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In the present paper three evolutionary algorithms are compared and discussed for synthesizing a linear array of dipole antenna of half-wavelength oriented horizontally. All the dipoles are mutually coupled and designed to radiate the flat-top beam (FTB) pattern including multiple single null steering with little ripple deviation. The adopted evolutionary algorithms are; flower pollination algorithm (FPA), firefly algorithm (FA) and back tracking search algorithm (BSA), respectively. These algorithms are then combined with an efficient Inverse Fast Fourier Transform (IFFT) for reduction in the computation of evaluating time meaningfully. The required synthesis is attained by generating the current amplitudes at 00 and 1800 using binary phase shifters for the antenna array. The performance analysis of key antenna parameters along with the statistical parameters is achieved with the help of the optimization process and compared. In this paper, the MATLAB tool is used as a validation tool and the obtained simulation results are very satisfying and acceptable.

A new technique for the restoration of the field pattern in a linear array constructed using parallel dipole antennas is carried out by altering the spacing between the array elements. In an N-element optimized linear antenna array, the differential evolution (DE) algorithm is used to correct a specific number of failed elements with the objective of achieving the specified side lobe level (SLL) and maximum reflection coefficient (RC). The mutual coupling effects of the pattern are taken into consideration here. The necessary simulations are performed using Matlab software which depicts the effectiveness of this technique in establishing the corrected far field radiation pattern approaching the desired radiation pattern. To prove its effectiveness, two examples are tested in this process. The simulation findings are verified using the FEKO electromagnetic simulation software. [ABSTRACT FROM AUTHOR]

In this paper, the effect of perfect electric conductor (PEC) as a ground plane on antenna array is investigated. Vertical electric dipole which is of infinitesimal small length is considered as an array element. The effect of mutual coupling is neglected in this work. The effect of PEC as a ground plane is analyzed by considering two cases in this paper. Firstly, the array elements are kept at constant height above PEC and in second case, the array elements are kept with gradually increasing height above the ground plane. Performance of antenna array in presence of PEC for both cases is investigated in terms of main lobe beam width and side lobe level using array factor pattern. Side lobe level and beam width results are compared both in presence of PEC and without PEC i.e. array in free space. It has been observed that there is improvement in the main lobe beam width and reduction in side lobe level when the array is used with PEC as a ground plane with elements kept at gradually increasing height from the ground plane. In addition to this, overall directivity of the array is also found to be increasing exponentially with height on application of ground plane in comparison with that of antenna arrays without ground plane. [ABSTRACT FROM AUTHOR]

This paper presents novel design techniques for the Fermat spiral, considering a maximum side lobe level (SLL) reduction. The array system based on a Fermat spiral configuration considers techniques based on uniform and non-uniform amplitude excitation. The cases of uniform amplitude excitation are the golden angle and the optimization of the angular separations. The cases of non-uniform amplitude excitations consider a raised cosine distribution and the optimization of the amplitude excitations through the Fermat spiral array. In this study, the method of genetic algorithms (GA) was used in the cases to find the values of the angular separations and the amplitude excitations of the Fermat spiral array. A performance evaluation was conducted for all these design cases, considering the Fermat spiral geometry. These design cases were validated using electromagnetic simulation to take mutual coupling into account and consider the effect of the antenna element pattern in each proposed design case.

In the present paper three evolutionary algorithms are compared and discussed for synthesizing a linear array of dipole antenna of halfwavelength oriented horizontally. All the dipoles are mutually coupled and designed to radiate the flat-top beam (FTB) pattern including multiple single null steering with little ripple deviation. The adopted evolutionary algorithms are; flower pollination algorithm (FPA), firefly algorithm (FA) and back tracking search algorithm (BSA), respectively. These algorithms are then combined with an efficient Inverse Fast Fourier Transform (IFFT) for reduction in the computation of evaluating time meaningfully. The required synthesis is attained by generating the current amplitudes at 00 and 1800 using binary phase shifters for the antenna array. The performance analysis of key antenna parameters along with the statistical parameters is achieved with the help of the optimization process and compared. In this paper, the MATLAB tool is used as a validation tool and the obtained simulation results are very satisfying and acceptable. [ABSTRACT FROM AUTHOR]

Side lobe level (SLL) reduction has a great importance in recent communication systems. It is considered as one of the most important applications of digital beamforming since it reduces the effect of interference arriving outside the main lobe. This interference reduction increases the capacity of the communication systems. In this paper, the hardware implementation of an antenna array system for SLL reduction is introduced using microstrip technology. The proposed antenna array system consists of two main parts, the antenna array, and its feeding network. Power dividers play a vital role in various radio frequency and communication applications. A power divider can be utilized as a feeding network of an antenna array. For the synthesis of a radiation pattern, an unequal-split power divider is required. A new design for a four ports unequal circular sector power divider and its application to antenna array SLL reduction is introduced. The amplitude and phase of the signals emerging from each power divider branch are adjusted using stub and inset matching techniques. These matching techniques are used to adjust the branches impedances according to the desired power ratio. The design of the antenna array and the power divider are made using the software package CST MICROWAVE STUDIO. The power divider is realized on Rogers R03010 substrate with dielectric constant εr=10.2, loss tangent of 0.0035, and height h=1.28mm. In addition, a design for ultra-wide band (UWB) antenna element and array are introduced. The antenna elements and the array are realized on the FR4 (lossy) substrate with dielectric constant εr=4.5, loss tangent of 0.025, and height h=1.5mm. The fabrication is done using thin film technology and photolithographic technique. The experimental measurements are done using the vector network analyzer (VNA HP8719Es). Good agreement is found between the measurements and the simulation results.

Inspired by the biological evolution and the natural selection, evolutionary algorithms have already shown their success in obtaining the solutions for many complex optimisation problems. The aim of this paper is to study the performance of Flower Pollination algorithm for the synthesis of the flat-top beam pattern in linear antenna arrays with restrictions on the peak side lobe level, ripple in the flat-top portion, and maximum Voltage Standing Wave Ratio along with the two independent nulls. Mutual coupling is considered between the parallel dipole antennas. This synthesis is obtained by the generation of current amplitudes with binary phase shifters of 0 and 180 degrees for the antenna elements. Matlab software is used for the simulations. The values of the different antenna parameters as well as the statistical parameters such as the global best fitness value, worst fitness value, mean and standard deviation from the optimisation process generated by the simulations are obtained. Two examples are presented in this paper with different number of antenna elements. The obtained results show the superiority of the Flower Pollination algorithm over Particle Swarm Optimisation algorithm. Moreover, the results obtained from simulations are validated by using FEKO software. [ABSTRACT FROM AUTHOR]

Abstract: An accurate imposing of broad nulls in the side lobe levels of radiation pattern of the symmetric time modulated linear antenna array (STMLAA) is proposed in this article. The broad nulls are intended to be imposed in the range of the angular sector of 40° to 70° of angle of arrival in θ plane which is symmetrical to the main beam of the radiation pattern. The metaheuristic evolutionary algorithm with the hybridization of flower pollination algorithm with Nelder‐Mead simplex method called memetic flower pollination algorithm is used uniquely for the application of pattern synthesis to serve this purpose. The optimized results obtained by using memetic flower pollination algorithm are validated by using Computer Simulation Technology Microwave Studio by taking practical elements of microstrip patch antenna. From algorithm's point of view, the superiority of the adopted algorithm has been justified by the statistical analysis performed along with the basic algorithms, like real‐coded genetic algorithm, particle swarm optimization, and differential evolution. 16‐, 32‐, and 64‐element STMLAA are realized to demonstrate the proposed concept. Broad nulls are aimed to be obtained by the optimal perturbations of switching time sequences and the interelement separations of the elements having symmetricity with respect to the main beam of the radiation pattern. Moreover, the maximum side lobe level is also reduced as compared with that of the uniform linear antenna array for the same element. The microstrip patch antenna with operating frequency of 5.85 GHz has been designed, which is applicable for Wi‐Max application. The concept of pattern multiplication is applied to multiply the element pattern of patch antenna and the array factor of STMLAA of isotropic elements. [ABSTRACT FROM AUTHOR]

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.

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. [ABSTRACT FROM AUTHOR]

In this paper, firefly algorithm is utilized for the correction of radiation pattern of a linear antenna array of parallel half-wavelength dipole antennas spaced uniformly when defected completely with more than one dipole element. Mutual coupling between the antennas along has been considered along with the effect of distance between the antenna array and the ground plane on the radiation pattern. Adjustments are done in the values of the excitation voltage of the remaining nondefective elements through evolutionary algorithm such that the parameters, namely, side lobe level and maximum reflection coefficient (S11) in dB of the corrected pattern are calculated and efforts are taken to make it closer to the original pattern values. This certainly avoids replacing of defective elements. The element pattern of individual elements in the array has been assumed omnidirectional in the plane considered. Examples are shown to produce the response of the proposed approach using evolutionary algorithm for three element failures out of twenty elements in the array with the effect on various distances between the antenna array and ground plane. Even though, the method is utilized here for a linear dipole antenna array, it can be applied for other antenna array configurations also. [ABSTRACT FROM AUTHOR]

ABSTRACT A method of utilizing frequency selective surface (FSS) to reduce side lobe level (SLL) is proposed. The FSS composed of annular slot arrays loaded with resistors is divided into several regions along the electric field direction. Each region has difference transmission amplitude (TA) but the same transmission phase (TP). Through the appropriate distribution design for each region, the output wave with tapered TA and uniform TP is obtained when the FSS is illuminated by a plane wave. Thus the FSS could be utilized to reduce the antenna SLL. An H-plane sectorial horn array is adopted as an exciting source to validate its SLL reduction performance. Simulation results show that the proposed FSS superstrate makes the SLL of the horn array in the E-plane desirably suppressed from −12.4 to −25.9 dB at 10.3GHz with the gain reduced from 18.3 to 16.7 dBi. The measured results agree well with the simulated ones. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:1971-1975, 2015 [ABSTRACT FROM AUTHOR]

A $16 \times 16$ substrate-integrated waveguide (SIW) cavity-backed array antenna is proposed in this paper. The array consists of two layers. The top layer employs novel SIW-based subarrays with a compact size. The bottom layer is an 8 \times 8$ SIW corporate-feed network to feed the subarrays. The Chebyshev amplitude weighting is employed in the feed network, which substantially reduces the side lobe level (SLL). The array antenna is fabricated using low-cost printed circuit board technology. The experimental results show that the proposed array antenna has a large bandwidth of 15% from 18.5 to 21.5 GHz with a peak gain of 29.1 dBi at 20.5 GHz. Across the entire band, high radiation efficiency above 62% and a low SLL below - 17\,\mathbf{dB} are realized. The design principle can be used as a guidance for large-scale planar array antenna design and the proposed antenna can be used as a receiving antenna located on the ground in satellite communication systems. [ABSTRACT FROM PUBLISHER]

In this paper, a new modified method is presented for the synthesis of a linear antenna array to obtain a desired array pattern (shaped or pencil) with low side lobe level. Based on the original invasive weeds optimization (IWO), our modified IWO (MIWO) uses the process of mutation for the calculation of standard deviation. The shaped beam pattern is synthesized by respecting a desired cosecant pattern and supressing side lobe level to -25 dB. To achieve the desired pattern, both amplitude and phase of each element in the array are optimized when the spacing between the elements is fixed to the half wavelength. For the desired pencil beam pattern, the inter-element spacing's are controlled while maintaining uniform excitations. Selected examples, for both shaped and pencil beam, are presented to show the effectiveness and flexibility of the proposed method. [ABSTRACT FROM AUTHOR]

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 nondefective 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. [ABSTRACT FROM AUTHOR]