Antenna Array Synthesis Research Articles

Synthesis of concentric circular antenna arrays using dragonfly algorithm

ABSTRACTDue to the strong non-linear relationship between the array factor and the array elements, concentric circular antenna array (CCAA) synthesis problem is challenging. Nature-inspired optimisation techniques have been playing an important role in solving array synthesis problems. Dragonfly algorithm (DA) is a novel nature-inspired optimisation technique which is based on the static and dynamic swarming behaviours of dragonflies in nature. This paper presents the design of CCAAs to get low sidelobes using DA. The effectiveness of the proposed DA is investigated in two different (with and without centre element) cases of two three-ring (having 4-, 6-, 8-element or 8-, 10-, 12-element) CCAA design. The radiation pattern of each design cases is obtained by finding optimal excitation weights of the array elements using DA. Simulation results show that the proposed algorithm outperforms the other state-of-the-art techniques (symbiotic organisms search, biogeography-based optimisation, sequential quadratic programming, opposition-based gravitational search algorithm, cat swarm optimisation, firefly algorithm, evolutionary programming) for all design cases. DA can be a promising technique for electromagnetic problems.

Synthesis of non-uniformly spaced circular antenna arrays using a data-driven probabilistic model

Synthesis of non-uniformly spaced circular antenna arrays using a data-driven probabilistic model

Synthesis of Conformal Phased Antenna Arrays With A Novel Multiobjective Invasive Weed Optimization Algorithm

AbstractBy virtue of the excellent aerodynamic performances, conformal phased arrays have been attracting considerable attention. However, for the synthesis of patterns with low/ultra-low sidelobes of the conventional conformal arrays, the obtained dynamic range ratios of amplitude excitations could be quite high, which results in stringent requirements on various error tolerances for practical implementation. Time-modulated array (TMA) has the advantages of low sidelobe and reduced dynamic range ratio requirement of amplitude excitations. This paper takes full advantages of conformal antenna arrays and time-modulated arrays. The active-element-pattern, including element mutual coupling and platform effects, is employed in the whole design process. To optimize the pulse durations and the switch-on instants of the time-modulated elements, multiobjective invasive weed optimization (MOIWO) algorithm based on the nondominated sorting of the solutions is proposed. A S-band 8-element cylindrical conformal array is designed and a S-band 16-element cylindrical-parabolic conformal array is constructed and tested at two different steering angles.

PEEC-Based Multi-Objective Synthesis of Non-Uniformly Spaced Linear Antenna Arrays

Linear antenna arrays consisting of dipole antennas find wide applications in wireless communication systems. Typically, arrangements with uniform spacing between the array elements are applied to gain highly directive radiation patterns. In the present paper an antenna array arrangement with non-uniformly spacing between the array elements is synthesized in the multi-objective sense. The optimization relies on the firefly algorithm and the PEEC method.

Development of an Enhanced Ant Lion Optimization Algorithm and its Application in Antenna Array Synthesis

In order to design a highly effective communication system, antenna plays a vital role and antenna array adds to the performances. And to achieve such a goal, the crucial challenge is to determine the optimum spacing between the elements and their excitations. In order to address this issue a novel optimization technique named as enhanced ant lion optimization (e-ALO) algorithm has been developed by modifying the basic Ant lion optimization algorithm. Further, to validate the efficacy of the proposed algorithm, few benchmark functions have been successfully tested and significant improvement is obtained in comparison to other reported optimization approaches. The proposed scheme is applied to antenna array synthesis problem to optimize the inter-element spacing and excitation of the elements for different antenna geometries, with an objective to minimize the sidelobe levels while keeping other constraints within boundary limits. The encouraging results obtained from the study have emphatically placed the proposed e-ALO algorithm in the optimization arena as a dominant player.

Improved-resolution millimeter-wave imaging through structured illumination.

A resolution-improved active millimeter-wave (MMW) imaging structure, based on the theory of structured illumination, is proposed in this paper. The structured illumination is a well-defined concept for surpassing the diffraction limit in optical microscopy, where imposing grating patterns on the targeted object could help in moving the object frequency spectrum along the desired direction in the spatial frequency domain. This frequency shift helps in passing different parts of the object's frequency spectrum through the diffraction filter. The combination of resultant images provides a framework to pass a wider frequency band of the object, thereby achieving super-resolution. This idea has not yet been employed for MMW image resolution improvement due to practical limitations in producing the desired grating patterns. Therefore, a desired fringe pattern is produced here and tailored for a MMW imaging system through antenna array synthesis. In the proposed scheme, the structured illumination has been implemented for improving the MMW image resolution. Furthermore, an adaptive approach has been proposed in order to generalize the structure for resolution improvement in all required directions in a very fast manner. Electromagnetic simulation results show at most twofold improvement in the image resolution through the proposed MMW imaging structure.

Model-based synthesis of shaped-beam patterns with the minimum number of elements: a state-space method

ABSTRACTConventional antenna array synthesis methods can give good performance for uniform spaced antenna arrays within desired performance bounds. However, due to the restriction of uniform antenna element spacing, a lot of elements are required. Because of the above-mentioned drawback, in this paper, a new approach is presented to synthesise uniform spaced antenna array using the minimum number of elements. This approach introduces the state-space model to represent the desired discrete array pattern that is sampled uniformly from −1 to 1 corresponding to 0–180°, then uses the desired sampled array pattern directly to construct the forward–backward data matrix that is introduced to estimate the model parameters, from which the locations and excitations of the new antenna elements can be extracted. The appropriate roots that are located on the unit circle are selected to obtain new radiation pattern. Simulation results show the viability for both shaped-beam and pencil-beam designs.

Non-uniform single-ring antenna array design using wavelet mutation based novel particle swarm optimization technique

Side lobe level (SLL) reduction is the key challenge in antenna array synthesis. In order to achieve low SLL in array pattern, many conventional optimization methods are proposed to handle complex, nonlinear and non-differentiable array factor of antenna array. In this article, we present an improved optimization scheme; Wavelet Mutation based Novel Particle Swarm Optimization (NPSOWM) for the synthesis of various single-ring planar arrays of isotropic antenna elements. The primary objective is to achieve the radiation pattern with minimum SLL and maximum directivity for the non-uniform, planar circular array (CA), hexagonal array (HA) and elliptical array (EA) antenna. The array pattern synthesis is done based on two parameters of the array; namely, excitation amplitude and element spacing. Two design examples are presented which illustrate the effectiveness of the NPSOWM algorithm. As compared with conventional optimization techniques like genetic algorithm (GA), simulated annealing (SA), particle swarm optimization (PSO) and its variant NPSO, NPSOWM outperforms with the goal of maximum SLL suppression.

Main Beam Controlling Planar Antenna Array Design and Synthesis for Square Kilometre Array and Satellite Applications

Antenna arrays are currently being used for ultra sensitive radio observations in the project called Square Kilometre Array (SKA). In this paper, a planar array has been proposed to match high spatial resolution and high sensitivity requirements of the SKA, and satellite applications. The proposed design offers a well-controlled and elliptically shaped main beam. In addition, optimized thinned configuration provides minimum side lobe peaks and high directivity by applying modified binary Genetic Algorithm (GA). Design-induced modification in GA with a double-stage uniform crossover operation has been proposed. Array factor, forming the cost function with the constraint of uniform side lobe pattern, has been derived. At first, the design has been examined for side lobe peaks, side lobe pattern, and directivity in the orthogonal planes (φ = 0 and φ = π/2). For direction-specific optimization, design offers a directivity of 32 dB and a peak side lobe level of −25 dB. A comprehensive investigation involving optimization in all the planes (φ from 0 to π) has been carried out, giving a side lobe peak of −20 dB and a directivity of 30 dB. The achievable 3-dB beam width is 0.088, evidently fulfilling the high-resolution requirement of SKA applications. A performance comparison with several state-of-the-art synthesis methods shows that the proposed design in combination with the modified heuristic approach can provide high directivity and low beam width, well-controlled main beam, and a radiation pattern with quite competitive side lobe peaks.

A Modified Unequally Spaced Array Antenna Synthesis Method for Side Lobe Reduction

A Modified Unequally Spaced Array Antenna Synthesis Method for Side Lobe Reduction

Design of Filtering Microstrip Antenna Array With Reduced Sidelobe Level

For the requirements of efficient integration and simple fabrication, a new codesign approach for a microstrip filter with an antenna array with reduced sidelobe level is introduced in this communication. The microstrip patch antennas and the stub-loaded resonators are used to illustrate the synthesis of a bandpass filtering antenna array. By controlling the coupling strength between the resonators, a uniform or nonuniform power divider network can be obtained. A nonuniform power division is used to reduce the sidelobe level. The equivalent lumped circuit model is developed and analyzed in detail. Two types of eight-element filtering antenna array with uniform and tapered power-distribution among the elements have been designed. Simulated and measured results provide a good verification for the theoretical concepts.

Radiation Performance Characteristic Optimization of Time-Modulated Circular Antenna Arrays

ABSTRACTIn this paper, memetic flower pollination algorithm (MFPA) is proposed for solving the optimal synthesis of time-modulated half symmetric circular antenna array (TMHSCAA) and time-modulated asymmetric circular antenna array (TMASCAA) by controlling the switching time sequence and the excitation phase of each element time intervals and phases. Current excitation and inter-element spacing of each element are kept uniform. A unique cost function has been formulated for both the case studies. Several low-side lobe patterns synthesized from TMHSCAA and TMASCAA have been compared with those of the conventional circular array. A 20- and 36-element TMHSCAA and TMASCAA have been taken as examples. Furthermore, a novel six-ring time-modulated concentric hexagonal antenna array (TMCHAA) design has been considered to check superiority of the MFPA. The cost function has been designed for the concurrent improvement of side lobe level (SLL) and directivity in the new geometry of TMCHAA by an appropriate fine-tuning of the switching time succession and the inter-element separation of the hexagonal ring. Numerical results show that TMHSCAA, TMASCAA, and TMCHAA can be successfully used for the synthesis of low SLLs even if the amplitude excitations and inter-element spacing are uniform. Statistical analysis is also carried out to ensure that the results are significant in terms of the statistics. The results show that MFPA can exhibit a better performance than the other algorithms like real-coded genetic algorithm, particle swarm optimization, and differential evolution for the antenna array synthesis examples.

Pattern Synthesis of Linear Antenna Arrays Using Enhanced Flower Pollination Algorithm

In this paper, a new variant of flower pollination algorithm (FPA), namely, enhanced flower pollination algorithm (EFPA), has been proposed for the pattern synthesis of nonuniform linear antenna arrays (LAA). The proposed algorithm uses the concept of Cauchy mutation in global pollination and enhanced local search to improve the exploration and exploitation tendencies of FPA. It also uses dynamic switching to control the rate of exploration and exploitation. The algorithm is tested on standard benchmark problems and has been compared statistically with state of the art to prove its worthiness. LAA design is a tricky and difficult electromagnetic problem. Hence to check the efficacy of the proposed algorithm it has been used for synthesis of four different LAA with different sizes. Experimental results show that EFPA algorithm provides enhanced performance in terms of side lobe suppression and null control compared to FPA and other popular algorithms.

Design and Synthesis of Antenna Array With Movable Elements Along Semicircular Paths

A reconfigurable antenna array design whose array elements can move along a semicircular path to synthesis radiation patterns is proposed. This movement is simply carried out by stepper motors without using any other actuators. The array factor of the new design is derived in order to construct the objective function and solve the optimization problem of required pattern synthesis. To validate the design, array patterns with single, symmetric double, multiple, and wide nulls are computed by only controlling element rotation angles with a quantized differential evolution algorithm. The results show that the obtained patterns fit in the restriction masks successfully. The method presented in this letter can also provide both symmetric and asymmetric patterns since the array elements have a freedom of movement in two dimensions.

Novel Method for Optimal Synthesis of 5G Millimeter Wave Linear Antenna Array

We will propose a useful method for 5G mm wave antenna array synthesis, based on Genetic Algorithm for the synthesis of linear array with nonuniform interelement spacing. Our design method was used to obtain the optimal position of the elements in order to get the minimum side lobe level and nulls in desired directions. The simulation results verify that proposed method outperforms the previously published methods in terms of suppression side lobe level while maintaining nulls in specified directions. The flexibility of proposed algorithm shows good potential for the antenna array synthesis.

Pattern Synthesis of Coupled Antenna Arrays via Element Rotation

In this work, a pattern synthesis method is presented for coupled antenna arrays via element rotation. The array is rigorously analyzed with a hybrid and full-wave analysis method based on the 3-D finite element method, modal analysis, generalized scattering matrix, and rotation and translation properties of spherical waves, including mutual coupling effects. The co- and cross-polar components are optimized by means of a gradient method, according to a specific cost function, via successive rotations of the elements.

Reconfigurable Antenna Arrays with Phase-only Control in the Presence of Near-field Nulls

In this paper an effective iterative method is presented for the power synthesis of reconfigurable antenna arrays. The algorithm is suitable for arrays of arbitrary geometry, including the case where a large number of elements is involved. The reconfigurability is achieved by phase-only control, so that the excitation amplitude of each array element remains constant during the reconfiguration process. Such amplitudes may be different from one array element to the others, and they are not assigned a priori, but are optimized. Furthermore, the electric field is imposed to vanish in a number of prescribed points of the near-field region, so that a strong field reduction is obtained in a neighborhood of them.

Tolerance Analysis of Antenna Array Pattern and Array Synthesis in the Presence of Excitation Errors

This paper analyzes array pattern tolerance against excitation errors. The nonprobabilistic interval analysis algorithm is used for tolerance analysis of the nonideal uniform linear array in this work. Toward this purpose, corresponding interval models of the power pattern functions are established, respectively, with the consideration of the amplitude errors, phase errors, or both simultaneously, in antenna arrays. The tolerance for the amplitude-phase error of the main function parameters including the beamwidth, sidelobe level, and the directivity is simulated by computer according to the indicators and the actual requirements. Accordingly, the worst admissible performance of an array can be evaluated, which may provide theoretical reference for optimal antenna array design. As for the problem of array synthesis in the presence of various array errors, interval analysis-convex programming (IA-CP) is presented. Simulation results show that the proposed IA-CP based synthesis technique is robust for the amplitude and phase errors.

Reconfigurable Antenna Arrays with Multiple Requirements: A Versatile 3D Approach

This paper proposes a deterministic method for the 3D synthesis of antenna arrays that jointly accounts for far-field pattern reconfigurability, polarization setting, dynamic range ratio reduction, and near-field control. The conceived algorithm, which generalizes some existing solutions, relies on a weighted cost function, whose iterative minimization is accomplished by properly derived closed-form expressions. This feature, combined with the possibility of selecting the weighting parameters, provides a fast and versatile approach, whose capabilities are numerically checked by considering different synthesis problems and array structures in the presence of mutual coupling.

Synthesis of Adaptive Antenna Array using Exponentially Weighted Recursive Least Square Algorithm

Objective: Beam shaping is a powerful means to increase the capacity of antenna system in wireless communication for better transmission and reception of signal. Methods /Analysis: In this paper, an adaptive array arrangement is developed to improve beam shaping for better synthesis of antenna array system. The adaptive algorithm used here is exponentially weighted Recursive Least Square (RLS) algorithm which measures the correction weights by its own optimization which prevents the large inversion correlation matrix. Here the array of n antenna is connected to the adaptive controller which will take the decision whether the beam should access at a specific time. Novelty/Improvements: The convergence rate of mean square error is better here and the performance of RLS algorithm is better when compared to LMS algorithm. Proper beam formation can occur by using this method.