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.     

Design optimization of circular antenna arrays using Taguchi method

This paper presents the application of Taguchi method (TM) to design optimization of non-uniform circular antenna array (CAA) for suppression of sidelobe levels (SLLs). TM, a robust design approach, takes signal-to-noise ratio and orthogonal array tools from the statistical design of experiments. These tools allow instead of full factorial parametric analysis minimize the design parameters; thus, increase the convergence speed and generate more accurate solutions. TM is used to determine an optimal set of amplitudes and positions of CAA for 8, 10, and 12 elements. Comparison of the results of the TM with those of latest meta-heuristic algorithms in the literature reveals that the CAA design with TM provides the best SLL reduction performance in all cases.

     

A new hybridized backtracking search optimization algorithm with differential evolution for sidelobe suppression of uniformly excited concentric circular antenna arrays

In this work, a hybridized combination of backtracking search algorithm (BSA) with differential evolution (DE) is proposed and applied on sidelobe suppression problem of uniformly excited concentric circular antenna arrays (CCAA). Each array is assumed to have isotropic elements and be placed on x‐y plane and has one center element. A search for optimal setting of ring radius and number of elements in each ring is carried out so as to achieve low sidelobe performance on overall azimuth plane. Care has been taken so that directivity does not get degraded as far as possible. Before applying this algorithm to CCAA design problem, BSA and the hybridized algorithm BSA‐DE are tested on five complex benchmark functions. Based on 30‐independent runs for each benchmark function, Wilcoxon's pairwise signed ranks test is utilized to judge the relative search performance of these two algorithms. The hybridized algorithm proves its superiority on almost all the considered benchmark functions. For the CCAA design problem dealt with in this work, BSA‐DE shows its superiority on one or both pattern parameters as well as structural parameters. © 2014 Wiley Periodicals, Inc. Int J RF and Microwave CAE 25:262–268, 2015.     

Synthesis of thinned concentric circular antenna arrays using teaching‐learning‐based optimization

In this article, the design of thinned concentric circular antenna arrays (CCAAs) of isotropic radiators with optimum side lobe level (SLL) reduction is studied. The newly proposed global evolutionary optimization method; namely, the teaching‐learning‐based optimization (TLBO) is used to determine an optimum set of turned ON elements of thinned CCAAs that provides a radiation pattern with optimum SLL reduction. The TLBO represents a new algorithm for optimization problems in electromagnetics and antennas. It is shown that the TLBO provides results that are somewhat better than those obtained using other evolutionary algorithms, like the firefly algorithm and biogeography based optimization. © 2013 Wiley Periodicals, Inc. Int J RF and Microwave CAE 24:443–450, 2014.     

A parallel implementation of seeker optimization algorithm for designing circular and concentric circular antenna arrays

In this paper, a parallel version of seeker optimization algorithm (SOA) is proposed for designing circular and concentric circular antenna arrays with the low sidelobe levels at a fixed beamwidth. The SOA is a relatively new evolutionary optimization algorithm based on the concept of simulating the act of humans’ intelligent search with their memory, experience, and uncertainty reasoning. In this work, The SOA has been parallelized by benefiting from its dividable population form. The numerical results show that the design of circular and concentric circular antenna arrays using the parallel SOA provides good sidelobe levels with a fixed beamwidth. The quality of results obtained by the parallel SOA is checked by comparing with those of several evolutionary algorithms in the literature.     

Wideband linear microstrip array antenna with high efficiency and low side lobe level

In this letter, the design and fabrication of the linear microstrip array antenna by series fed are presented. The array antenna consists of 16 reflector slot‐strip‐foam‐inverted patch (RSSFIP) antennas. The gain and efficiency of the linear array antenna is 16.6 dBi and 61% at 10 GHz, respectively. The antenna has a bandwidth (BW) of 45% from 8.1 to 12.8 GHz (S₁₁ < ?10 dB) and side lobe level (SLL) of ?25.6 dB across the BW of 19.2% from 9.4 to 10.4 GHz. These are achieved by using a microstrip series fed with defected ground structure (DGS) to feed the patch array antenna. Good agreement is achieved between measurement and simulation results.     

采用改进型SOS算法的光伏组件模型参数辨识

针对当前大部分光伏（photovoltaic,PV）模型参数辨识算法均存在准确性低和可靠性差等问题,提出了一种采用改进型共生生物搜索算法（symbiotic organisms search,SOS）的光伏组件模型参数辨识方法。首先,为提高标准SOS算法的寻优性能,提出了新的改进型SOS算法,记作ImSOS算法。该算法在标准SOS算法的生物种群初始化阶段采用了准反射学习机制;在互利共生搜索阶段采用了改进受益因子策略;在偏利共生搜索阶段采用了收缩随机数产生因子区间策略。其次,给出了采用ImSOS算法求解基于实验测量电流—电压（I-V）数据的光伏组件模型参数辨识问题的具体步骤及实现流程。最后,利用实际Sharp ND-R250A5光伏组件进行实验,通过与标准SOS算法以及其他七种新颖智能优化算法进行对比验证,结果表明了ImSOS算法在光伏组件模型参数辨识的有效性和优越性。可见ImSOS算法为准确可靠地辨识光伏组件模型参数提供了一种新的有效方法。     

Synthesis of sparse planar antenna arrays with multiple constraints

Synthesis of symmetrical sparse planar antenna arrays is introduced in this paper. In order to reduce the peak sidelobe level of the radiation pattern, the element positions of the arrays are optimized by invasive weed optimization with complex boundary conditions. The proposed algorithm changes a two‐dimensional optimization problem into a linear problem, which will reduce the complexity of the optimization procedure. The optimization method can constrain the size of the array aperture, the element number of the array, and the minimum spacing of the adjacent elements simultaneously. The simulation results show the robustness and effectiveness of the proposed method.     

基于旋转学习策略的共生生物搜索算法

为提高共生生物搜索算法(Symbiotic Organisms Search, SOS)的性能,提出一种基于旋转学习策略的共生生物搜索算法(Symbiotic Organisms Search Using Rotation-Based Learning, RSOS)。该算法将串行个体更新方式改为并行种群更新方式,提高算法收敛速度;引入遍历保优的旋转学习策略,代替寄生机制的盲目随机搜索,增大保留新个体的概率,补充种群多样性,提高算法跳出局部最优的能力。对于8个标准测试函数仿真表明,RSOS算法较基本SOS算法在收敛速度、收敛精度及稳定性上得到了明显提升。     

A survey of symbiotic organisms search algorithms and applications

Nature-inspired algorithms take inspiration from living things and imitate their behaviours to accomplish robust systems in engineering and computer science discipline. Symbiotic organisms search (SOS) algorithm is a recent metaheuristic algorithm inspired by symbiotic interaction between organisms in an ecosystem. Organisms develop symbiotic relationships such as mutualism, commensalism, and parasitism for their survival in ecosystem. SOS was introduced to solve continuous benchmark and engineering problems. The SOS has been shown to be robust and has faster convergence speed when compared with genetic algorithm, particle swarm optimization, differential evolution, and artificial bee colony which are the traditional metaheuristic algorithms. The interests of researchers in using SOS for handling optimization problems are increasing day by day, due to its successful application in solving optimization problems in science and engineering fields. Therefore, this paper presents a comprehensive survey of SOS advances and its applications, and this will be of benefit to the researchers engaged in the study of SOS algorithm.

     

稀疏同心圆阵旁瓣电平优化设计

稀疏优化后的同心圆阵的旁瓣电平虽然相比于满阵有所降低,但还是很高。为了获得具有更低旁瓣电平的同心圆阵,本文采用锥型波束形成技术,对利用模拟退火粒子群算法得到的稀疏同心圆阵加窗,优化阵列馈电电流的激励振幅。利用改进的三角窗、汉宁窗和布莱克曼窗三种窗函数对稀疏同心圆阵进行优化。仿真结果表明,加窗后,稀疏同心圆阵的旁瓣电平都有明显降低,采用布莱克曼窗得到的阵列的最大旁瓣电平最小,汉宁窗的次之,三角窗的最大。     

A dual‐band microstrip antenna using a circular ring and a concentric disk

A dual‐band microstrip antenna using a differentially driven annular ring and a single‐ended concentric circular disk is reported. The ring is designed in the TM₁₂ mode at a lower frequency f_l and the disk in the TM₁₁ mode at a higher frequency f_h. It is found that the mutual loading perturbs the resonant frequencies and thus the outer and inner radii of the ring and the radius of the disk calculated from the cavity models need to be slightly adjusted. More importantly, it is also found that the mutual loading affects the gains and may reduce the gain of the disk antenna substantially. The cavity‐model design formulas to determine the ring and disk dimensions are modified to account for their mutual loading between the ring and disk. It is shown that the differentially driven ring has an improved current distribution, a better impedance matching, and an enhanced impedance bandwidth. Moreover, a higher gain is obtained for the disk. A design sample for f_l = 2.45 GHz and f_h = 5.3 GHz on an FR4 substrate was fabricated. Simulated and measured results agree satisfactorily. © 2016 Wiley Periodicals, Inc. Int J RF and Microwave CAE 26:268–276, 2016.     

Design of circular patch antenna with a high gain by using a novel artificial planar dual‐layer metamaterial superstrate

This study presents a new dual‐layer metasurface structure proposed to enhance the performance of a circular patch antenna. A novel unit cell planar metasurface is characterized by nearly equal enhanced effective permeability and permittivity ε_r ? μ_r > 1 at the resonant frequency. In addition, a 5*5 array of these unit cells are used as a superstrate over a circular patch antenna which is fed by 50 Ω microstrip line and operating at 2.45 GHz for improving the antenna performance. The patch antenna gain is increased by creating an in‐phase electric field area on the top surface of the metasurface. The obtained results showed that the maximum gain of the antenna increased from 2.31 dBi to 7.5 dBi. A 30% increase in the bandwidth is also remarked. The proposed antenna with metasurface occupies an overall volume of 1.01λ_g ×1.01λ_g ×0.025λ_g . The simulation analysis and measured results were performed using the microwave studio, high frequency structure simulator software, and vector network analyzer. The proposed antenna prototype has been fabricated. The measured results indicate that the antenna has a good impedance matching in the desired operating band (2.37‐2.49 GHz) with the resonant frequency of 2.44 GHz which make the proposed antenna appropriate for microwave applications.     

Oppositional symbiotic organisms search optimization for multilevel thresholding of color image

Selection of optimal threshold is the most crucial issue in threshold-based segmentation. In case of color image, this task is become challenging, because conventional color image segmentation has computational complexity and also it suffers from lack of accuracy. Various techniques such as threshold based, region growing, edge detection, graph cut, pixel classification, neural network, active contour, gray level co-occurrence matrix are proposed so far for image segmentation in the literature. Out of them, threshold-based segmentation is popular for its simplicity. To address the problem of color image segmentation, we propose an enhanced version of metaheuristic optimization algorithm called Opposition based Symbiotic Organisms Search (OSOS) to solve multilevel image thresholding technique for color image segmentation by introducing opposition based learning concepts to accelerate the convergence rate and enhance the performance of standard symbiotic organisms search (SOS). The performance of the proposed OSOS based algorithm is investigated thoroughly and compared with some existing techniques like Cuckoo Search (CS), BAT algorithm (BAT), artificial bee colony (ABC) and particle swarm optimization (PSO). The comparison is made by applying the algorithm to a set of color images taken from a well-known benchmark dataset (Berkeley Segmentation Dataset (BSDS)) and some of the color images collected for the COCO dataset. It is observed from the results that the performance of the OSOS based algorithm is promising with respect to standards SOS and others in terms of the values of objective functions as well as the values of some well-defined quality metrics such as peak signal-to-noise ratio (PSNR), structure similarity index (SSIM) and feature similarity index (FSIM). The results of the proposed algorithm may encourage the scientists and engineers to apply it into pattern recognition problems.     

To reduce side lobe level of slotted array antennas using nonuniform waveguides

In this article, a method is presented to reduce the side lobe level of slotted waveguide array antennas while the gain to be constant. In this method, the H‐plane dimension of the waveguide is considered as the variable rather than constant. The nonuniformity of waveguide walls obviates the need for offset of slots and thereby reduces the side lobe level of radiation pattern. A slotted nonuniform waveguide is designed at frequency 10 GHz and then fabricated and tested. © 2015 The Authors International Journal of RF and Microwave Computer‐Aided Engineering Published by Wiley Periodicals, Inc. Int J RF and Microwave CAE 26:42–46, 2016.     

Serial‐feed for a circular patch antenna with circular polarization suitable for arrays

A compact sequential‐rotation array with serial feed and three probes using multi‐layer substrate is proposed. The most compact shape for the microstrip patches are selected with the optimization for the axial ratio and return loss bandwidth. The gain, return loss, and axial ratio bandwidths of the antenna are improved significantly by converting three patches to one circular. The patch radius and the position of probes are selected to form circular Poynting vectors around it where the maximum power is present at large frequency range. While the two layers of the structure use similar board this structure only uses a substrate and three simple pins. Also the total area of the antenna is limited to the microstrip patch and it has a straightforward fabrication steps. So the wideband antenna is relatively inexpensive and compact. The antenna has 21.4% 3 dB axial ratio bandwidth in simulation and 21.1% in fabrication. Consequently, the serial‐multi‐fed circular patch with unique angular and phase arrangements is suitable for many applications as the antenna arrays. © 2014 Wiley Periodicals, Inc. Int J RF and Microwave CAE 24:529–535, 2014.     

Fast simulation‐driven optimization of planar microstrip antenna arrays using surrogate superposition models

A technique for simulation‐driven design of excitation tapers for planar antenna arrays is presented. Our methodology exploits antenna array models constructed as a superposition of simulated radiation and reflection responses of the array under design, with only one radiator active at a time. Low computational costs of these models are ensured by using iteratively corrected electromagnetic‐simulation data computed with coarse meshes. Our technique allows for simultaneous control of the radiation pattern and the reflection coefficients of the array. Numerical efficiency as well as scalability of the technique is demonstrated using the design examples of various sizes and topologies, including a sixteen element and hundred element microstrip patch antenna arrays of the Cartesian lattice and a hundred element microstrip antenna array of the hexagonal lattice. The proposed technique is versatile as it also can be applied for simulation‐based optimization of antenna arrays comprising other types of individually fed elements, e.g., wires, strips, or dielectric resonator antennas. © 2014 Wiley Periodicals, Inc. Int J RF and Microwave CAE 25:371–381, 2015.     

Design of a novel monopulse antenna system using the time‐modulated antenna arrays

A novel monopulse antenna for a tracking radar system is proposed using the time modulated antenna array technique. The time modulation technique applied in the antenna arrays overcomes the usual need for compromise between sum and difference beams and avoids the need for implementation of two separate feed networks. The time modulated antenna array also relaxes the error tolerance of the tracking accuracy from the amplitude and phase errors, due to the new design freedom of “time” which can be controlled precisely and quickly. Moreover, the position of the target can be recovered by two reflected echoes from one previously transmitted pulse, thus the tracking errors resulting from the excitation errors and receiver noise in conventional antenna arrays can be greatly alleviated. Numerical results show that with the aid of time modulation technique, one sum beam and two difference beams can be simultaneously obtained either for the boresight or off‐boresight target tracking. © 2010 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2010.     

A new inhomogeneous partially reflecting surface for Fabry‐Perot antenna to reduce side lobe level

In this article, an extension of the spatial filter method to study Fabry‐Perot antennas with homogeneous or inhomogeneous partially reflecting surface (PRS) of finite size is proposed. This tool was subsequently validated through the study of different Fabry‐Perot antennas, with homogeneous PRS and inhomogeneous GRadient‐INdex (GRIN) PRS that present very high side lobe level (SLL). Since they are due to structure truncation, a new inhomogeneous PRS to reduce the SLL is designed with the new analytical tool. The new inhomogeneous PRS for Fabry‐Perot antenna is characterized by simulations and measurements. Compared to the homogeneous PRS antenna, the proposed PRS allows a SLL reduction of 5 dB without decreasing the 14 dBi directivity.     

共形球面阵建模及其旁瓣控制的研究

运用球面几何知识,根据孔径及最小阵元间距约束,提出了一种基于正二十面体球面三角剖分法的球面阵建模方法。应用遗传算法,针对新模型相对主瓣较高的旁瓣电平问题,以阵元位置标识向量为个体元素,进行孔径、阵元个数、最小间隔一定的稀疏优化处理。仿真结果表明,新模型在结构上实现了阵元的近似球面对称分布,运用遗传算法有效地优化了共形球面阵的旁瓣性能。