基于遗传算法的低副瓣阵列天线综合

为得到更低副瓣的方向图,建立16单元线天线阵和32×32单元面天线阵遗传算法模型,并对这两类阵列天线方向图进行综合。将综合仿真结果与Chebyshev、Taylor两种传统综合方法进行比较。比较结果表明,遗传算法优化方向图的第1副瓣电平可达-40dB,且优化效率比传统方法高很多。为遗传算法在阵列天线方向图综合中的应用提供了技术支持。     

增加主瓣增益控制的阵列天线方向图综合遗传算法

阵列天线方向图综合是针对阵列天线方向图进行的相关研究中的一项基础性的研究内容。不同的应用场景中不仅需要设计形式不同的天线阵列,更需要阵列天线方向图并根据不同的性能参数指标要求进行分析优化,从而获得符合使用要求的阵列方向图。针对传统阵列天线方向图综合算法在方向图综合过程中未考虑主瓣增益约束的问题,提出了一种用于阵列天线方向图综合的改进遗传算法。在经典遗传算法的基础上设计了新的适应度函数以满足特殊情况下对主瓣增益进行约束的需求;并在算法计算过程中增加了精英保留策略,设计了随进化代数改变的交叉、变异概率。经仿真实验,结果表明所提算法能够在阵列天线方向图综合时在保证主瓣方向上的增益满足要求的同时可以获得相对低的副瓣电平水平。     

基于遗传算法的深空探测天线综合

为了改善深空探测中共焦面阵列馈电抛物反射面天线的可视范围,提出一种基于遗传算法的扫描波束综合方法。基于物理光学法计算共焦面馈电阵中每个馈源照射反射面的次级远场方向图,利用遗传算法优化得到的权值对各次级方向图加权合成期望的波束。仿真和分析结果表明：提出的基于遗传算法的共焦面阵列馈电反射面方向图综合与传统共轭场匹配方法相比,可控制旁瓣电平,更精确综合出期望方向图,扩大深空探测天线的可视范围。     

基于改进遗传算法的圆阵稀布方法

由于圆形阵列所具有的特性,使其正得到日益广泛的应用,但是圆阵方向图却具有相对主瓣较高的旁瓣电平。为此,针对稀布圆形阵列的天线单元使旁瓣电平尽量降低的问题,应用改进的遗传算法,取角度差值为染色体的基因,进行阵列孔径、单元个数、最小间隔一定的稀布优化排列,减小了遗传算法的搜索空间,提高了搜索效率。仿真结果表明:该方法能有效提高收敛速度、降低圆阵的旁瓣电平。     

应用遗传算法进行阵列天线方向图综合

采用一种用于区间控制的遗传算法,该算法采用基于排序的十进制编码,并对遗传参数和遗传操作进行改进,较大地提高搜索效率,较好地克服早熟现象.它用于优化阵列天线方向图在个个给定入射波角度区间上的旁瓣电平.良好的计算实例表明遗传算法是解决此类问题的有效工具.     

基于混沌遗传算法的二维平面阵研究

针对一般均匀平面阵列方向图旁瓣较高的问题，利用传统遗传算法对均匀阵进行二维稀布排列，有效降低了旁瓣电平，但遗传算法收敛速度慢，容易陷入局部最优解。因混沌优化算法具有随机性、遍历性以及规律性的特性，把混沌优化算法引入到遗传算法中，利用混沌序列初始化种群，可提高遗传算法的收敛速度和获得全局最优解的能力。因此，提出一种基于混沌优化算法的遗传算法，并把该算法应用到二维平面阵天线设计中，该算法对天线阵的排布进行了优化设计。仿真结果显示混沌遗传算法的收敛速度有所提高，阵列天线的副瓣电平进一步降低，说明该方法具有一定的可行性。     

基于遗传算法和禁忌搜索的MIMO雷达天线布阵优化

研究MIMO雷达在发射、接收天线孔径长度和阵元数目固定等约束条件下的天线方向图综合。MIMO雷达采用稀布天线,为了克服栅瓣效应并且降低旁瓣电平,同时为了避免遗传算法早熟收敛,进入局部最优,提出了一种基于遗传算法和禁忌搜索的混合二次优化布阵方法。该方法为了保证系统最大自由度,引入了距离扰动,同时对发射天线和接收天线的位置进行两次优化,有效解决了MIMO雷达天线方向图综合中低旁瓣电平设计问题。仿真结果证明了所提算法的有效性和优越性。     

基于微遗传算法的稀疏天线阵列优化方法

为生成无栅瓣、高空间分辨率的方向图,均匀平面阵列使用的天线单元数量很多,实现难度和成本高。稀疏布阵只需要相对较少的单元数目,会出现旁瓣电平升高、测向模糊等问题。通过对天线阵列特性进行分析,以全向一致、无栅瓣、低旁瓣的高分辨方向图为目标,利用微遗传算法对多重圆环阵列单元的位置参数进行优化,性能分析表明综合出的多重圆环阵列具有方位角对称、旁瓣电平低、起伏小的特点,且该算法优化效率高、收敛速度快。     

阵列天线方向图仿真系统设计与研究

针对阵列天线的布阵问题,设计了一种阵列天线仿真系统,实现了阵列天线设计的可视化操作。通过设置阵元数、波长、阵元间距等天线相关参数,系统能够实现直线、平面、圆形和圆柱四类阵列天线的仿真分析。针对四类阵列天线稀疏布阵问题,系统采用遗传算法,对稀疏阵列天线的方向图特性进行研究。通过系统的仿真,用户可以直观地观察阵列天线方向图的变化,从而调整相关参数实现阵列天线方向图的优化设计。该仿真系统具有操作简单、页面简洁、交互性强等特点,能够支持和辅助用户分析与设计阵列天线。     

基于遗传算法的圆柱阵列稀疏方法

由于共形阵列所具有的特性,使其正得到日益广泛的应用,但其耗用较多的阵元,方向图具有相对主瓣较高的旁瓣电平。为此,针对基本的共形阵列——圆柱阵列的天线阵元,应用经典遗传算法,以阵元的工作状态为优化参量,对其进行稀疏。减少了阵元数量,仿真结果表明,该方法能有效地降低圆柱阵列的旁瓣电平。     

Reduction of sidelobe levels in interrupted phased array antennas by means of a genetic algorithm

Interruptions in the regular lattice of a phased array antenna can lead to elevated sidelobe levels in the resulting antenna pattern. A method for reducing the sidelobe level in such an array is presented, based on the use of a genetic algorithm that modifies the element weights in the array. Results are presented for both scanned and unscanned arrays. © 2007 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2007.     

A versatile pattern synthesis algorithm for circular antenna array

This article presents a versatile pattern synthesis algorithm for controlling the sidelobe level and nulling region for circular antenna arrays. Nonuniform fast Fourier transform using the min–max interpolation method is utilized to overcome the nonlinear feature of circular arrays. The major advantage of the proposed algorithm is low complexity, which is key for hardware implementation. Moreover, the proposed algorithm functions well in amplitude‐only pattern synthesis, which may be required for low‐cost array systems using attenuators instead of complete amplitude and phase adjustment modules. Additionally, element failure of antenna arrays can be minimized in practical operations by resynthesizing the pattern by using the remaining antennas to achieve satisfactory performance. Simulation results indicate the lower complexity and higher versatility of the proposed algorithm compared with the conventional methods.     

A linear antenna array failure correction using improved bat algorithm

The failure of antenna array elements causes disturbance in the sidelobe power level. In this article, an improved flexible approach that use bat algorithm is proposed and applied to solve the problem of antenna array failure by controlling only the amplitude excitation of array elements. An adaptive inertia weight approach is applied to the standard bat algorithm to improve the quality of the solution and the speed of convergence. The effectiveness of the proposed improved bat algorithm (IBA) is verified on different standard test functions. Numerical examples of element failure correction are presented to show the capability of this flexible approach in antenna array failure correction.     

Optimization of circular antenna arrays using the cuckoo search algorithm

This article presents a study of circular antenna array design and optimization using the cuckoo search (CS) algorithm. The goal of optimization is to minimize the maximum sidelobe level with and without null steering. The CS algorithm is used to determine the parameters of the array elements that produce the desired radiation pattern. We illustrated the effectiveness of the CS in the design and optimization of circular antenna arrays by means of extensive numerical simulations. We compared our results with other methods from the literature whenever possible. We presented numerous examples that show the excellent performance and robustness of the CS algorithm and the results reveal that the design of circular antenna arrays using the CS algorithm provides acceptable enhancement compared with the uniform array or the design obtained using other optimization methods.     

MIMO‐UWB smart antenna communication characteristics for different antenna arrays of transmitters

The channel capacity of indoor multiple‐input multiple‐output ultra‐wide band (MIMO‐UWB) transmission for smart antenna is presented. The genetic algorithm (GA) is used to synthesize the radiation pattern of the directional antenna array to maximize the capacity performance in indoor MIMO‐UWB communication system. Three types of antenna arrays such as circular shape, L shape and Y shape arrays are used in the transmitter and their corresponding capacity on several paths in the indoor environment are calculated. The UWB impulse responses of the indoor channel for any transmitter‐receiver location are computed by applying shooting and bouncing ray/image (SBR/image) techniques, inverse fast Fourier transform and Hermitian processing. By using the calculated frequency response, the capacity performance of the synthesized antenna pattern on MIMO‐UWB system can be computed. Based on the topography of the antenna array and the capacity formula, the array pattern synthesis problem can be reformulated into an optimization problem and solved by the GA algorithm. The GA algorithm optimization is applied to a high order nonlinear optimization problem. The novelties of our approach is not only choosing capacity as the cost function instead of sidelobe level of the antenna pattern, but also considering the antenna feed length effect of each array element. The cost function for the problem is nonsmooth and discontinuous with respect to the antenna pattern. It is difficult to solve by gradient methods, since the derivative is hard to derive. The GA algorithm is employed to optimize the excitation voltages and feed lengths for these antenna arrays to increase the capacity. The strong point of the GA is that it can find out the solution even if the performance index cannot be formulated by simple equations. Numerical results show that the synthesized antenna array pattern is effective to focus maximum gain to the LOS path for these antenna arrays. In other words, the receiver can increase the received signal energy to noise ratio. The synthesized array pattern also can mitigate severe multipath fading in complex propagation environment. As a result, the capacity can be increased substantially in indoor MIMO‐UWB communication system. The investigated results can help communication engineers improve their planning and design of indoor wireless communication. © 2012 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2013.     

Bit error rate reduction for circular ultrawideband antenna by dynamic differential evolution

The dynamic differential evolution (DDE) is used to synthesize the radiation pattern of the directional circular arc array to minimize the bit error rate (BER) performance in indoor ultrawideband (UWB) communication system. Using the impulse response of multipath channel, the BER performance of the synthesized antenna pattern on binary pulse amplitude modulation system can be calculated. Based on the topography of the circular antenna array and the BER formula, the array pattern synthesis problem can be reformulated into an optimization problem and solved by the DDE algorithm. The novelties of our approach are not only choosing BER as the object function instead of sidelobe level of the antenna pattern but also considering the antenna feed length effect of each array element. The strong point of the DDE algorithm is that it can find out the solution even if the performance index cannot be formulated by simple equations. Simulation results show that the synthesized antenna array pattern is effective to focus maximum gain to the line of site path which scales as the number of array elements. In other words, the receiver can increase the received signal energy to noise ratio. The synthesized array pattern also can mitigate severe multipath fading in complex propagation environment. As a result, the BER can be reduced substantially in indoor UWB communication system. © 2011 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2012.     

Investigations on low sidelobe characteristics of reflectarray antenna for W‐band wireless sensor application

A W‐band low sidelobe level offset‐fed reflectarray antenna is designed, fabricated, and measured. Compared to conventional offset‐fed reflectarray antenna, the sidelobe level of proposed one is decreased significantly when the inclination angle of reflector is half of the incident angle of the feeding. At the same time, a large‐radiation‐area element is used to obtain low sidelobe level for the offset‐fed reflectarray antenna because of its large radiating element area and low specular reflection. A 52 mm× 180 mm offset‐fed reflector antenna have been designed and measured to verify the availability. From 90 to 96 GHz, measured results show that a maximum gain of 36dBi at 93 GHz, and the peak sidelobe level of 18dBc can be obtained with the proposed architecture.