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This paper investigates the application of Adaptive Differential Evolution (DE) algorithm to enhance the performance of broadband antenna. A linear array consisting of half wavelength long unequally spaced parallel dipoles is designed to meet the increasing demand of extremely large bandwidth in wireless communication systems. Array is devised to maintain an almost invariable radiation patterns over a wide range of frequencies. Constant beam widths, good side lobe characteristics and minimum bearable voltage standing wave ratio (VSWR) are achieved for the allocated frequency band. Coupling effect has been taken into account via induced EMF method and minimized in terms of VSWR. In the proposed technique excitation and position of the individual array element are optimized in order to obtain a fixed SLL and minimum bearable VSWR over the proposed bandwidth. Dynamic range ratio (DRR) of excitation distribution is fixed at an optimum value for further mitigation of coupling effect. Phase distribution for all the elements is kept at zero degree. An adaption schemes to tune the scaling factor and crossover rate of population in DE is used to solve the design problem. Numerical results show the aforementioned modifications make the algorithm more effective to design the proposed broadband array.

A pattern synthesis method based on Gravitational Search Algorithm (GSA) is presented to generate a dual pencil beam patterns with two different pre-defined sidelobe levels from a concentric ring array of isotropic antennas. Both the patterns are generated by sharing a common optimum amplitude distribution of the array elements. The pattern with sidelobe level lower than the other is generated by switching phase distribution of the array elements from zero to the optimum value. The amplitude and the phase of the array elements are varied radially along the array using GSA to generate a dual pencil beam of two different sidelobe levels.

In recent years, evolutionary optimization (EO) techniques have attracted considerable attention in the design of electromagnetic systems of increasing complexity. This paper describes a method of synthesis of uniform circular array antenna using three recent search heuristics: Modified Particle Swarm Optimization (MPSO), Differential Evolution (DE) and Artificial Bee Colony (ABC) optimization algorithms. The objective of the work is to generate a pencil beam with minimum Side Lobe Level (SLL) and maximum possible directivity. Excitation of individual array elements is computed using the algorithms. Dynamic Range Ratio (DRR) of current amplitude distribution is fixed at an optimum value. Phase of excitation distribution is fixed at zero degree. Simulation results illustrate the performance of MPSO, DE and ABC regarding their applicability as numerical optimization techniques.

Reduction of sidelobe level in a concentric ring array results in wide first null beamwidth. The authors propose a pattern synthesis method based on the Differential Evolution (DE) algorithm to reduce the sidelobe level of a concentric ring array of isotropic antennas while keeping the first null beamwidth (FNBW) fixed and variable by optimizing both ring spacing and interelement distance of each ring.

This paper describes a method of synthesis of uniform circular array with optimized spacing using three recent search heuristics: Modified Particle Swarm Optimization (MPSO), Differential Evolution (DE) and Artificial Bees Colony (ABC) algorithms. The objective of the work is to generate a pencil beam with minimum Side Lobe Level (SLL) and maximum possible Directivity for fixed half power beam width (HPBW). Excitation of individual array elements is computed using the algorithms. Dynamic Range Ratio (DRR) of current amplitude distribution does not exceed a prefixed threshold value. Phase of the individual excitation is fixed at zero degree. Simulation results show considerable enhancements in array performances using the global optimizers. The paper finally illustrates a comparative evaluation of the three proposed algorithms regarding their applicability as numerical optimization techniques.

In this article, Differential Evolution (DE) algorithm has been used to design a non-uniformly spaced collinear dipole array of uniformly optimized length. The goal is to generate a pencil beam in the horizontal plane with minimum Standing Wave Ratio (SWR) and fixed Side Lobe Level (SLL). Dynamic Range Ratio (DRR) of current amplitude distribution is kept at a fixed value. A simultaneous optimization of excitation distribution and geometry of individual array elements is carried out to improve radiation characteristics. Coupling effect between the array elements is analyzed using induced EMF method and minimized in terms of SWR. DRR is fixed at a lower value in order to compensate mutual coupling between individual radiators. Phase distribution for all the elements is kept at zero degree. Numerical results show the effectiveness of the algorithm for the design of the proposed array.

This paper investigates the application of recently proposed Differential Evolution (DE) algorithm for evolutionary optimization of non-uniformly spaced collinear dipole array of any length. The array is computed to generate a pencil beam in the horizontal plane with minimum Standing Wave Ratio (SWR) and a desired Side Lobe Level (SLL). Dynamic Range Ratio (DRR) of current amplitude distribution is kept at a fixed value. A simultaneous optimization of excitation distribution and geometry of individual array elements is carried out to improve radiation characteristics. Coupling effect between the elements is analyzed using induced EMF method and minimized in terms of SWR. DRR of excitation distribution is fixed at an optimum value to obtain impedance matching condition. Phase distribution for all the elements is kept at zero degree. Numerical results show the effectiveness of DE for the design of the array.

In this paper, the authors present a method based on modified particle swarm optimization for generating pencil beam in the vertical plane with minimum side lobe level and fixed first null beamwidth. The first null beamwidth is made equal to that of a uniformly excited and uniformly spaced multiple concentric circular ring array of same number of elements and same number of rings. The excitation amplitude is radially varied and optimized to achieve the goal. Example illustrates the potential of the method.

In this paper, the authors describe the synthesis of flat-top beam power pattern for antennas composed of concentric rings of isotropic elements. The synthesis is performed by particle swarm optimization (PSO), varying amplitudes and phases of the elements radially, so as to obtain desired side lobe level and ripple of flat-top beam in the vertical plane. Example illustrates the potential of the method.

In this paper, we describe the use of real-coded genetic algorithm (GA) for design of reconfigurable dual-beam linear isotropic antenna arrays with phase-only control of discrete phase shifters. The problem is to find a fixed amplitude distribution that will generate two broadside symmetrical beams in vertical plane: a pencil beam with zero phases and a flat-top beam with discrete phases of a five-bit discrete phase shifter, with or without minimizing dynamic range ratio (amax/amin) of excitation amplitude distribution.

[Abstract] In this letter, the authors propose an optimization method based on the genetic algorithm (GA) to reconfigure a linear array of vertical half-wavelength dipole antennas to generate two patterns with minimum active impedance variation when the antenna switches from one pattern to other in the presence or absence of a ground plane behind the array. The problem is to find a fixed voltage amplitude distribution that generates two broadside symmetrical beams in the horizontal plane: a pencil beam with zero phases and a flat-top beam with phases in the range from -180deg to +180deg. Mutual coupling effect is taken into account via open circuit mutual impedance matrix

This paper presents a new technique based on optimization tools to design phase only, digitally controlled, reconfigurable antenna arrays through time modulation. In the proposed approach, the on-time durations of the time-modulated elements and the static amplitudes of the array elements are perturbed in such a way that the same on-time sequence and discrete values of static amplitudes for four bit digital attenuators produces either a pencil or a flat-top beam pattern, depending on the suitable discrete phase distributions of five bit digital phase shifters. In order to illustrate the technique, three optimization tools: differential evolution (DE), artificial bee colony (ABC), and particle swarm optimization (PSO) are employed and their performances are compared. The numerical results for a 20-element linear array are presented.

Sidelobe reduction in an array antenna results in increased first null beamwidth. In this paper, the authors present a method based on a novel particle swarm optimisation with time-varying maximum velocity for focusing a beam at any direction in the vertical plane of a concentric ring array antenna with minimum sidelobe level while keeping the first null beamwidth of the array fixed. The excitation amplitude of the array elements along with the central element are radially varied and optimised using the proposed algorithm to reach the goal. Three different cases have been presented to illustrate the potential of the method.

The paper describes the application of novel meta-heuristics of the fire fly algorithm for reduction of the maximum Side Lobe Level (SLL) with specific First Null Beam Width (FNBW) of thinned two-ring Uniform Concentric Circular Arrays (UCCA) of isotropic elements. The effect of thinning is analyzed in the four subsequent examples using uniform and non-uniform excitations for different FNBW. Optimization is carried out without and with prefixing the value of the percentage of thinning. The UCCA containing 35 and 70 elements in the two successive concentric rings is optimized using FFA. The example using non-uniform excitation is proved more efficient to reduce SLL for same FNBW. Simulation results show the SLL performance improves as we chose the FNBW wider in the designing problem. Fixing the percentage of thinning at a higher value increases the power efficiency of the feeding network with little compromise on the design specifications. The non-uniformly excited thinned concentric array is again optimized using two more state-of-the-art algorithms, namely, Particle Swarm Optimization (PSO) and Differential Evolution (DE) to compare the effectiveness of each algorithm in a statistically meaningful way. Design results using fire fly algorithm shows better performances compared to PSO and DE provided the same number of function evaluation has been considered for all the algorithms.