对圆口径满阵阵面均匀抽取,减小了约30%的单元.在此基础上对剩余单元进行了30 dB的Taylor加权和30 dB的Bayliss加权,分别实现了和波束和方位面及俯仰面差波束,并比较了稀布阵与满阵的和差波束的方向图.仿真结果显示,该稀布阵符合设计要求,其和差波束的副瓣均高于满阵副瓣约5 dB,和波束主瓣3 dB波束宽度接近于满阵指标.该方法有效地降低了单脉冲相控阵天线的成本.     

矩形平面稀疏阵列的免疫算法优化

采用免疫算法来优化矩形平面稀疏阵列最大相对旁瓣电平,建立了基于免疫算法的克罗内克积形式矩形稀疏阵列模型,并进行了仿真实验,结果表明免疫算法能有效地降低矩形平面稀疏阵列的相对旁瓣。     

六边形平面天线阵优化稀疏布阵研究

本文首先对遗传算法进行改良,并精心设计了适应函数,以确保遗传算法快速收敛;然后,应用改良后的遗传算法对天线单元正三角形排列的六边形平面阵进行优化稀疏布阵处理,以改善其辐射特性.本文还研究了优化稀疏阵的频率特性,并提出了仅对阵列天线外边缘部分进行优化稀疏处理以达到改善整个阵列天线辐射特性的方法,该方法具有优化区间小和计算量少等优点,为以改善性能和降低造价为目的的大型阵列天线优化稀疏处理提供了一条有效途径.结果表明通过优化稀疏处理,六边形平面阵的辐射特性可以获得相当大的改善,天线阵的最大旁瓣电平降低了7.5~9.4dB,仅对阵列天线外边缘部分单元进行优化稀疏处理可以达到与对全部单元进行优化稀疏处理相同的性能改进.     

Aerial arrays with asymmetrical thinning

The use of asymmetrical element spacings in thinned aerial arrays is shown to give symmetrical radiation patterns. The use of asymmetrical element spacings gives lower sidelobe levels than symmetrical spacings. With an array of nine elements in a 19? array, the greatest sidelobe level is reduced from ?5.61 dB to ?6.87 dB by using an asymmetrical array instead of a symmetrical array.     

共享孔径同心圆阵稀疏交错优化布阵方法

同心圆阵列天线具有波束对称、360°方位角扫描、抗干扰能力强等优点，被广泛应用于星载、机载、舰载雷达及飞机声呐等领域。在天线孔径有限的情况下，如何进一步提高同心圆阵的孔径利用率，通过孔径的空分复用，设计出子阵稀疏交错分布的多功能同心圆阵列天线，具有较大的研究价值。利用均匀同心圆阵列天线激励与方向图函数存在二维傅里叶-贝塞尔变换关系，基于二维三次插值和密度加权，提出了一种同心圆阵稀疏交错优化布阵的方法。该方法通过对均匀同心圆阵列天线方向图采样值的频谱能量进行分析，采用三次插值的方法，实现了同心圆天线阵列方向图函数到同心圆阵元激励能量的映射转换；基于密度加权的原理，对排序后归一化阵元激励的奇偶交错选取，使得稀疏交错子阵方向图频谱能量均分匹配，实现了同心圆阵的稀疏交错优化布阵设计。仿真结果表明，该方法得到的交错子阵天线具有峰值旁瓣电平低、主瓣宽度窄且方向图性能近似程度高的优点，有效解决了同心圆阵列天线稀疏交错优化布阵的设计难题，实现了两子阵交错的共享孔径多功能同心圆阵列天线设计。     

运用遗传算法综合稀疏阵列

本文运用遗传算法(GA)综合稀疏阵列(单元从规则栅格中稀疏)时,不仅优化单元间距,而且将单元激励也作为优化变量,从而提供了更多的自由度来控制稀疏阵列的性能.其中,单元的幅相加权在数字波束形成天线中可以很容易通过数字方法实现.由于稀疏阵列间隔是栅格的整数倍,因此采用了GA结合快速傅立叶变换的方法加快阵列方向图的评估,提高了优化效率.     

Isophoric arrays-massively thinned phased arrays withwell-controlled sidelobes

Traditional filled phased arrays have an element placed in every location of a uniform lattice with half-wavelength spacing between the lattice points. Massively thinned arrays have fewer than half the elements of their filled counterparts. Such drastic thinning is normally accompanied by loss of sidelobe control. This paper describes a class of massively thinned linear and planar arrays that show well-behaved sidelobes in spite of the thinning. The term isophoric is derived from Greek roots to denote uniform weight. In isophoric arrays, element placement based on difference sets forces uniformly weighted spatial coverage. This constraint forces the array power pattern to pass through V uniformly spaced, equal, and constant values that are less than 1/K times the main beam peak, where V is the aperture size in half-wavelengths and K is the number of elements in the array. The net result is reduced peak sidelobes, especially when compared to cut-and-try random-placement approaches. An isophoric array will exhibit this sidelobe control even when the array has been thinned to the extent that K is approximately the square root of V. Where more than one beam must be generated at a time, isophoric array designs may be used to advantage even within a traditional filled array. By “interweaving” two isophoric subarrays within a filled array and by appropriate cyclic shifting of the element assignments over time, two independent antenna power patterns can be generated, each with a sidelobe region that is approximately a constant value of 1/(2K) relative to the main beam, where K is the number of elements in the subarray     

New Model for Synthesis of Symmetrical Thinned Linear Arrays

In symmetrical thinned linear arrays design, the positions of thinned array elements are very important for optimal performance in terms of its minimum peak side lobe level （Msli）. For the synthesis of thinned arrays with a given thinning rate, it would have almost the same Msll solution between taking only segmental aperture nearby both ends of the aperture into account and taking all the aperture into account. In this paper, the element distribution characteristic over the aperture of many optimum thinned arrays is studied, then the aperture release model is founded by the least square method to synthesize the thinned arrays. This model is vital for the computing burden alleviation and the efficiency optimization, and would hardly bring any degradation of the obtained array performance.     

New Model for Synthesis of Symmetrical Thinned Linear Arrays

In symmetrical thinned linear arrays design, the positions of thinned array elements are very important for optimal performance in terms of its minimum peak side lobe level (Msll). For the synthesis of thinned arrays with a given thinning rate, it would have almost the same Msll solution between taking only segmental aperture nearby both ends of the aperture into account and taking all the aperture into account. In this paper, the element distribution characteristic over the aperture of many optimum thinned arrays is studied, then the aperture release model is founded by the least square method to synthesize the thinned arrays. This model is vital for the computing burden alleviation and the efficiency optimization, and would hardly bring any degradation of the obtained array performance.