共查询到20条相似文献,搜索用时 125 毫秒
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在子阵级相控阵中,对于多波束形成等很多应用,需要在子阵级进行数字波束扫描。此时抑制扫描方向图的旁瓣是一个重要问题,而其关键在于构造有效的子阵级加权网络。该文将整个阵列作为一个超阵、将每个子阵作为一个超元来考虑,基于用超元方向图近似表示真实子阵方向图的处理思想,使得构造加权网络所需要的各矩阵的维数由原来与阵元数相同降低为与子阵数相同,从而可十分显著地降低运算代价;而且可得到波束形状、宽度及增益均很接近的新的子阵方向图。该方法可在一定程度上抑制子阵级波束扫描后的阵列方向图旁瓣。仿真结果证明了其有效性。 相似文献
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利用遗传算法(genetic algorithm, 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。提出了基于子阵级的波束扫描方法,在每个扫描分区内无需改变阵元权值,仅通过子阵级数字波束形成即可完成阵列的波束扫描,并分析了不同扫描角对阵列方向图的影响。为了抑制大扫描角带来的高旁瓣,运用自适应原理使子阵级方向图在高旁瓣位置形成凹陷。分析与仿真结果表明,该方法能够进一步提高阵列方向图的主旁瓣比,增加扫描分区的范围。 相似文献
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为了有效地降低阵列天线在数字波束形成过程中旁瓣水平,提出了一种通过二次组阵实现的低旁瓣自适应波束形成方法。在阵列相互重叠的子阵划分基础上,通过子阵对期望信号及干扰信号进行自适应波束形成,实现对期望信号的增益接收以及对干扰信号的深度抑制。在子阵数字波束形成的基础上,对各个子阵的输出运用二次组阵的方法,对二次组阵的方向图在约束条件下进行波束合成实现对子阵方向图中旁瓣的对消补偿,从而达到降低旁瓣的目的。通过理论分析和实验仿真表明,与常规LCMV方法相比,基于二次组阵的波束形成方法在保证了对干扰信号深度抑制的同时,有效地降低了方向图中的旁瓣水平,提高了系统的抗干扰性能。 相似文献
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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。 相似文献
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针对不规则结构阵列的波束图容易出现旁瓣升高的问题,该文提出了一种基于径向基神经网络(RBFNN)的波束设计方法。该方法根据Olen波束形成中阵元位置和阵列加权向量之间的非线性关系,利用径向基神经网络输入和输出之间的非线性映射特性,以任意结构阵列的实际阵元位置为基准,构造带有误差的阵元位置样本集。之后利用Olen法计算阵列加权向量并进行波束形成,当波束图满足设计要求时,记录对应的位置和阵列加权向量作为径向基神经网络训练数据的输入样本和输出样本,并使用训练后的网络得到实际阵列的加权向量。最后,对直线阵、弧形阵、随机环形阵进行了波束优化设计,结果这几种阵形的波束都可以满足设计要求,证明了所提方法的有效性。 相似文献
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A Technique for the Synthesis of Line-Source Antenna Patterns Having Specified Sidelobe Behavior 总被引:4,自引:0,他引:4
A new method for the synthesis of line.source antenna patterns having prescribed sidelobe envelope functions is discussed. The patterns obtained are inherently nonsupergained and, in the sense of Taylor patterns, approach the narrowest beamwidth for the given sidelobe behavior. Sample patterns and corresponding aperture distributions, together with required design parameters, are given. The sidelobe envelope functions for those patterns having maximum gain for a given maximum sidelobe level are also presented. 相似文献
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The constrained least squares (CLS) distribution is a method for obtaining distribution functions that yield low sidelobe patterns with specified constraints on the aperture efficiency, and are especially useful for the transmit patterns of active array antennas. The widely used Taylor distribution optimizes only pattern performance while the CLS distribution optimizes pattern performance while taking into account the constraints on both the peak element amplitude and the total effective radiated voltage (ERV) of the aperture distribution. The paper compares the pattern characteristics of linear arrays with CLS and Taylor distributions. The results help to establish guidelines on when a CLS distribution would be preferable over a Taylor distribution when a specified aperture efficiency is important. 相似文献
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The properties of a general class of monopulse antenna difference patterns which are obtained by differentiating a desirable class of antenna sum patterns are analyzed. Their corresponding aperture distributions are synthesized using the Fourier transform. It is found that of the general class of patterns considered, there is one family which gives the best compromise between slope at boresight and sidelobe level. Curves are presented which relate sidelobe level and slope at boresight for this particular family; these curves may be used to design monopulse difference patterns for either a specified slope at boresight or a specified sidelobe level. Simple expressions for the corresponding far-field difference patterns, their beamwidth, and their aperture distributions are given. 相似文献
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A new antenna pattern synthesis technique that allows the design of large planar antenna array radiating footprint patterns of a specified boundary with controlled ripple and sidelobe levels is presented. The method synthesises the desired footprint as a composition of a set of circular Taylor patterns appropriately weighted with the samples of the pattern obtained after stretching or shrinking a continuous circular aperture distribution developed by the Elliott-Stern method. A footprint of continental Europe radiated by a planar array with a large number of elements shows the technique's performance. The synthesis procedures were completed in about 1 s using a desktop computer. 相似文献
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Measurement distance effects on low sidelobe patterns 总被引:3,自引:0,他引:3
Because of the current strong emphasis on low sidelobe antennas, the effects of measurement distance in distorting patterns are reexamined. Previous calculations have used obsolete or suboptimum aperture distributions. The Taylorbar{n} linear distribution is a versatile highly efficient and robust optimum distribution; its use here allows a single curve of sidelobe measurement error versus measurement distance (normalized to far field distance2D^{2}/lambda ) for a given sidelobe level. The calculations give data from a uniform distribution to a 60 dB Taylor. For example, the first sidelobe of a 40 dB Taylor pattern is in error 1 dB at a distance of6 D^{2}/lambda . 相似文献
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A 1-parameter circular aperture distribution is described. It is analagous to the Taylor 1-parameter modified (sin x)/x line source. The new distribution allows aperture design and tradeoff studies to be easily made in terms of sidelobe ratio or edge taper; the distribution is efficient and of low Q. Both the distribution and its corresponding pattern are given by Bessel functions. A table of values of the parameter H, beamwidth, efficiency and edge taper are given against sidelobe ratio. 相似文献
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For fixed aperture size, the aperture taper which maximizes the power radiated into a specified interval (-theta_{0},theta_{0} ) is determined, and the properties of the corresponding pattern are compared to the ideal space pattern introduced by Taylor [1]. We consider the case of the linear aperture with no supergaining, although the results are directly applicable to the principal plane patterns of the two dimensional rectangular aperture. It is shown that for an aperture of widtha , as (pialpha/lambda )sin theta_{0} increases, one can not only maximize the power radiated into (-theta_{0},theta_{0} ), but also constrain the sidelobe ratio outside (-theta_{0},theta_{0} ) below a specified value. 相似文献
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Symmetrically shaped patterns, generated by real continuous linear apertures derived from Taylor distributions, resemble Taylor sum patterns in regard to the distance-dependence of their sidelobe heights. Their ripple shows negligible near-field degradation. If the aperture distribution is complex, however, the ripple and sidelobe levels show previously unreported degradation behavior, including a lowering of the first sidelobe level. 相似文献
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Ares F. Elliott R.S. Moreno E. 《Antennas and Propagation, IEEE Transactions on》1994,42(11):1509-1514
An antenna pattern synthesis technique is presented that permits the design of planar antenna arrays with footprint patterns of a specified boundary. This technique is applicable to planar arrays of a wide variety of grid structures and can produce patterns with controlled ripple and sidelobe levels. The approach involves two steps: the first consists in stretching the pure real-continuous aperture (an extension of circular Taylor distributions, developed by Elliott and Stern [1990]) into a distribution with a boundary that is inversely proportional to the flat-top beamwidth; the second is the minimization of a cost function (the square of the difference between the resulting power pattern and the desired one) using the Fletcher-Powell method. A square footprint, produced by a rectangular grid (obtained by sampling this distribution) with the corner elements appropriately removed, is presented as an illustration of the method 相似文献
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圆柱面上的轴向偶极子阵的低副瓣方向图优化综合 总被引:1,自引:1,他引:0
本文利用新的非线性最优化方法讨论圆柱面上的轴向偶极子阵的低副瓣方向图优化综合问题,利用阵列的单元可实现增益方向图,我们把阵列综合问题表述为一个约束非线性规划问题,采用新直接法求解该问题即可得出一组使阵列的总方向图满足副瓣指标要求,同时具有尽可能高的方向性系数的激励系数,如果阵列的总方向图不能达到副瓣指标,则可得出一组使阵列方向图在可达到的副瓣方向图综合设计的模拟计算结果。 相似文献