双频阵列天线方向图的非线性最小二乘法综合

研究了一种20GHz和30GHz双频六角形阵列天线方向图的综合方法.采用了非线性最小二乘法对影响天线方向图的诸多参数,如单元的幅度和相位、单元间距以及单元在阵中的位置进行了优化设计,以使双频阵列方向图在最小二乘意义上逼近预先给定的理想方向图.仿真结果表明该方法可行、有效.     

采用非线性最小二乘法实现圆环天线阵的方向图综合

为使阵列天线获得圆对称方向图,通常采用环阵的排列方式。本文研究了圆环阵列天线的特殊方向图综合方法,文中采用非线性最小二乘法对影响天线方向图的诸多参数,如单元的幅度和相位、单元间距以及单元在阵中的位置进行了优化设计,使阵列方向图在最小二乘意义上逼近预先给定的理想方向图。仿真结果表明该方法可行、有效。     

基于非线性最小二乘法的阵列天线综合

将改进非线性最小二乘法应用到同心椭圆环阵列天线综合当中,通过优化同心椭圆环阵列天线阵列单元的激励幅度和相位,得到满足要求的辐射方向图。通过严格的数学推导,得到满足非线性最小二乘法的数学表达式,使得优化过程进一步简化。文中介绍的方法能够快速实现同心椭圆环阵列天线的优化,同时改变了传统非线性最小二乘法对初始条件敏感的缺点。     

采用非线性最小二乘法实现双频圆形天线阵的方向图综合

研究了20GHz和30GHz双频段圆环阵列天线的方向图综合方法。采用了非线性最小二乘法对影响天线方向图的诸多参数，如单元的幅度和相位、单元间距以及单元在阵中的位置进行优化设计，以使双频段阵列方向图在最小二乘意义上逼近预先给定的理想方向图。仿真结果表明该方法可行、有效。     

耦合激励系数及对称振子阵列天线的有源方向图研究

为了深入探讨相控阵天线单元间的耦合对阵中单元方向图的影响,以阵列天线单元S参数为基础,给出了阵列天线单元的耦合激励系数计算公式,利用阵列天线单元间的耦合激励系数分析计算阵中单元的有源辐射方向图. 同时利用矩量法分析由偶极子单元组成的阵列,并把阵列中每个单元的感应电流幅度和相位与耦合激励系数的幅度和相位进行比较,二者数据基本一致. 矩量法计算的单元有源方向图与本文提出方法的计算结果吻合良好,验证了本文给出的阵列耦合激励系数及阵列天线阵中单元有源方向图计算方法的可靠性.     

阵列天线相位中心的计算与分析

为了得到阵列天线的相位中心,本文从阵列天线的场表达式推导出阵列天线远场区的相位方向图与选取的参考点之间的关系式。并根据该关系式,应用最小二乘法得出了求解阵列天线的视在相心的方法。结合得出的结论,对一个矩形平面阵进行了仿真实验,实验证实了本方法的有效性。同时发现,阵列单元在不同角域内对应的视在相心不同,并且阵列天线的视在相心主要取决于阵列单元在相应角域内的视在相心。     

某相控阵天线幅相分配网络的设计与实现

在某相控阵天线设计中,需要对铅垂放置的天线单元的方向图赋形.本文采用最小二乘法得到天线单无各振子电流的幅度和相位,并用MATLAB进行方向图计算仿真;根据计算结果,设计了幅相分配网络,并用HSFF仿真软件进行模型仿真;应用矢量网络分析仪对实物进行测量.测量结果表明,天线单元铅垂方向图与计算、仿真结果一致,满足设计要求.     

基于NUFFT方法的二维非周期阵列天线方向图计算

相控阵天线应用在有限电扫描角度时,采用大间距体制以减少有源通道数量,降低天线成本。由于单元间距大于波长,在可视空域内会出现栅瓣,常采用非周期排列方法分散栅瓣能量降低栅瓣电平。文中提出了一种变距平移错位抑制大间距阵列栅瓣的方法,并介绍了基于二维NUFFT计算该非周期排列阵列天线方向图的方法。分析了影响该算法精度的因素,并通过在拟合虚拟阵列幅相值时通过采用局部坐标系有效减小计算量。通过一个由300个单元组成的非周期阵列方向图计算,对二维NUFFT方法以及累加法进行对比。前者的计算时间仅为后者的0. 9% ,验证了算法的高效性。计算结果显示全空域方向图吻合度高,方向性系数误差仅0. 05 dB,最高副瓣误差仅0. 12 dB,验证了算法的准确性。     

稀疏共形阵列天线方向图综合

提出一种基于多任务学习的共形阵列天线稀疏优化方法.该方法在考虑单元方向图的全局旋转变换和单元极化状态差异的情况下,建立了共形阵列天线导向矢量模型,结合多任务学习框架,以均匀分布共形阵列天线同一平面上阵元的方向图作为目标任务进行学习,通过稀疏向量支撑区的识别,将欠定的阵列流形矩阵方程转换为超定的特征矩阵方程进行求解,在实现阵列方向图逼近的前提下,建立了共形阵列天线阵元激励与位置联合稀疏优化的多任务学习模型.通过分块坐标下降法对稀布共形阵列天线多任务学习模型进行求解,实现了共形阵列天线的稀疏优化布阵.理论分析与实验仿真证明,该方法能有效减少共形阵的单元数量,简化共形阵列天线结构,获得与均匀分布的共形阵列天线性能一致的天线方向图,解决了稀疏共形阵列天线方向图综合优化设计难题.     

最小二乘恒模算法在阵列天线技术中的应用

介绍一种用于阵列天线，利用信号恒模特性进行自适应波束形成的算法，即最小二乘恒模算法。它通过对阵列天线单元接收信号进行非线性处理，在保持期望目标信号的同时，可在多个干扰方向形成零陷，从而大幅度提高信干噪比(SINR)。文章通过对该算法的仿真对其性能进行了分析，最后阐述了基于该算法的阵列天线应用。     

Reducing the Number of Elements in a Linear Antenna Array by the Matrix Pencil Method

The synthesis of a nonuniform antenna array with as few elements as possible has considerable practical applications. This paper introduces a new non-iterative method for linear array synthesis based on the matrix pencil method (MPM). The method can synthesize a nonuniform linear array with a reduced number of elements, and can be also used to reduce the number of elements for linear arrays designed by other synthesis techniques. In the proposed method, the desired radiation pattern is first sampled to form a discrete pattern data set. Then we organize the discrete data set in a form of Hankel matrix and perform the singular value decomposition (SVD) of the matrix. By discarding the non-principal singular values, we obtain an optimal lower-rank approximation of the Hankel matrix. The lower-rank matrix actually corresponds to fewer antenna elements. The matrix pencil method is then utilized to reconstruct the excitation and location distributions from the approximated matrix. Numerical examples show the effectiveness and advantages of the proposed synthesis method.      

Synthesis of linear antenna arrays using Z transforms

It is well known that a linear antenna array with equally spaced elements can be represented by a polynomial whose roots correspond to the nulls of its antenna pattern. Since the linear array has equally spaced elements, its polynomial has only integral powers of the variable, so that the array can be represented by aZtransform. Therefore, the effect of moving roots of the polynomial can be represented as a linear sampled-data system problem, which is solved by using a table ofZtransforms or by discrete numerical convolution. In this paper, the quantitative effects on the array and its antenna pattern caused by moving roots of the polynomial are determined, and these effects are utilized for array synthesis to produce desired antenna patterns. Examples illustrating the use of this new synthesis technique include modification of a uniform array to obtain low sidelobes in the antenna pattern and synthesis of an array to produce nulls in its antenna pattern in the directions of discrete and spatially distributed interference sources.     

基于孔径长度域重采样的快速恒定束宽波束形成

为解决宽带阵列天线波束宽度抖动的问题,在分析阵元权系数和阵列方向图傅里叶变换关系的基础上,提出了一种基于孔径长度域重采样的快速恒定束宽宽带波束形成方法。该方法通过期望方向图的傅里叶反变换获取孔径长度域上的权系数曲线,然后用不同的采样间隔对该权系数曲线进行重采样得到不同频率下的阵元权系数。由于仅需进行一次积分运算,该方法具有运算量小、速度快的特点。为使阵列方向图在恒定束宽的基础上具有更好的方向性,通过对孔径长度域拟合度的分析给出了期望方向图的设计方法。仿真结果表明所提方法可以快速形成方向性较好的宽带阵列恒定束宽方向图。     

基于粒子群算法的天线阵方向图优化

雷达阵列天线常涉及方向图综合，而天线阵综合常常是利用优化算法优化单元幅相及间距等参数的过程。粒子群算法具有理论简单、参数少和易于实现等特点，文中基于这一简单易行的优化算法，给出一种阵列天线赋形波束综合方法。通过优化阵列天线中各单元的馈电幅度和相位同时实现主瓣的赋形和副瓣电平的抑制，或通过仅相位加权实现主瓣波束赋形，得到优良的余割平方赋形。通过实例设计验证了粒子群算法优化天线阵方向图的有效性。     

基于框架理论的最小阵元数稀疏阵综合算法研究

随着越来越高的角度分辨率要求与进一步降低的天线成本,大规模阵列越来越普及。在重量、体积和成本有限时,要获得大孔径天线得到较高的角度分辨率,且尽量减少天线阵元数目,可采用最小阵元稀疏阵设计方法。本文基于框架理论,提出了一种新的最小阵元数的稀疏阵综合方法。该方法将稀疏阵设计问题转化为压缩感知问题模型,然后利用次优反馈的零空间追踪硬阈值算法求解。该方法可同时综合阵元位置与阵元权重来匹配给定的阵列方向图,并可有效降低阵元数。仿真实验证明了算法的正确性和有效性     

Features of formation of the patterns of a monopulse active phased array antenna with a dome lens

A method for the control of the transmission coefficients of antenna elements of a system comprising an active phased array antenna (APAA) and a dome lens, which ensures formation of a deep boresight null of the elevation difference pattern, is proposed. The effect of the control method on the characteristics of receiving monopulse channels of the APAA depending on the intrinsic noise of antenna elements is analyzed. The results of the well-known theory of reception of a nonplane wave by an antenna with continuous aperture are extended to the case of an array antenna.     

Model-based synthesis of shaped-beam patterns with the minimum number of elements: a state-space method

Conventional antenna array synthesis methods can give good performance for uniform spaced antenna arrays within desired performance bounds. However, due to the restriction of uniform antenna element spacing, a lot of elements are required. Because of the above-mentioned drawback, in this paper, a new approach is presented to synthesise uniform spaced antenna array using the minimum number of elements. This approach introduces the state-space model to represent the desired discrete array pattern that is sampled uniformly from ?1 to 1 corresponding to 0–180°, then uses the desired sampled array pattern directly to construct the forward–backward data matrix that is introduced to estimate the model parameters, from which the locations and excitations of the new antenna elements can be extracted. The appropriate roots that are located on the unit circle are selected to obtain new radiation pattern. Simulation results show the viability for both shaped-beam and pencil-beam designs.