基于凸优化的共形阵二维波束优化算法研究

传统波束优化手段应用于共形阵二维波束优化时,存在旁瓣水平高的问题。文中基于凸优化理论,提出了两种适用于共形阵列二维波束旁瓣优化的二阶锥规划方法。第一种是设定主瓣宽度下的最低旁瓣波束形成,第二种是设定期望旁瓣级的高增益等旁瓣波束形成。仿真结果表明相比于常规波束形成和其它波束优化方法,第一种方法在相同主瓣宽度约束条件下可以得到最低的旁瓣级,第二种方法得到的旁瓣级可以满足设定要求且有更高阵增益。     

一种低旁瓣数字波束形成方法

线性约束最小方差准则(LCMV)在波束形成技术中得到了广泛的应用.但是,很多情况下,它会产生偏高旁瓣.本文基于多线性约束最小方差准则,提出了一种降低旁瓣的波束形成算法.该算法通过搜索技术寻找到已形成波束图的最高旁瓣点,建立对应方向矢量上的增益方程,将其添加到原来的LCMV准则约束条件中,然后利用多线性约束最小方差准则进行权值更新,实现旁瓣的降低.该算法不仅适用于均匀阵列,还适用于非均匀阵列,仿真结果表明了该算法的正确性和有效性.     

基于DDS和Taylor加权发射波束形成研究

提出了一种对水声换能器基阵的发射波束进行优化控制的方法。首先,根据Taylor加权的计算公式,计算出可获得低旁瓣波束各阵元的幅度加权系数;然后,应用直接数字频率合成(DDS)技术设计出每个阵元偏移一定相位的发射信号;最后,结合高性能现场可编程门阵列(FPGA)技术,设计了8元直线阵的发射波束形成。仿真计算和实验结果表明,文章设计的方法不仅能实现低旁瓣的发射波束,还能很精确地控制发射波束角度,为以后的实际工程实现提供了参考方案。     

数字波束形成技术在智能天线中的应用

研究了波束形成算法在智能天线中的应用,包括直接加权波束形成算法、旁瓣抑制波束形成算法和零点抑制波束形成算法。在研究各种算法的基础上给出了仿真结果,并对比了每一种算法。详细分析了每一种算法的特点及适用条件,为波束形成算法在智能天线中的应用提供了技术参考。     

非线性有源天线阵接收技术研究

利用注入耦合振荡器阵列直接实现非线性接收波束合成,具有旁瓣低的优点,但难以实现接收波束扫描.因此提出了一种非线性有源天线阵接收的新技术,采用耦合振荡器阵列作为本振对接收信号进行混频,在中频进行波束合成.由于阵列单元间相位差可控,能实现接收波束扫描,还可用于生成和差接收波束.实验表明该技术可用于构建非线性有源天线阵的接收系统.     

基于微波光子的光学波束合成理论与仿真

光学波束合成技术是利用光信号作为载波携带射频信息而实现的一种新型的宽带射频波束合成技术,即用光信号来传输以及分配射频信号,实现射频信号的光波控制.文章介绍了基于微波光子的光学波束合成原理,重点介绍了光非相干和光相干波束合成架构,通过详细的理论公式推导以及软件仿真,表明上述两种光学波束合成架构可对多天线接收信号实现信号合成.针对目前大阵列天线单元系统对光学波束合成技术的迫切需求,利用光相干和非相干波束合成的各自优势,提出了一种适用于千量级天线阵列规模的光学波束合成架构,为光学波束合成技术在相控阵雷达、电子对抗等领域的应用提供解决方案.     

耦合本振阵列的旁瓣抑制技术研究

论文以耦合振荡器阵列作为本振阵列,提出天线阵列接收波束具有旁瓣抑制的扩展结构,推导了其接收波束形成的方向图函数,分析了该接收波束旁瓣抑制技术的可行性,并通过计算机仿真验证了旁瓣抑制技术的理论分析结果,为耦合振荡器阵列在接收技术上的应用提供了理论基础。     

基于二次组阵的低旁瓣波束形成方法

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。     

基于凸优化的最小旁瓣恒定束宽时域宽带波束形成

 提出了基于凸优化的适用于任意结构基阵的最小旁瓣恒定束宽时域宽带波束形成方法.首先将基阵波束响应表达成一组有限脉冲响应(FIR)滤波器权值的线性函数,然后采用基于恒定束宽限制条件的最小旁瓣优化准则设计FIR滤波器权值.同时对滤波器系数进行范数约束以及对干扰方向设置展宽零陷来提高波束形成器的鲁棒性.将期望波束响应的设计过程与实际波束响应的逼近过程融合在一起进行优化搜索,获得了全局最优解.该波束形成器设计问题被转化成凸优化问题求解,仿真结果验证了所提方法的有效性.     

基于二阶锥优化方法的MIMO阵列发射方向图设计

由于MIMO 阵列发射方向图通常是由期望方向图优化出信号协方差矩阵来实现,其方法运算量大且算法性能依赖参数选取等。该文提出利用基于二阶锥优化(second-order cone programs)方法的主瓣宽度约束条件下最低旁瓣波束形成构造出一组较低旁瓣的基波束,在集中式MIMO阵列的任意发射方向图可以由一组基波束合成的基础上,应用线性规划方法快速求解出构成发射方向图的基波束的比例系数。该方法设计的方向图具有更低的旁瓣和更加平滑的主瓣指向,仿真结果证实了方法的有效性。     

基于副瓣峰值控制的天线阵方向图综合

在干扰入射方向,自适应天线阵方向图会产生零陷,使副瓣电平降低。根据自适应阵列的这一特性,应用一种基于最大输出信噪比准则的改进自适应算法对天线阵进行方向图综合。假定有大量干扰信号施加到方向图副瓣区,通过只对副瓣峰值电平进行控制调整加权值,降低副瓣电平,得到满足副瓣要求的目标方向图,使算法得到简化。可以应用于不等间距直线阵列和矩形平面阵的方向图综合问题。考虑了阵元间的互耦及阵元方向图特性的影响。仿真结果证实了该算法是可行的。     

Pattern synthesis in small phased arrays using adaptive arraytheory

A pattern synthesis technique for low sidelobe difference and scanned beams in small phased arrays is presented. The approach is based on adaptive array theory and is a development of a technique used for beam synthesis in an ideal, λ/2 spaced, isotropic array. The method has been applied to measured element pattern data from a five element linear array, which includes the effects of pattern corruption by mutual coupling. The successful synthesis of low sidelobe sum and difference beams are demonstrated, with the look direction on and scanned off boresight     

Planar antenna pattern nulling using differential evolution algorithm

Differential evolution algorithm is used for the pattern synthesis of planar antenna arrays with prescribed pattern nulls by position-only and position-amplitude optimization. The position-only optimization for a planar array allows null synthesis in any prescribed direction. For planar antenna array thinning it is necessary to use position-amplitude optimization for problems involving more than two nulls.     

A numerical pattern synthesis algorithm for arrays

A numerical technique for pattern synthesis in arrays is presented. For a given set of elements, the technique allows one to find a set of array coefficients that steer the main beam in a given direction and yield sidelobes meeting a specified criterion, if such a set of array coefficients exists. If the pattern specifications cannot be met with the given elements, the algorithm finds the best attainable pattern. The advantage of this technique is that it can be used with an arbitrary set of array elements. Different elements in the array can have different element patterns, and the array can have arbitrary nonuniform spacing between elements. The synthesis technique is based on adaptive array theory. The given array elements are assumed to be used as the elements of an adaptive array. The main beam is pointed in the proper direction by choosing the steering vector for that direction, and the sidelobes are controlled by introducing a large number of interfering signals at many angles throughout the sidelobe region. The algorithm iterates on the interference powers until a suitable pattern is obtained     

Difference pattern synthesis in small planar phased arrays

A pattern synthesis technique for low sidelobe arbitrarily scanned difference beams in small planar phased arrays is presented. The approach is based on adaptive array theory and is the development of a technique used for radiation pattern synthesis in linear arrays. The method has been applied to measured element pattern data from a small planar array, which includes the effects of pattern corruption by mutual coupling. The successful synthesis of low sidelobe difference beams is demonstrated, with arbitrary difference plane and scan angle     

Analysis of an over-constrained adaptive array

In antenna arrays, the number of nulls that can be formed independently is equal to or less than the number of array elements minus one. Therefore, if the number of interferences exceeds the number of freedom for pattern synthesis in adaptive arrays, nulls in the radiation pattern can not be steered toward each interference direction. To clarify the behavior of the adaptive array in such an environment, an analysis is made for the case where two interferences are impinging on the two-element directionally constrained adaptive array. As a result, it is proved that the adaptive array acts to reduce the undesired noise power at the array output. However, improvement in output signal-to-noise ratio is insufficient because of the limitation in null formation.     

Linear programming from generalised scattering matrix analysis of array for minimum sidelobe level and prescribed nulls

A pattern synthesis technique for arbitrary planar arrays which are characterised in terms of a generalised scattering matrix and whose radiated field is expressed as a spherical mode expansion is introduced. The procedure yields the complex-valued excitations to achieve a minimum-maximum sidelobe level given a specified pointing direction and mainlobe width, as well as prescribed field nulls. All inter-element coupling effects coming from complex radiating structures used as array elements are inherently taken into account. Numerical results are presented for arrays of dielectric resonator antennas.     

一种新的低副瓣曲线阵数值综合方法

本文提出了一种新的低副瓣曲线阵数值综合方法。把曲线阵综合问题表述为约束非线性最优化问题,利用新直接方法求解它,即可求出使阵列的总方向图满足特定的副瓣电平指标,且具有尽可能高的方向性系数的激励和空间分布,文中主要给出了自由空间曲线阵综合的数学模型和计算结果,并给出了直线阵时新综合方法与Taylor分布的比较结果。新综合方法也适用于共形曲线阵综合问题。     

Synthesis of near-field patterns of arrays

A new technique of synthesis of near-field (NF) amplitude and phase patterns of linear, planar, of volume arrays of finite size or arrays located on a planar contour of finite size is presented. The array could consist of point dipoles or directive elements. The criterion for prescribing the NF (amplitude and phase) pattern information in the synthesis problem for unique determination of array excitation currents is also stated. The proposed near-field synthesis technique is based on the potential integral solution of source currents, Nyquist sampling of the near-field data and the technique of linear least square approximation (LLSA). The NF pattern synthesis technique is illustrated to synthesize a variety of NF patterns with a number of array configurations. Application of the proposed NF pattern synthesis technique to minimize distortion in far-field patterns of arrays mounted on a conducting platform and to realize array antennas with low sidelobes in the near and far field is also presented.     

基于改进黑洞算法的阵列天线方向图综合

提出一种基于改进黑洞算法的阵列天线方向图综合方法, 在可控吸收率的基础上实施后向学习机制, 增加种群多样性以避免早熟收敛.针对基本黑洞算法在局部搜索方面的不足引入爬山搜索算子, 增加个体搜索深度以提高寻优效率.将所提算法应用于稀疏天线阵和等距非均匀天线阵的方向图综合, 仿真结果验证了所提算法解决该类问题的有效性.