基于仅相位加权的阵列天线波束赋形优化方法

给出了一种仅改变相位分布的阵列天线波束赋形优化算法.在不改变阵列天线各单元的馈电幅度分布的前提下,为了使天线的辐射波束形成给定的方向图形状,采用联合应用DFP和BFGS公式的变度量优化算法对阵列天线各单元的馈电相位分布进行优化,使得优化后的阵列天线主波束形状能够与预给的波束形状吻合,从而达到设计要求.该方法为N维函数无约束极小值方法,具有快速收敛、计算量小的优点,是一种阵列天线波束赋形的通用方法.     

矩形耦合本振阵列接收波束形成

分析了耦合振荡器阵列的波束接收原理,以二维矩形耦合振荡器阵列为本振阵列,推导了产生均匀平面相位分布的控制方法,确定了波束形成的相位加权矢量,并通过仿真验证理论分析结果,为耦合振荡器阵列在天线接收技术的应用提供理论参考.     

相控阵天线外形优化缩减RCS研究

隐身武器平台对其装备的相控阵天线提出了超低RCS的要求,对影响相控阵天线RCS的因素进行了分析,对缩减RCS的各种措施进行了讨论。针对优化外形布局来缩减相控阵天线RCS,文中提出了一种差分进化算法,该方法用一组多项式描述天线阵列的外形轮廓,用差分进化算法对多项式的系数进行优化。该方法的目标函数可以根据需要灵活设置,最终得到的阵列外形连续,适合工程应用。并给出了1000 阵元阵列的应用实例,对仿真结果进行了分析。     

结合傅立叶变换的差分进化算法在阵列波束展宽中的应用

提出了一种新型阵列波束展宽的方法,使用差分进化算法结合傅立叶级数变换的初值对阵列波束进行展宽设计。与普通傅立叶级数变换法展宽波束相比,该方法获得主波束范围内的平坦度更好,且能得到更低的副瓣电平。推荐的方法还能避免传统差分进化算法收敛速度慢、易陷入局部最优的问题。文中使用该方法对一个21元的一维直线阵进行波束展宽优化设计。在等幅同相情况下,直线阵的3dB波束宽度为4.02o,使用推荐方法设计后,3dB波束宽度扩展到19.6o,主波束范围内的平坦度为0.21dB,证实了该方法的可行性。     

基于微分进化算法的综合孔径辐射计圆阵优化

依据二维综合孔径微波辐射计的反演成像原理及天线阵列分布的基本思想,引入微分进化算法优化设计圆周天线阵列分布.以阵列最小冗余及空间频率采样点均匀分布距离最大化为目标函数,得到了16～40个天线单元二维圆周阵列的优化分布结果.与常用的模拟退火算法相比,该算法的优化结果更优,计算时间更短.     

基站智能天线多波束合成技术

采用数字波束形成的技术，给出了基站智能天线多波束合成的有效算法。对圆环阵分布的基站天线多波束方向图进行了综合，得到了空间隔离度很好的多个波束，并将副瓣控制在30dB以下，结果令人满意。该方法可用于任意单元构成的不均匀阵列天线，还可用于波束展宽及扇形波束的合成。     

星载SAR波束展宽研究

该文提出了一种新型的混合遗传算法基于排序的主动变异型退火-遗传算法(AMAGA),描述了星载SAR天线部分单元仅相位加权波束展宽方法,并将量化效应考虑在内,避免了量化所带来的误差,计算结果可直接工程应用。部分单元仅相位加权波束展宽方法比满阵单元相位加权更具有可实现性和灵活性。文中给出波束展宽实例,宽波束主瓣内凹口可以控制,且波束具有较低的副瓣电平。     

一种基于DFP-BFGS算法的阵列天线波束赋形方法

为优化得到给定形状的目标方向图,引入了一种基于DFP-BFGS无约束最优化算法的数值方法.优化过程是先对阵列各单元的激励幅度和相位同时优化,然后对得到的阵列激励幅度数据进行部分调整,使其更加均匀以便于馈电网络的设计.最后固定激励幅度分布,仅对相位数据进行优化.在实现对方向图主瓣波束赋形的同时,得到了较为均匀的激励幅度分布.该优化方法具有应用灵活和结果可调控的优点,是一种实现阵列天线波束赋形的实用方法.     

一种低副瓣阵列天线指数幅度加权算法及仿真

在阵列天线的波束形成设计中,对波束的低副瓣设计提出了严格要求。提出了一种优化线阵列天线副瓣抑制的幅度加权的波束形成算法。通过此加权算法在小幅度展宽波束主瓣宽度的情况下,实现副瓣抑制高达30 d B的效果。并通过对多个不同单元数量的线阵列天线的方向图综合仿真计算,分析该算法参数对方向图的影响,该算法具有副瓣抑制效果好,简洁高效,易于工程实现等特点。     

有源天线阵波束电扫描新技术

研究了利用互注频锁相技术实现的低成本、高集成度、高效率的新型非线性有源天线阵列,给出了耦合振荡器阵列的幅度及相位动力系统满足的微分方程组,然后针对控制非线性有源天线阵列波束扫描这一实际应用,找到了可以实现有源天线阵列波束扫描的相位动力系统的轨道及振荡器自由振荡频率需满足的条件,并对轨道的稳定性进行了分析,提出了一种不用移相器实现非线性有源天线阵列波束电扫描的方法,最后利用计算机仿真验证了该方法的可行性.     

层析SAR系统基线优化设计

自然场景3维影像重构是层析合成孔径雷达(TomoSAR)的重要应用。传统方法在沿高程维进行层析处理时,均通过对等距线阵模型进行加权的方式,以主瓣展宽为代价来抑制方向图旁瓣水平。针对该问题,该文建立一种基于非等距线阵的峰值旁瓣比极小极大优化模型,即在约束主瓣宽度一定的情况下,通过阵元位置的优化配置来获取观测场景视角范围内任意指向的最优旁瓣水平;提出一种目标函数离散栅格化方法,进而采用序列二次规划(SQP)方法并结合差分进化算法特有的全局记忆能力,以获取最优阵元配置方案。对PolSARpro全极化层析SAR仿真数据的处理结果表明该方法能够有效地应用于自然场景的3维影像重构。     

Accurate evaluation for MDPSK with noncoherent diversity

The error probability analysis of M-ary differential phase-shift keying signals with noncoherent diversity combining over general fading channels is not available in the literature except for some simple cases. The difficulty lies in the philosophy which attempts to explicitly determine the phase distribution expressions of the received signal, and this often leads to a mathematically intractable issue. In this paper, we take a novel approach by formulating the phase distribution in terms of joint moment generating functions of the real and imaginary parts of the decision variable at the receiver output. We further derive fast convergent techniques for two-dimensional (2-D) inverse Laplace transform enabling us to accurately evaluate the phase distribution. The error probability formulas thus obtained involve a twofold integral, which can be efficiently evaluated by using our algorithms developed on the basis of the 2-D trapezoidal summation and Gauss-Chebyshev quadrature. The new technique is very general, taking into account the effects of arbitrary diversity order, symbol alphabet size M, and arbitrary diversity branches correlation. Numerical results are also presented for illustration.     

A Hybrid Method for Electromagnetic Propagated Resistivity Logging Data Inversion

Using an inverse technique for the array electromagnetic propagated resistivity logging (EPRL) data, a fine interpretation can be obtained about the resistivity distribution of an invaded profile. Generally, the Gauss-Newton algorithm (GN) is an efficient technique for the inverse problems; however, as a gradient-type optimization method, its accuracy and convergence depend strongly on the initial value. Even though this problem can be avoided by using a differential evolutionary algorithm (DE) as a global search optimization, it is computationally less efficient. In this paper, a hybrid inversion method of differential evolution has been developed to remove the strong dependence of the accuracy and convergence on the initial value. In this new method, an additional operation, which is designed with GN, is performed only to the best individual with a delay in the evolution processes of DE. Hence, the GN operation is used for the improvement of the convergence speed without leading to any decrease of the robustness of DE. The hybrid method is then extended to apply the inversion of EPRL data. Our results demonstrate its speed, steadiness, and efficiency of this hybrid method     

双瑞利分布的时空二维杂波模拟

本文讨论了一种幅度满足双瑞利分布，其二维谱和特征值谱给定的时空二维杂波的模拟方法，它对机载相控阵雷达系统的设计和性能分析是极有意义的。文中详细探讨了二维杂波模拟遇到的新问题，并提出检验二维杂波模拟结果的新要求。     

基于子阵划分的二维穿墙MIMO阵列设计

穿墙三维成像中,不同的阵列构架会直接影响阵列性能及其适用环境。利用等效阵列原理设计二维多输入多输出(MIMO)阵列,在具体分析一维STVA阵列具有最短物理尺寸的原理上,提出了利用子阵划分的方法解决等效阵列到MIMO阵列的去卷积问题。针对去卷积后得到多种MIMO阵列构型的择优问题,提出了综合尺寸的概念,利用子阵划分后的部分信息衡量去卷积后MIMO阵列的物理尺寸,最后将这种方法推广至二维MIMO阵列,设计出适用于穿墙成像的二维UWB-MIMO阵列,利用仿真实验验证了其在穿墙三维成像中的优异性能。     

基于改进差分进化算法的合成孔径圆阵优化

天线阵列设计是合成孔径辐射计的一项关键技术。圆阵可以实现零冗余基线分布,具有结构简单、 易于与平台共形等特点,是当前广泛关注和应用的合成孔径辐射计天线阵列形式之一。针对以u-v 覆盖均匀程度最 大化为目标的合成孔径圆阵优化问题,利用一个新的目标函数,提出了一种基于改进差分进化算法的优化方法. 新 的目标函数具有计算量小和u-v 覆盖均匀程度衡量精度高的优点,并且改进的算法可以保持种群规模。典型的数值 仿真结果给出了16 ~40 个天线单元的优化圆阵排列, 验证了本文方法的有效性。     

Implementation of a forward-backward procedure for the fast analysis of electromagnetic radiation/scattering from two-dimensional large phased arrays

Forward-backward method (FBM) was successfully developed for the analysis of electromagnetic radiation/scattering from one-dimensional (1-D) phased array in an efficiency appealing fashion. The FBM applications to treat 2-D array problems are developed in this paper. Acceleration algorithm, performing better than the novel spectrum acceleration algorithm used for 1-D FBM computation, is also developed for this 2-D FBM so the unique advantages of high efficiency and O(N/sub tot/) computational complexity as in the 1-D problems can be retained where N/sub tot/ is the total number of array element. Numerical examples are presented to demonstrate its validity.     

On the dynamics of two-dimensional array beam scanning viaperimeter detuning of coupled oscillator arrays

Arrays of voltage-controlled oscillators coupled to nearest neighbors have been proposed as a means of controlling the aperture phase of one-dimensional (1-D) and two-dimensional (2-D) array antennas. It has been demonstrated, both theoretically and experimentally, that one may achieve linear distributions of phase across a linear array aperture by tuning the end oscillators of the array away from the ensemble frequency of a mutually injection-locked array of oscillators. These linear distributions result in steering of the radiated beam. It is demonstrated theoretically that one may achieve similar beamsteering in two dimensions by appropriately tuning the perimeter oscillators of a 2-D array. The analysis is based on a continuum representation of the phase in which a continuous function satisfying a partial differential equation of diffusion type passes through the phase of each oscillator as its independent variables pass through integer values indexing the oscillators. Solutions of the partial differential equation for the phase function exhibit the dynamic behavior of the array during the beamsteering transient     

Beam reconfiguration of linear array of parallel dipole antennas through switching with real excitation voltage distribution

In this paper, authors propose a method based on the modified particle swarm optimization (PSO) for beam reconfiguration of linear array of mutually coupled parallel half-wavelength dipole antennas with real excitation voltage amplitude distribution. Two different beam pairs are generated, one pencil/pencil beam pair and another pencil/flat-top beam pair in the horizontal plane. One beam is changed to another through switching while sharing a common amplitude distribution. Two examples are presented, one without ground plane and another in presence of ground plane. Dipoles are connected to its feed network through a switch, so that it can be turned on or off, depending on the switch position. Beam reconfiguration is achieved by suitably turning the array elements on or off using same voltage excitation distribution. Modified PSO is used to compute the excitation voltages as well as the switching configuration for each pattern having a prefixed side lobe level. The current in the driven and parasitic elements is determined via induced EMF method considering the current distribution on each dipole to be sinusoidal. Proposed method efficiently synthesizes dual-beam switching the power pattern from pencil to pencil and pencil to flat-top having same or different side lobe levels using common excitation voltages. It calculates the maximum variation of the active impedance of driven elements and the power losses when the radiation patterns switch from one beam to another. The paper calculates the array directivity as the distances between antenna array and the ground pane varies. Three other state-of-the-art metaheuristics like differential evolution, gravitational search algorithm, artificial bee colony algorithm are also employed for achieving a comparative evaluation.