Antenna-array pattern nulling using a differential evolution algorithm

A new method based on the differential evolution (DE) algorithm is proposed for antenna-array pattern synthesis with prescribed nulls. The array excitation amplitudes are the only controlling parameters, and the objectives are to synthesize array patterns with nulls imposed on directions of interferences while keeping the sidelobe levels (SLLs) below prescribed levels. Many factors such as the excitation dynamic range ratio, null depth level, null width, and SLLs are taken into account in the synthesis. Simulation results of several typical problems are compared with published results to illustrate the effectiveness of the proposed method. © 2003 Wiley Periodicals, Inc. Int J RF and Microwave CAE 14: 57–63, 2004.     

Bees algorithm for design of dual‐beam linear antenna arrays with digital attenuators and digital phase shifters

This article describes a method of designing a reconfigurable dual‐beam linear antenna array using bees algorithm (BA). The BA is an optimization algorithm inspired by the behavior of the honey bees to find the optimal way of harvesting food resources around the hive. The proposed method is very simple and can be used directly in practice to synthesize multiple beam antenna arrays with digital attenuators and digital phase shifters. A good agreement between the desired pattern and the synthesized pattern using BA is obtained. © 2008 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2008.     

宽带雷达信号的低杂散采样系统研究

为了实现宽带雷达系统中雷达信 号的低失真采集与处理,研究并设计了具有幅相误差校正功能的宽带低杂散采样系统。该系统采用宽带模数转换（Analog to digital converter, ADC）器件和高性能可编程逻辑阵列（Field programmable gate array, FPGA）的实现方案,并从低抖动采样时钟、低噪声电源和防串扰等方面进行了低杂散最优方案研究。为了改善系统的带内传输特性,利用优化算 法设计了有限长冲激响（Finite impulse response,FIR）数字校准滤波器。最后对设计 的系统进行实验测试,结果表明系统瞬时带宽达到800 MHz以上,采样率1.8GS/s,量化位数8位、杂散电平-50 dBc,性能指标满足系统在宽带雷达信号获取、宽带雷达目标成像和宽带雷达目标回波重构等领域的应用。     

Pattern synthesis of the multimode orbital angular momentum beams based on the fruit fly optimization algorithm

The multimode orbital angular momentum (OAM) radio waves can be used to multiplex multiple transmission channels to increase the capacity of communication system without adding additional bandwidth. However, the divergence of the OAM beams and beam inconsistency escalate by increasing OAM mode number. Moreover, the worse sidelobe level (SLL) always appears along with a better convergent beam. In this article, the fruit fly optimization algorithm (FOA) is proposed to suppress the SLL in multimode OAM scenario. Based on the concentric circular array antenna (CCAA), the feeding amplitudes and the radii of the array are synthesized simultaneously to realize less than ?30 dB SLL of the multimode OAM patterns. When the main lobes with different OAM modes steered to a uniform azimuth of θ = 0° , the SLLs of these OAM modes are also suppressed to less than ?21 dB. The advantages of FOA used in the OAM pattern synthesis are verified by comparing it with the genetic algorithm (GA). The FOA‐based synthesis has a simpler implementation flow diagram which reduces the time of synthesis to 39.5% of GA.     

Spoof surface plasmon polariton‐fed circularly polarized leaky‐wave antenna with suppressed side‐lobe levels

A wide‐angle scanning circularly polarized (CP) leaky‐wave antenna (LWA) with suppressed side‐lobe levels (SLLs) is proposed, which can be a good candidate for future radar and wireless communication systems. The LWA consists of 12 cross slotted elliptical patch elements, which are fed by a microstrip spoof surface plasmon polariton (SSPP) line. Two fundamental modes of the patch array with two orthogonal polarizations can be excited by the electromagnetic coupling between the array and the SSPP line. By optimizing the elliptical eccentricity e and etching cross slots on the elliptical patch array, a 90° phase difference is introduced, and then, the CP radiation is realized. A tapered aperture field distribution is also realized by adjusting coupling intensities between the patch elements and the SSPP line, which is beneficial to reduce the SLLs. The electrical size of the LWA is 1.29λ₀ × 6.02λ₀ × 0.08λ₀, where λ₀ is air wavelength at 12.9 GHz (broadside direction). Both the simulated and measured results indicate that the CP operating band is 12.0 to 15.0 GHz. The proposed CP LWA scans continuously from ?14° to 38°. In the whole operating band, the axial ratios are less than 3 dB, and the SLLs are less than ?20 dB as well.     

Beam pointing errors of phased arrays for digital switched beam acoustic radars

Phased array antennas and corresponding driving electronics units have been introduced in Atmospheric Acoustic probing. Using modern microprocessor systems in conjunction with suitable digital electronics, it is possible to implement an acoustic probing system, with full beam switching capabilities.

The radiation pattern of a planar M × N phased array acoustic radar equipped with digital phase shifting circuits for the beam switching, is examined and all the necessary formulas are presented. For a given accuracy of phase quantization, the set of beam pointing directions which can be achieved without deterioration, due to this quantization, is computed and diagrams showing the mapping of the available beam pointing directions throughout space are presented. The relation between the cardinal number of this set of directions and the accuracy of the phase quantization is also presented.

The beam pointing errors, due to the accuracy of the phase quantization and the dissimilarities among the array's elements are analysed using simulation techniques     

一种基于微粒群算法修正相控阵相位量化误差的方法

针对相控阵天线波束指向受数字移相器量化相位影响而偏离预定指向的问题,从理论上研究了微粒群算法的应用模型,根据随机馈相的基本原理,修正了算法中微粒位置和速度因子的活动范围,计算机仿真的结果验证了该方法可行性和有效性。     

An optimal circular antenna array design considering mutual coupling using heuristic approaches

This article shows the design of a non‐uniformly excited single ring circular antenna array (CAA) for the synthesis of optimal far‐field radiation characteristics. A recently proposed meta‐heuristic based optimization algorithm called gray wolf optimization (GWO) and state‐of‐the‐art swarm intelligence based evolutionary optimization technique known as particle swarm optimization with a distribution based update mechanism (PSOd) are individually applied to determine the optimum set of current excitation amplitude weights and the inter‐element spacing among the array elements to reduce the side lobe level and 3‐dB beamwidth considering the mutual coupling. The results obtained by employing PSOd and GWO are compared to those of the uniform radiation pattern and the recently published results of state‐of‐the‐art literature having equal sets of elements to show the superiority of employed approaches. Three different design examples of 8, 10, and 12 elements CAA are reported in this article to study the performances of PSOd and GWO algorithm‐based results over the results of other recently reported literature.     

Amplitude‐only pattern nulling of linear antenna arrays with the use of an immune algorithm

This article presents an optimization immune algorithm (opt‐IA) for null steering of linear antenna arrays by controlling only the element amplitudes. Nulling of the pattern is also achieved by controlling the phase‐only and the complex weights (both the amplitude and phase) of the array elements. The opt‐IA is a new evolutionary computing algorithm based on the clonal selection principle of immune system. To show the accuracy and flexibility of the proposed opt‐IA, several examples of Chebyshev array pattern with the imposed single, multiple, and broad nulls are given. It is found that the nulling technique based on opt‐IA is capable of steering the array nulls precisely to the undesired interference directions. © 2008 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2008.     

Image vector quantization algorithm via honey bee mating optimization

The vector quantization (VQ) was a powerful technique in the applications of digital image compression. The traditionally widely used method such as the Linde–Buzo–Gray (LBG) algorithm always generated local optimal codebook. Recently, particle swarm optimization (PSO) is adapted to obtain the near-global optimal codebook of vector quantization. An alternative method, called the quantum particle swarm optimization (QPSO) had been developed to improve the results of original PSO algorithm. In this paper, we applied a new swarm algorithm, honey bee mating optimization, to construct the codebook of vector quantization. The results were compared with the other three methods that are LBG, PSO–LBG and QPSO–LBG algorithms. Experimental results showed that the proposed HBMO–LBG algorithm is more reliable and the reconstructed images get higher quality than those generated from the other three methods.     

An extended particle swarm optimization algorithm for pattern synthesis of conformal phased arrays

In this article, an extended particle swarm optimization (EPSO) algorithm is proposed for designing conformal phased arrays. On the basis of traditional particle swarm optimization (PSO), novel velocity updating mechanism, new exceeding boundary control operator, and global best perturbation are introduced in EPSO to overcome the drawbacks of PSO. To validate the efficiency of the proposed algorithm, both the classical test functions and the scenarios concerning a 1 × 9‐element cylindrical conformal phased array and a 3 × 9(27)‐element cylindrical conformal array with flat‐top shaped‐beam pattern are presented. Simulation results show that the proposed method is superior to genetic algorithm (GA) and PSO when applied to both the classical test functions and the practical problems of conformal antenna array synthesis. © 2010 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2010.     

MFOA‐integrated modified inverted F‐based adaptive array Antenna for 2.4 GHz band applications

This research has proposed a modified fruit fly optimization algorithm (MFOA)‐integrated adaptive array antenna (AAA) for the 2.4–2.5 GHz WLAN system. The principal components of the array antenna system encompass four array elements, four band pass filters (BPF), four digital phase shifters, a four‐way power combiner/splitter, a directional coupler, a radio frequency (RF) detector, and a microcontroller unit (MCU). In the realization of the adaptive antenna system, the modified inverted F antenna with a finite ground plane was first innovated and subsequently deployed as the element of the four‐element array antenna. In the study, simulations and experiments were carried out with the four‐element AAAs of two configurations, i.e. the linear and planar array configurations. The simulation and experimental results revealed that the MFOA algorithmic scheme could determine the direction of the maximum arrival signal in an efficient and accurate manner and also was capable of manipulating the radiation pattern in the desired direction. In addition, the MFOA‐integrated four‐element AAA is of compact size (20 mm × 35 mm × 1.8 mm) and operable in the 2.31–2.55 GHz frequency band with omnidirectional radiation pattern and a gain of 1.6 dBi. © 2016 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2016.     

Sequential phase feeding algorithm with minimal beam pointing error for centrosymmetric planar array antenna

Phased array antennas using digital phase shifters for beam steering are characterized by beam pointing error. This study proposes a sequential phase feeding algorithm (SPFA) with minimal beam pointing error for a centrosymmetric planar array antenna. The theoretical expression of a beam pointing error caused by phase quantification error is derived. On the basis of the derivation results, the phase shift of each element is sequentially quantified through truncating or carrying to achieve a smaller beam pointing error. The proposed algorithm improves the beam pointing accuracy of the centrosymmetric planar array antenna, and the computational load is acceptable. Simulation results verify the effectiveness of SPFA.     

Design of multiobjective reconfigurable antenna array with discrete phase shifters using multiobjective differential evolution based on decomposition

The reconfigurable design problem is to find the element that will result in a sector pattern main beam with side lobes. The same excitation amplitudes applied to the array with zero phase should be in a high directivity, low‐side lobe pencil‐shaped main beam. This work presents a multiobjective approach to solve this problem. We consider two design objectives: the minimum value for the dual beam and the dynamic range ratio in qualify the entire array radiation pattern in order to achieve the optimal value between the antenna‐array elements. We use a recently developed and very competitive multiobjective evolutionary algorithm, called MOEA/D. This algorithm uses a decomposition approach to convert the problem of approximation of the Pareto Front into a number of single objective optimization problems. We illustrate that the best solutions obtained by the MOEA/D can outperform stat‐of‐art single objective algorithm: generalized generation‐gap model genetic algorithm (G3‐GA) and differential evolution algorithm (DE). In addition, we compare the results obtained by MOEA/D with those obtained by one of the most widely multiobjective algorithm called NSGA‐II and mutliobjective DE. © 2012 Wiley Periodicals, Inc. Int J RF and Microwave CAE 22: 675–681, 2012.     

Seeker optimization algorithm for interference suppression of linear antenna arrays by controlling position‐only,phase‐only,and amplitude‐only

In this article, a stochastic search technique based on seeker optimization algorithm (SOA) is proposed for null steering of linear antenna arrays by controlling the position‐only, phase‐only, and amplitude‐only. The SOA is relatively new optimization algorithm based on the concept of simulating the act of humans' intelligent search with their memory, experience, and uncertainty reasoning. Several numerical examples of Chebyshev pattern with the single, multiple, and broad nulls imposed at the directions of interference are given to illustrate the performance and flexibility of the proposed algorithm. For a comparison, the nulling patterns obtained by simulated annealing (SA) and tabu search (TS) algorithms are also given. Furthermore, the results of SOA are statistically compared with those of SA and TS algorithms. The statistical results of simulations show that SOA is superior to the other compared algorithms. © 2011 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2011.     

A novel hybrid invasive weed optimization algorithm for pattern synthesis of array antennas

By introducing novel strategies in Invasive Weed Optimization (IWO), a hybrid algorithm called IWO‐simplified quadratic approximation (SQA) is proposed, in which an adaptive standard deviation is designed to improve the convergence performances of the original IWO, and SQA is embedded into IWO as a local search operator to enhance the overall search capability of the algorithm. Simulated results for six benchmark functions show that the proposed algorithm performs better than the original IWO algorithm. In addition, the proposed algorithm is used to the pattern synthesis of array antennas. Compared to the genetic algorithm (GA) and particle swarm optimization (PSO), the advantages of IWO‐SQA algorithm are shown. As another application, the phase‐only pattern reconfigurable arrays are synthesized by IWO‐SQA algorithm, and the numerical results show that IWO‐SQA algorithm is superior to GA. All the testing results show that it is an effective improvement to embed SQA into IWO algorithm. © 2014 Wiley Periodicals, Inc. Int J RF and Microwave CAE 25:154–163, 2015.     

基于MOPSO与凸优化算法的稀布圆阵列方向图优化

为了降低稀布阵列的峰值旁瓣电平并抑制稀布阵列的栅瓣,提出了一种多目标粒子群与凸优化相结合的方向图综合算法。该算法将多目标粒子群优化(Multi-objective particles swarm optimization,MOPSO)作为全局搜索器,凸优化算法作为局部搜索器来搜索最优解,优化的变量不仅是阵元的权值,而且还加入了阵元位置这一参数,从而能够提供更多的自由度来控制稀布阵列的性能。基于30阵元的稀布圆形阵列的仿真结果表明：与单纯使用MOPSO算法相比,本文提出的用MOPSO算法优化阵元位置,凸优化算法优化阵元权值的联合优化算法,得到的栅瓣和峰值旁瓣电平都小于-19.3　dB。     

Near field pattern uniformity for high resolution magnetic resonance imaging systems based on metaheuristic optimization

This document studies the problem of near‐field pattern uniformity in high resolution magnetic resonance imaging (MRI) systems. The existence of such inhomogeneity is related to the composition of the global near field radiation pattern of the receiving antennas in the MRI system. For the MRI image uniformity enhancement, two approaches are proposed in order to obtain the optimal image in terms of the acquisition process and subsequent post‐processing. The first one is based on a progressive variation of the antenna phase feeding in the array distribution, either at each arraying or between rings, which lets reduce the radial inhomogeneity between the central value (maximum) and the rest of the surrounding values. The second one is based on a progressive variation (rotation) of the antenna location in the array distribution, which lets reduce the pattern ripples at the outer cylindrical rings of the volume under test. In this work, a metaheuristic optimization strategy has been selected to obtain the optimal configuration. This optimal configuration implies angular rotation and the addition of feeding phase values to strain ripple reduction and pattern uniformity, depending on the particular size of the cylinder volume that conforms the volume under exploration for image acquisition.     

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.

     

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.