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In this paper, the optimal reduction of side lobe level with constraints of a suitable first null beam width of a non-uniform concentric elliptical array antenna of uniformly excited isotropic elem...

This paper presents a method based on the Moth Flame optimization evolutionary algorithm for the synthesis of Flat-top/pencil beam pair of dual beam reconfigurable concentric circular antenna array...

A compact CPW-fed slot antenna is proposed here. The antenna has a pentagonal patch nested within an asymmetrical slot along with a coplanar waveguide feed. The suggested antenna also has a circula...

This article deals with the synthesis of uniformly spaced elliptical array antenna using multi-verse optimization algorithm. Two cases are performed here. In case 1 a uniform elliptical array antenna is optimized to obtain a flat top beam pattern with 20 numbers of array elements and a specific semimajor axis value. In case 2, a 40 element elliptical array is designed with optimized semi-major axis. For both the cases the current excitation amplitude is varied within a specific boundary value to get the flat top shape in the radiation pattern. Case 1 mainly focuses on minimizing the ripple in the main beam and case 2 focuses on reducing the side lobes. The challenge of this study is to produce a flat-top pattern with a negligible amount of ripple in the main beam and lower side lobes which can essentially be applied with benefit of constant intensity over a given cross-section. The study shows the robustness of the algorithm and the usefulness of the considered optimization technique.

This study shows the performance analysis of a uniformly excited thinned elliptical array antenna of isotropic antennas using the Teaching Learning Based Optimization (TLBO) algorithm. Here objective is to reduce the side lobe level (SLL) value for a specific thinning percentage. A 40 element elliptical antenna array has been considered and two cases of thinning are performed by targeting different thinning percentages. It is to be noted that with increasing thinning percentage, the value of SLL decreases. The obtained value of the SLL after thinning is better than the SLL of a fully populated antenna array. The proposed approach is simple, economical and practically designable.

This communication is about new application of a well-known metaheuristic algorithm called Teaching–learning-based optimization towards a concentric circular array antenna for achieving minimized sidelobe levels. The problem under consideration is constrained with inter-ring radii and number of antenna array elements. Elements of the array are isotropic in nature and uniformly excited. Various array antenna parameters like best cost, mean value, standard deviation and computation time are noted in order to summarize the overall antenna performance. The effectiveness of the proposed technique is demonstrated with the help of comparing its result with some benchmarks. Optimizing the number of array elements yields best result with sidelobe levels of nearly −34.5 dB considering 9 concentric circles with common centre as example. Simulations are done using MATLAB with Intel i5 processor.

In this paper, a novel approach to synthesize sum and difference pattern through time modulation in unequally spaced linear arrays with uniform amplitude excitation is presented. Both the patterns are obtained with same element position, whereas the two patterns differ only in switch on-time sequence of the fast electronically controlled switches commutating the radiators. Stochastically, the global exploring capability of differential evolution (DE) is employed to obtain the optimized element position and on-time sequence of the antenna elements. The suitability and usefulness of the proposed method are illustrated through representative results of a 20 element linear array.

Researchers on antenna arrays usually neglect the effect of mutual coupling of antennas placed in proximity to each other. The interchange of electromagnetic energy happening between an antenna and a far field point depends not only on the transmitting antenna, but also from its neighbouring antennas. This effect is referred to as mutual coupling between dipole antenna elements and it is considered here in the synthesis of phase only reconfigurable antenna arrays. The main objective of this work is to produce desired Side Lobe Level and Voltage Standing Wave Ratio in addition to few other radiation pattern parameters. Multiverse Optimization algorithm is employed for the purpose of generating voltage amplitude and discrete phase distributions in the dipole elements for the generation of flat-top beam/pencil beam patterns. These two patterns share the common amplitude distributions and differ in phase distributions. Results obtained using MATLAB simulations prove that this algorithm accomplished its task successfully and is also found to be superior over other algorithms like Particle Swarm Optimization, Grey Wolf Optimization and Imperialist Competitive Optimization algorithms.

This paper deals with the synthesis of flattop and cosecant squared beam patterns using the firefly algorithm which is based on metaheuristics. This synthesis is followed by the correction of the radiation patterns when unfortunate malfunctioning of the individual elements in the array occurs. The necessary attention is given to the recovery process, with due emphasis on reduction of side lobe level, ripple and the reflection coefficient. Simulation in Matlab shows a successful employment of the firefly algorithm in producing voltage excitations of the good elements necessary for the recovered patterns. The performance of the firefly algorithm in failure correction is validated by duly comparing it with a standard benchmark.

This paper presents a comparative analysis of three evolutionary algorithms, namely, Backtracking Search Algorithm, Cuckoo Search Algorithm and Artificial Bee Colony Algorithms for synthesis of a scanned linear array of uniformly spaced parallel half wavelength dipole antennas. Here, antenna parameters, namely Side Lobe Level, reflection coefficient and wide null depth are taken into consideration for comparison between algorithms. In addition to it, statistical parameters, namely best fitness value, mean and standard deviation of the fitness values obtained from algorithms are compared. Mutual coupling that exists among the antenna elements is included in obtaining radiation patterns and the self-impedances along with the mutual impedances are calculated by induced Electro-Motive Force method. Two different examples are shown in this paper to validate the effectiveness of the utilized approach. Although, this approach is applied to a linear array of dipole antennas; this can be utilized for other array geometries as well.

The authors in this paper present comparative study of three evolutionary algorithms such as quantum particle swarm optimization, backtracking search algorithm and cuckoo search algorithm for design of linear array of dipole antennas that will generate far-field radiation pattern in the horizontal plane with fixed value of peak side lobe level, voltage standing wave ratio and wide null depth. The performances of the above algorithms are judged here in terms of different antenna parameters like peak side lobe level, wide null depth and VSWR as well as statistical parameters such as best fitness value, mean and standard deviation. Mutual coupling between parallel dipole antennas has also been considered. Assuming the current distribution on each thin dipole to be sinusoidal, self and mutual impedances are calculated by induced EMF method. One example is presented to show the effectiveness of the proposed approach.

Thinning a large concentric ring array by an evolutionary algorithm needs to handle a large amount of variables. The computational time to find out the optimum elements set increases with the increase of array size. Moreover, thinning significantly reduces the directivity of the array. In this paper, the authors propose a pattern synthesis method to reduce the peak sidelobe level (peak SLL) while keeping first null beamwidth (FNBW) of the array fixed by thinning the outermost rings of the array based on Gravitational Search Algorithm (GSA). Two different cases have been studied. In the first case only the outermost ring of the array is thinned and in the second case the two outermost rings are thinned. The FNBW of the optimized array is kept equal to or less than that of a fully populated, uniformly excited and 0.5 λ spaced concentric ring array of same number of elements and rings. The directivity of the optimized array for the above two cases are compared with an array optimized by thinning all the rings, while keeping the design criteria same as the above two cases. The optimized array by thinning the outermost rings gives higher directivity over the optimized array by thinning all the rings. Time required for computing the optimum elements state for the above two cases using GSA are shown lesser compared to the optimized array by thinning all the rings using the same algorithm. The peak SLL and the FNBW of the optimized array for the above two cases are also compared with the optimized array by thinning all the rings.

In this paper, the authors have proposed a method based on Quantum Particle Swarm Optimization (QPSO) algorithm in the context of radiation pattern correction of a linear array of isotropic antennas corrupted with one or more faulty antenna elements. Care is taken to maintain the values of side lobe level and maximum Wide Null Placement of the corrected pattern to be identical to the values of non-defective radiation pattern. This correction is made possible by altering the beam weights of the remaining elements in the array. The advantage of this method is that the necessity of replacement of the faulty elements is eliminated. Simulation is done on the linear antenna array constructed of individual isotropic elements separated by identical inter-element spacing and the results obtained from the simulation depict the effectiveness of the proposed method. This method can also be extended to other array geometries.

A binary firefly algorithm inspired by the behavior of artificial fireflies has been applied to thin a planar concentric ring array antenna to minimize the peak sidelobe level in a number of predefined i¾?-planes. Two different cases comprising two different design specifications for the optimized thinned array have been considered. In the first case, the array is thinned to reduce the peak sidelobe level while keeping the first null beamwidth and half power beamwidth of the array below their specified values in all the defined i¾?-planes. In the second case, peak sidelobe level of the array is reduced regardless of any pre-specified values of first null beamwidth and half power beamwidth. To illustrate the superiority of binary firefly algorithm, the thinning of the array for the two different cases has been compared with binary particle swarm optimization algorithm. Results clearly show the superiority of binary firefly algorithm in finding optimum solutions for both cases. Copyright © 2014 John Wiley & Sons, Ltd.

An optimization approach based on differential evolution (DE) is proposed to design multiple-pattern time-modulated linear antenna arrays (TMLAAs) with phase-only control by using 5-bit digital phase shifters. The synthesized multiple patterns include a pencil beam (PB), a flat-topped beam (FTB), and a cosec squared pattern (CSP). The function of the DE is to find, simultaneously, a common, i.e., fixed, set of continuous values of switch-on time durations and discrete static excitation amplitudes for 5-bit digital attenuators, and different sets of discrete excitation phase distributions for 5-bit digital phase shifters; to generate different power patterns in the far field of the TMLAA. By perturbing the static amplitude distribution of a 20-element TMLAA in the discrete search range of “(0.2–1),” the patterns are obtained by reducing side lobe levels (SLLs) to almost −20 dB and sideband levels (SBLs) to less than −25 dB. Towards the end, the same on-time and amplitude distribution is used to produce a symmetric side lobe (S-SL) and asymmetric side lobe (A-SL) CSP, and their usefulness under a noisy signal environment is discussed.

The influence of evolutionary algorithms enhanced its scope of getting its existence in almost every complex optimization problems. In this paper, cuckoo search algorithm, an algorithm based on the brood parasite behavior along with Levy weights has been proposed for the radiation pattern correction of a linear array of isotropic antennas with uniform spacing when failed with more than one antenna element. Even though deterioration produced by the failure of antenna elements results in various undesirable effects, consideration in this paper is given to the correction of side lobe level and null placement at two places. Various articles in the past have already shown that the idea to correct the radiation pattern is to alter the amplitude weights of the remaining unfailed elements, instead of replacing the faulty elements. This approach is made use of modifying the current excitations of unfailed elements using cuckoo search algorithm such that the resulting radiation pattern is similar to the unfailed original pattern in terms of side lobe level and null placement at two places. Examples shown in this paper demonstrate the effectiveness of this algorithm in achieving the desired objectives.

In time-modulated antenna arrays (TMAAs), as a result of periodical switch-on and switch- ofi of the antenna elements, including operating frequency (termed as center frequency) signal, sideband signals are appeared at either sides of the center frequency in integer multiples of the modulation frequency. In this paper, it is shown that without using phase shifters, just by suitably controlling the on-time instants (OTIs) and on-time durations (OTDs) of a time-modulated linear antenna array (TMLAA) elements, simultaneously, along with a pencil beam pattern at the operating frequency, a shaped beam pattern can be obtained at both the flrst positive and negative harmonics of the time- modulation frequency. The important advantage of such a technique is that realization of multi-beam pattern in conventional antenna array (CAA) system generally requires complex feed network, whereas by using simple radio frequency (RF) switching circuit in the feed network of TMLAA, by virtue of the properties of harmonic radiations, synthesis of a shaped pattern at either (positive or negative) harmonic results in generating the same pattern in its opposite harmonic, and the synthesized patterns at difierent harmonics can be simultaneously used as independent communication channels. By employing a difierential evolution (DE) based optimization method, numerical results for a 16-element TMLAA with uniform excitation show that in conjunction with a pencil beam pattern at the center frequency, a ∞at-top or a cosec square pattern at flrst positive and negative sidebands of side-lobe levels (SLL) i20dB can be synthesized by suppressing the higher sideband level (SBL) to below i10dB.

A method based on Fast Fourier Transform for detecting the position and the level of fault in antenna arrays, from the degraded far field pattern samples is proposed. The paper considers Chebyshev array of specified side lobe level as a desired antenna pattern and authors develop strategy to test on it. The paper also deals with several different combinations of failures and successfully detects using the proposed technique, which takes lesser computational time than other optimization algorithms. In this paper, the method is developed and applied to a linear array of isotropic antennas; however, the principle can easily be extended to other type of arrays. 

Reconfigurable antenna arrays are often capable of radiating multiple patterns by altering the excitation phases of the array elements. In this paper, an efficient method based on FFT is presented for generating dual-radiation pattern from a single rectangular planar array by modifying the excitation phases of the array elements while sharing common amplitudes. The common amplitudes shared by both the patterns and the phases which play the role of turning between the two patterns when updated over zero phase among the elements are computed using Self-adaptive Differential Evolution (SaDE) algorithm. Two different beam-pairs of pencil/pencil and pencil/flat-top are generated from the proposed array while maintaining precise design specifications. The proposed method greatly reduces the computational time as compared with the conventional method for calculating beam patterns. The dynamic range ratio of the excitation amplitudes are kept below a threshold level to reduce the design complexity of the attenuators at the feed network level and to minimize the effect of mutual coupling among the array elements. To illustrate the effectiveness of SaDE, the fitness functions associated with the two beam-pairs are minimized individually using differential evolution (DE) algorithm and particle swarm optimization (PSO) algorithm. Results clearly show the superiority of SaDE over DE and PSO to handle the proposed problem.

In this paper, a novel optimization method based on single objective, that is, minimization of sideband radiation (SBR) of ultra-low side lobe, narrow beam patterns in time modulated antenna arrays (TMAAs) is proposed. The proposed method utilizes the weighting vectors of the low side lobe Dolph-Chebyshev/Taylor series patterns as the dynamic excitation coefficients of the desired pattern at fundamental radiation. Differential evolution algorithm is employed to distribute the static amplitudes and switch-on time durations in such a way that in the optimization process, dynamic excitation distribution remains the same. Static amplitudes are perturbed in a predefined search range of (0.25, 1), whereas the weighted values of switch-on time durations are obtained by dividing dynamic excitation coefficients by static amplitudes. The technique greatly simplifies the difficulties of multi-objective TMAA synthesizing problem by reducing it to a single-objective optimization problem. Numerical examples for a 32-el...

In this paper, a new technique is proposed to optimize the con∞icting parameters like low value of maximum side lobe level (SLL), narrow beam-width of the main beam and low value of maximum sideband radiation level (SRL) of time-modulated linear antenna arrays (TMLAAs). The method is based on minimizing a multi-objective fltness function by using single-objective difierential evolution algorithm (DEA) technique. The method is applied to both uniformly excited TMLAA (UE-TMLAA) and non-uniformly excited TMLAA (NUE-TMLAA) to synthesize low side lobe optimum pattern at operating frequency by suppressing the sideband radiation level to a su-ciently low value. For UE-TMLAA only the switch- on time durations of the array elements and for NUE-TMLAA the switch-on time durations and the static amplitudes with predetermined dynamic range ratio (DRR) of static amplitudes are taken as the optimization parameters for the DEA. To show efiectiveness of the proposed approach, the single-objective DEA optimized results are compared with those obtained by other single objective and multi- objective techniques that has been reported previously. Also, flrst null beam width (FNBW) and half power beam width (HPBW) of the DEA optimized patterns at fundamental radiation are compared with those of the Dolph-Chebyshev (D-C) pattern of same SLL.

A novel approach using Differential Evolution (DE) is proposed for linear array failure correction. In presence of the failure of array elements, only the inter-element spacing's between the array elements are adjusted to regain the pattern closed to the original one. The proposed approach is a cost effective method as no additional attenuators or phase shifters are required. A fitness function has been defined suitably and DE algorithm, coded in MATLAB is employed to minimize the cost function using inter-element spacing as optimization parameter vector. Considering a 30 element linear array, the numerical results for the three cases with failure of one. two and three elements are presented and the MATLAB simulated optimized result is validated in FEKO to prove the effectiveness of the proposed entail approach.

The radiation pattern of a small-size concentric ring array antenna does not remain φ-symmetric, if the array is made with an appreciably lesser number of antenna elements. The sidelobe level, first null beamwidth (FNBW), half-power beamwidth (HPBW), and the null depths of the radiation pattern change significantly in different φ planes. An efficient pattern synthesis method has been developed in this work to reduce the variation of sidelobe level, FNBW, and HPBW of a small-size concentric ring array of isotropic antennas, for different φ cuts. It is done by finding out an optimum set of amplitude distribution of the array elements using firefly algorithm. The sidelobe level and the first null depth of the array are kept below a desired value for all the defined φ cuts. The directivity of the optimized array and the uniform array has been computed. The variation of all these parameters for different φ cuts has been compared to the same array with uniform excitation among the elements.

Reduction of side lobe levels in a concentric ring arrays results in wide first null beamwidth. The authors propose a pattern synthesis method based on the Differential Evolution (DE) algorithm to reduce the side lobe levels of a concentric ring array of isotropic antennas while keeping the first null beamwidth (FNBW) fixed and variable by radial variation of amplitudes of the array elements. Two different cases have been studied, one with fixed initial interelement distance and another with optimum interelement distance for the entire array. The FNBW of the optimized array is kept equal to or less than that of a uniformly excited and 0.5 λ spaced concentric ring array of the same number of elements and rings. Results are also compared with Genetic Algorithm to establish its superiority.

Reconflgurable antenna arrays are often capable of radiating multiple patterns by modifying the excitation phases of the elements. In this paper a method based on Fire∞y Algorithm (FA) has been proposed to obtain dual radiation pattern from a concentric ring array of isotropic elements, by flnding out two difierent combinations of states for the switches, which are assumed to be connected with the rings of the array, along with optimum set of 4-bit radial amplitude and 5-bit radial phase distributions of the array elements for the speciflc switch combinations. The optimum excitations of the array elements in terms of discrete amplitudes and discrete phase, and the difierent switch combinations for the speciflc excitations are computed using Fire∞y Algorithm. To illustrate the efiectiveness of Fire∞y Algorithm, the two beam pairs have been computed by the same procedure from the same array, using Particle Swarm Optimization (PSO) algorithm, without changing their design criteria. Results clearly show the superiority of the Fire∞y Algorithm over Particle Swarm Optimization to handle the proposed problem.

This paper presents a method based on iterative fast fourier technique for placing nulls in prescribed directions by amplitude-only control method in the radiation pattern of scanned linear array of uniformly spaced isotropic antennas with fixed dynamic range ratio of amplitude distribution and minimum peak side lobe level. Two examples have been presented, one with 20 isotropic antennas for placing two nulls and another with 22 isotropic antennas for placing wide null. Dynamic range ratio in both the cases has been fixed at 4.0.The method uses the property that for a linear array with uniform element spacing, an inverse Fourier transform relationship exists between the array factor and the element excitations.

This paper describes the application of two recently developed metaheuristic algorithms known as flre ∞y algorithm (FFA) and artiflcial bees colony (ABC) optimization for the design of linear array of isotropic sources. We present two examples: one for broad side arrays and the other for steerable linear arrays. Three instances are presented under each category consisting of difierent numbers of array elements and array pattern directions. The main objective of the work is to compute the radiation pattern with minimum side lobe level (SLL) for specifled half power beam width (HPBW) and flrst null beam width (FNBW). HPBW and FNBW of a uniformly excited antenna array with similar size and main beam directions are chosen as the beam width constraints in each case. Algorithms are applied to determine the non-uniform excitation applied to each element. The efiectiveness of the proposed algorithms for optimization of antenna problems is examined by all six sets of antenna conflgurations. Simulation results obtained in each case using both the algorithms are compared in a statistically signiflcant way. Obtained results using flre ∞y algorithm shows better performances than that of artiflcial bees colony optimization technique provided that the same number of function evaluations has been considered for both the algorithms.

Scanning a planar array in the x-z plane directs the beam peak to any direction ofi the broadside along the same plane. Reduction of sidelobe level in concentric ring array of isotropic antennas scanned in the x-z plane result in a wide flrst null beamwidth (FNBW). In this paper, the authors propose pattern synthesis methods to reduce the sidelobe levels with flxed FNBW by making the scanned array thinned based on two difierent global optimization algorithms, namely Gravitational Search Algorithm (GSA) and modifled Particle Swarm Optimization (PSO) algorithm. The thinning percentage of the array is kept more than 45 percent and the flrst null beamwidth (FNBW) is kept equal to or less than that of a fully populated, uniformly excited and 0:5‚ spaced concentric circular ring array of same scanning angle and same number of elements and rings.

The authors presented two different optimization methods-one is quantum particle swarm optimization (QPSO) and another is backtracking search algorithm (BSA). Combined with inverse fast fourier transform (IFFT), the paper deals with the synthesis of array of linearly spaced and mutually coupled half wavelength very thin vertical and parallel dipoles with fixed value of voltage standing wave ratio (VSWR) and side lobe level. The performances of the two algorithms are compared in terms of different antenna parameters like side lobe level, VSWR as well as statistical parameters such as best fitness value, mean, standard deviation and computation time. There exists mutual coupling among the parallel half-wavelength dipole antennas. Self and mutual impedances are derived from induced EMF method assuming distribution of current on each dipole is sinusoidal. The pattern so generated is broadside in the horizontal plane. There exists a relationship between the IFFT and the array factor for an array of linearly and uniformly spaced isotropic antennas. Array factor is found out by applying inverse fast fourier transform on the element excitations that in turn reduces the computational time. It is assumed that the element pattern of vertical half-wavelength dipole antenna is omni-directional in the horizontal plane. One example is presented to prove the effective use of the approach proposed.

In this paper, the authors present second degree polynomial approximated phase-only synthesis of two different types of symmetric sector or flat-top beams of equally spaced linear antenna arrays of isotropic radiators with single pre-fixed cosine on a pedestal amplitude distributions using real-coded or real-valued genetic algorithm. This gives a regular shape to the phase distributions of the radiators. Regular shape phase distributions result in simpler feed network design compared to irregular shape phase distributions. A good agreement between desired and synthesized pattern using genetic algorithm (GA) is reported.

In this paper, we propose an optimization method based on real-coded genetic algorithm (GA) with elitist strategy for thinning a large linear array of uniformly excited isotropic antennas to yield the maximum relative sidelobe level (SLL) equal to or below a fixed level. The percentage of thinning is always kept equal to or above a fixed value. Two examples have been proposed and solved with different objectives and with different value of percentage of thinning that will produce nearly the same sidelobe level. Directivities of the thinned arrays are found out and simulation results of different problems are also compared with published results to illustrate the effectiveness of the proposed method.

In this paper, we present a comparison study between phase-only and amplitude-phase synthesis of symmetrical dual-pattern linear antenna arrays using floating-point or real-valued genetic algorithms (GA). Examples include a sum pattern and a sector beam pattern. In the former, phase is only optimized with predetermined Gaussian amplitude distribution of fixed dynamic range ratio (|amax/amin|) and in the latter, both are optimized with less dynamic range ratio than the former and yet share a common amplitude distribution.

In this research paper, quantum particle swarm optimization (QPSO) algorithm, an algorithm founded on the basic theory of particle cluster and properties of quantum mechanics, has been introduced for design of uniformly spaced scanned linear array antennas with definite value of sidelobe level (SLL), first null beam width (FNBW), and broad null depth. An effort is made such that these parameters are made equal to their related specific values. This is usually done by changing excitation current amplitude of the elements. The expression of array factor is derived by using the property of linear array antennas. One example has been presented with 35 isotropic antennas. Generated Pattern is scanned to an angle of 30°. The obtained results have shown that this technique is able to find required value of SLL, FNBW, and wide null depth. Although, the proposed method is developed and applied to a linear array of isotropic antennas; however, the principle can easily be applied to other types of arrays.

In this paper, sideband radiations which are generally regarded as the undesired effects of time-modulated antenna arrays (TMAAs), are exploited to design multi-beam antenna arrays. Time modulation (TM) is applied into uniformly excited linear array of half wave dipole radiators to generate low side-lobe sum and difference patterns at the center frequency and first sideband respectively while the maximum power level at the higher sidebands are suppressed significantly by optimizing the periodical on-off switching instants of the antenna elements by using fire-fly algorithm (FA). The FA optimized pattern as realized in MATLAB platform is validated by designing the uniformly excited time modulated linear array (UE-TMLA) in CST-MWS with the same on-time sequence as obtained by using FA and the patterns are compared.

Evolutionary algorithms play an important role in synthesizing linear array antenna. In this paper, the authors have compared quantum particle swarm optimization (QPSO) and backtracking search algorithms (BSA) in failure correction of linear antenna arrays constructed using half wavelength uniformly spaced dipoles. The QPSO algorithm is a combination of classical PSO and quantum mechanics principles to enhance the performance of PSO and BSA is considered as a modernized PSO using historical populations. These two algorithms are applied to obtain the voltage excitations of the nondefective elements in the failed antenna array such that the necessary objectives, namely, the minimization of parameters like side lobe level (SLL) and voltage standing wave ratio (VSWR), are achieved leading to their values matching closely the desired parameter values. The results of both algorithms are compared in terms of parameters used in the objective function along their statistical parameters. Moreover, in order to reduce the processing time, inverse fast Fourier transform (IFFT) is used to obtain the array factor. In this paper, an example is presented for the application of the above two algorithms for a linear array of 30 parallel half wavelength dipole antennas failed with 4 elements and they clearly show the effectiveness of both the QPSO and BSA algorithms in terms of optimized parameters, statistical values, and processing time.

This paper describes the design of non-uniformly excited and uniformly spaced thinned linear array antenna. The method is based on the iterative fast Fourier transform. Thinning of the antenna array can be accomplished by making the predetermined number of element excitations to zero to meet the desired side lobe level. In this paper two examples are presented for the maximization of the number of switched off elements to meet the desired side lobe level of -35 dB and -30 dB with a linear array antenna of 160 elements. The basic advantage of the iterative Fourier transform is its computational speed.

Compared to conventional antenna arrays (CAAs), a greater flexibility in designing time-modulated antenna arrays (TMAAs) is achieved by means of time as a fourth dimension. In this paper, an optimization algorithm based on differential evolution algorithm (DEA) is used to suppress both side lobe level (SLL) and side band level (SBL) of a uniformly excited time modulated linear array (UE-TMLA) of co-planer short dipoles by optimizing the on-time durations of the antenna elements. The DE optimized pattern as realized in MATLAB platform is validated by designing the UE-TMLA in CST-MWS with the same on-time sequence as obtained by using DE and the patterns are compared. The experiment is done by taking a UE-TMLA of 16 co-planer short dipoles and a DE optimized pattern with SLL of -20.4 dB is obtained by suppressing maximum SBL to -30 dB.

In this work, the effectiveness of a relatively newly developed optimization algorithm, artificial bee colony (ABC) algorithm has been employed to synthesize uniformly excited, non-uniformly spaced, symmetrical linear arrays. ABC is used to reduce the side lobe level (SLL) of uniformly excited linear antenna arrays by taking the element spacing as the optimization parameters. The effectiveness of the proposed approach is demonstrated by considering a linear antenna array of 32 elements. The array of isotropic elements is synthesized for the different search space of the element spacing and a typical variation of the SLL with different limiting values of the maximum element spacing is presented. It is observed that, for the isotropic element array when the search range of the normalized element spacing's relative to the operating wavelength is (0.5, 1), the maximum reduction of side lobe level (-21.22 dB) is obtained. At the end the array with half-wavelength dipole is considered and with the search range of the element spacing's, (0.5, 1), SLL is reduced to -22.99 dB.

In this paper, a very simple and powerful method for the synthesis of linear array antenna is proposed. This method ensures the desired level of side lobe level (SLL) along with the minimum desired value of first null beam width (FNBW). Method includes finding a set of non-uniform amplitude excitation using particle swarm optimization (PSO) and finding the appropriate value of uniform element spacing for the linear array, which qualifies the desired value of SLL and provides minimum desired FNBW value. PSO algorithm is a high-performance algorithm capable of solving general N-dimensional, linear and nonlinear optimization problems. Work in this paper includes, two-step method for getting the fixed value of SLL and minimum desired FNBW. In the first step, PSO is used for optimizing both SLL and FNBW, but the main emphasis is given for the desired SLL requirement to achieve. In the second step, SLL remains almost constant but FNBW is minimized to archive the desired value or even below the desired value of FNBW. The simulation results have shown that this technique is able to find the desired value of SLL with the very narrow FNBW.

In this paper, a cosecant squared shaped beam pattern is synthesized from a uniformly spaced but nonuniformly excited linear antenna array where the uniform spacing of the array elements is considered as half of the desired signal wavelength. The shaped beam pattern is synthesized for the angular beam width of 320 by reducing the side lobe level (SLL) to -20.06 dB and almost without any ripple in the shaped region. To get the desired pattern, excitation coefficients and the static phase shift of the array elements are taken as the optimizing parameters and the differential evolution (DE) algorithm is used as the optimizing algorithm. It is further observed that the desired array pattern is remained unaltered for a band of frequency on either side of the operating frequency.

Obtaining a wide null over a certain angular range and lower values of side lobe levels finds extensive applications in communication and radar engineering. The high side lobe level can degrade the system performance as well as antenna power efficiency significantly. In this paper, we present the iterative Fast Fourier technique to generate wide nulls while keeping the side lobe level to its minimum value. Advantage of this technique is very high computational speed. This is because of the fact that the core calculations are based on direct and inverse fast Fourier transforms (FFT). The simulation results have shown that this technique is able to find suitable weights vector to reduce the side lobe power for the given null depth.

This paper describes amplitude control method for the synthesis of broadside non-uniformly excited and uniformly spaced linear array antenna for generation of multiple side lobe levels using iterative Fast Fourier transform. Compared to other evolutionary methods this technique has higher computational speed. This is the major advantage of this technique i.e. it takes less computation time. This is because of the fact that the core calculations are based on direct and inverse fast Fourier transforms (FFT). An example has been presented with 30 isotropic antennas for producing two different side lobe levels of −50 dB and −30dB.