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This letter proposes a method based on primary-dual iteration to address the array pattern synthesis problem of minimizing the peak sidelobe level (PSL) under the constraints of controlled mainlobe ripples and dynamic range ratio (DRR) of current excitations. Especially, when DRR = 1, the phase-only beampattern synthesis problem is solved. Simulation examples are presented to verify the effectiveness of the proposed method in terms of PSL and DRR.

In this letter, a new algorithm is presented for synthesizing large linear and planar arrays. To reduce the system cost and implementation complexity, the large array is partitioned into multiple disjoint subarrays and is only weighted at subarray level. By the approximation of the optimization objective, the pattern synthesis problem is first formulated as a weight matching problem. Subsequently, a clustering methodology named $K$ -means approach is adopted to solve this problem. The proposed algorithm can produce a good-shaped pattern, which has lower peak sidelobe level than that synthesized by the state-of-the-art method. Numerical results demonstrate the effectiveness of the proposed algorithm.

The generation process of difference beam is analyzed from the perspective of beam superposition. By analyzing the continuous linear source, a differential beam synthesis method, which can control the sidelobes level, is proposed with a simple form. The sidelobes level of the difference pattern is determined by controlling the direction of the subbeam and applying the traditional synthesis method, such as Chebyshev method and Taylor method. The proposed synthesis method is theoretical and explicit. Examples are presented for assessing the capabilities of the synthesis of difference patterns. The general distribution function is given.

An efficient multibeam pattern synthesis method for time modulated array (TMA) is proposed in this paper. The aim of this method is to generate a beam pattern on the specified sideband of TMA. The pattern synthesis problem is divided into two stages. In the first stage, the sequential convex optimization method is used to suppress the sidelobe of the center frequency and reduce the amplitude dynamic range ratios (DRR). In the second stage, the iterative convex optimization method is used to realize the multibeam pattern synthesis in the sideband. Owing to the introduction of convex optimization, the proposed method could be more efficient than approaches using a global optimization algorithm. The proposed method is capable of realizing pattern synthesis under different DRR constraints and different beam radiation directions. Numerical examples of two beams and four beams patterns of 1000-element time modulated linear array verify the effectiveness of the proposed method.

Pattern synthesis is a significant research focus in smart antennas due to its extensive use in several radar and communication systems. To improve the optimization performance of pattern synthesis of uniform and sparse linear antenna array, this paper presents an optimization method for solving the antenna array synthesis problem using the Mayfly Algorithm (MA). MA is a new heuristic algorithm inspired by the flight behavior as well as the mating process of mayflies, it has a unique velocity update system with great convergence. In this work, the MA was applied to linear antenna arrays (LAA) for optimal pattern synthesis in the following ways: by optimizing the antenna current amplitudes while maintaining uniform spacing and by optimizing the antenna positions while assuming a uniform excitation. Constraints of inter-element spacing and aperture length are imposed in the synthesis of sparse LAA. Sidelobe level (SLL) suppression with the placement of nulls in the specified directions is also implemented. The results gotten from this novel algorithm are validated by benchmarking with results obtained using other intelligent algorithms. In the synthesis of uniform 20-element LAA with nulls, MA achieved an SLL of −31.27 dB and the deepest null of −101.60 dB. Also, for sparse 20-element LAA, an SLL of −18.85 dB was attained alongside the deepest null of −87.37 dB. MA obtained an SLL of −35.73 dB and −23.68 dB for the synthesis of uniform and sparse 32-element LAA respectively. Finally, electromagnetism simulations are conducted using ANSYS Electromagnetics (HFSS) software, to evaluate the performance of MA for the beam pattern optimizations, taking into consideration the mutual coupling effects. The results prove that optimization of LAA using MA provides considerable enhancements in peak SLL suppression, null control, and convergence rate with respect to the uniform array and the synthesis obtained from other existing optimization techniques.

A low-profile transmissive metasurface is proposed to synthesize contour beam pattern for a European region. A slot array feed is used to illuminate same size metasurface aperture with a plane wave at a near field distance of 24 mm. A two step optimization process is proposed to solve asymmetric and complicated pattern synthesis problem for transformation of plane wave to contour beam pattern using modified Alternating Projection Method (APM). A new subwavelength 4-arm spiral element is proposed to achieve desired performance for contour beam pattern synthesis in $Ku$ band centered at 12.5 GHz. A prototype of low profile transmissive metasurface is also fabricated and measured to verify its gain and bandwidth performance for contour beam pattern synthesis for the European region.

The techniques on the generation of multiple solutions in shaped-beam pattern synthesis are standardly focused on the use of patterns with complex nature as input. Otherwise, in order to derive a symmetric pure real distribution from the canonical pattern synthesis techniques, a generation of a pure-real pattern has to be imposed. In the present work, the exploitation of the multiplicity of the shaped pattern generated by this symmetric pure real distribution is proposed, without constraining the solutions to necessarily meet the pure-real pattern requirement. Therefore, an increase on the degrees of freedom is produced and a greater number of continuous distributions (presenting different natures) is achieved, by omitting the restrictions found in the state-of-the-art methodologies. Thus, a general multiplicity of solutions can be reached and the design protocol can increase its number of alternatives for facing different feeding network structures. In such a way, this article is devoted to illustrate the improvements in terms of number of feasible solutions reached by the general method, including alternative symmetric pure real distributions as input within the procedure. In this manner, two different approaches, constraining the pattern to present the same number of ripples or a similar main beam width, are discussed. Examples of both Taylor distributions linear and circular are illustrated.

An optimization method of pattern synthesis is proposed for peak sidelobe level (PSLL) suppression and null controlling via element rotation and phase optimization. The purpose of this method is to...

Antenna arrays with low sidelobe patterns and high directivities are very desirable in practice and represent a key success for many communication systems such as radio telescopes, satellites, fift...

One of the ultimate targets of array pattern synthesis is to maintain the mainbeam while suppressing the peak sidelode level (PSLL) within a smaller aperture size. The mainbeam gain proportionally increases with the aperture size, whereas the PSLL is uncorrelated approximately. This regular is useful for adjusting the array pattern as changing the aperture size. However, when the mutual coupling effect among the coupled array elements is considered, for some kinds of nonuniform arrays, e.g., the concentric ring array or the concentric elliptical array (CEA), the PSLL property would change significantly when the same array arrangement with different aperture sizes is used. On the purpose of both the PSLL suppression and the aperture reduction, this letter presents a pattern synthesis approach of real coupled CEAs. The form of elliptic ring is mainly introduced for the aperture reduction, and the ellipse-axis ratio, together with the ring radii and the position of each array element along the elliptic rings, are optimized simultaneously for the PSLL suppression. Typical examples are provided to validate the effectiveness of the synthesis approach. This approach also gives an alternative way for the adjustment of real coupled arrays after the theoretical synthesis.

This letter proposes a new power gain pattern synthesis-based (PGPS-based) algorithm for maximizing the minimum array power gain in a wide-beam mainlobe via linear programming. The existing PGPS-based algorithm has been proved to outperform the existing shaped beam pattern synthesis based (SBPS-based) algorithms. However, its optimal solution to the PGPS problem can only be obtained via iterative procedures and its convergence cannot be theoretically guaranteed. One disadvantage of this nonconvergence is that the desired sidelobe level (SLL) might be unobtainable. This letter reformulates the original PGPS problem and transforms it into an approximately equal convex form. As a result, the convergence of the proposed algorithm is ensured and the desired SLL can always be obtained. Moreover, the proposed algorithm can accelerate the computational time. Its performance is assessed with HFSS simulated data by comparing it with the existing PGPS-based algorithm and the SBPS-based algorithms.

An improved gravity search algorithm, adaptive gravity search algorithm (AGSA), is proposed to solve the problem that the gravity neutralization caused by the cumulative effect of particle inertia mass at the end of iteration, which will affect the optimization performance. An adaptive decay factor is designed, which can produce different gravitation values at different iteration stages of the algorithm and accelerate the mining ability of the algorithm at the later iteration stage. In order to enhance the memory ability of the algorithm, the influence of elite particles is added to the realization of the speed to expand the exploration ability. The improved algorithm is used to optimize uniform concentric ring array, the main lobe width optimized by the AGSA is 6.7°narrower and the side lobe level is 5.1 dB and 1.8 dB lower than the algorithm in the literature. It is clear that the pattern obtained by AGSA meets the desired pattern very well. Moreover, when the number of iterations is 2 000, the fitness value of the improved algorithm is increased by 30%. It can be seen that AGSA outperforms the algorithm in the literature in evolutionary speed and accuracy. Sparse concentric ring array also has the same optimization results. The effectiveness of the proposed improved algorithm in solving the array pattern synthesis is proved.

In this paper, a chamfer distribution antenna array is designed to generate a deflecting circular-polarized vortex beam carrying orbital angular momentum (OAM) mode. When the vortex beam is designed with a deflection angle, the sidelobe of the vortex beam will deteriorate. In order to solve this problem, an optimized array design is presented in this paper. Inspired by the Chebyshev distribution array synthesis method, the antenna elements in the four corners of the antenna array are cut out to realize the chamfer distribution array. Therefore, the sidelobe level of the deflected vortex beam can be effectively suppressed. Moreover, a simplified feeding network is designed to reduce the feeding network complexity by using circularly polarized structural center antenna element. The designed antenna array is simulated, fabricated, and measured at center frequency of 4.25 GHz in C-band. The far-field radiation pattern of the deflected vortex beam and the near E-field OAM vortex beam distribution are simulated and measured to verify the effectiveness of the proposed design method for sidelobe suppression array.

A two-dimensional (2-D) discrete dielectric lens antenna is designed to radiate fan-shaped multi-beam patterns for gain stability in beam switching. The target is to minimize adjacent-beam overlapping transition regions and provide sufficient and similar gains for all field angles when the antenna is employed in a mobile device. This design starts with a conventional 2-D Luneburg lens antenna, and distorts its dielectric permittivity and the sizes of discrete dielectric rings to defocus the pencil beam patterns into shaped ones with a relatively flat pattern for uniform field distribution. The design is realistically implemented at 38 GHz with both simulation and measurement results shown to validate the concept. Successful validation of feasibility in beam synthesis is achieved. Fabrication discrepancy to result in slight radiation degradation is also discussed.

The problem of optimised design of diversely polarised sparse array for joint synthesis of spatial and polarisation beampattern is addressed in this Letter. Two kinds of polarised array configurations, cocentred and non-cocentred crossed-dipole arrays, are considered. Minimum interelement spacing constraint along with non-cocentred constraint are involved in the design methods by using two discrete linear operators. The optimisation process can be formulated as a mixed-integer quadratically constrained programming problem which guarantees the optimal solution of the sparse array configuration. Comparison examples with state-of-the-art method validate the advantages of the proposed method in terms of the reduction of required element number and the enlargement of adjacent element spacing.

In this paper, the pattern synthesis of conformal antenna array using Salp Swarm Whale Optimization Algorithm (SSWOA) algorithm is proposed. The proposed hybrid algorithm is the combination of Salp Swarm Optimization (SSA) and Whale Optimization Algorithm (WOA). In the proposed algorithm, the SSA algorithm plays the role of guiding the evolution and the WOA algorithm works as an assistant. Moreover, after updating the salps position, with WOA the best known position are evolved to enhance the optimum search ability. When applied to antenna array pattern synthesis by taking advantages of SSA and WOA, the proposed optimization has high convergence accuracy and faster convergence speed. Several typical test functions and optimization examples of a linear array pattern synthesis are illustrated to show the performance of the hybrid algorithm. Experimental results show that the proposed hybrid algorithm is superior to SSA and WOA when applied to Sphere, Griewank, Rosenbrock, and Rastrigin test functions. Keywords: Pattern synthesis, Conformal antenna, Convergence speed, Linear array, Sphere, Griewank, Rosenbrock, Rastrigin

In this paper, a new array synthesis approach is developed for the design of reconfigurable sparse arrays radiating sum and difference patterns. The proposed approach provides a significant...

Pattern synthesis of non-uniform elliptical antenna arrays is presented in this paper. Only the element positions of the antenna arrays are optimized by the combination of differential evolution (DE) and invasive weed optimization (IWO) to reduce the peak side lobe level (PSLL) of the radiation pattern. In order to avoid the overlap of the array elements, the minimum spacing of the adjacent elements is constrained. Also, the beam width of the radiation pattern can be constrained effectively. Three elliptical antenna arrays that have 8, 12, and 20 elements are investigated. The synthesis results show that the introduced method can present a good side lobe reduction for the radiation pattern. Compared with other optimization methods, the method proposed in this paper can obtain better performance.

The synthesis of frequency-scanned monopulse radiation patterns using an array of two leaky-wave antennas (LWAs) is demonstrated. The LWA array must be designed with appropriate shifted frequency-dispersion responses to fulfill the desired monopulse-scanning specification over the required bandwidth and number of channels. This is demonstrated using two manufactured LWAs in half-width microstrip technology, designed to scan in the band from 2.39 to 2.65 GHz covering a field of view (FoV) from −80° to +80° and using three frequency channels. Also, this paper addresses the procedure to estimate the direction of arrival (DoA) of an incoming beacon RF signal composed by prescribed tones distributed in the scanning band. This type of multicarrier beacon signals can be produced in wireless systems which allow for frequency-hopping operation. It is demonstrated that the proposed monopulse DoA-estimation technique combines good angular resolution and wide FoV using a simple passive antenna structure.

A hybrid approach to the synthesis of sparse arrays radiating shaped or focused beampattern is presented in this paper. Specifically, an iterative scheme is used where the prescribed pattern response in the mainlobe peak direction is cast as a multi-convex problem at each step that the non-convex lower bound constraint is relaxed while including a reweighted l(1)-norm minimisation based on the magnitudes of the elements. Numerical tests, referred to benchmark problems, show that the proposed method achieves improved radiation performance by using fewer number of radiating elements.

Autocorrelation matching method is proposed for phase-only synthesis of power pattern of linear antenna arrays. This method is based on equating the autocorrelation coefficients of an array having given amplitude of excitations to those of a previously designed amplitude-phase array. Some examples are brought to verify the effectiveness of the proposed method for both pencil-beam and shaped beam patterns.

In this paper, we present two array response control algorithms for pattern synthesis with the aid of oblique projection. The proposed algorithms are developed on the basis of the weight vector orthogonal decomposition (WORD) approach, and both of them can control the array responses of multiple points starting from an arbitrarily given weight vector. They provide closed-form expressions and thus are computationally attractive and convenient to implement. Furthermore, for the preassigned angles to be controlled, the array responses can be adjusted flexibly and separately, and hence, the process of response control can be readily accomplished without complete recalculation, if some of the desired levels require adjustments. In addition, the second proposed algorithm modifies the first one and realizes the array response control without a beam axis shift. By successively performing the proposed algorithms to adjust the response to meet certain requirements, the array pattern can be synthesized. Extensive examples are provided to demonstrate the performances of the proposed algorithms in array response control and the effectiveness in pattern synthesis.

In this paper, we propose an array pattern synthesis scheme using semidefinite programming (SDP) under array excitation power constraints. When an array pattern synthesis problem is formulated as an SDP problem, it is known that an additional rank‐one constraint is generated inevitably and relaxed via semidefinite relaxation. If the solution to the relaxed SDP problem is not of rank one, then conventional SDP‐based array pattern synthesis approaches fail to obtain optimal solutions because the additional rank‐one constraint is not handled appropriately. To overcome this drawback, we adopted a bisection technique combined with a penalty function method. Numerical applications are presented to demonstrate the validity of the proposed scheme.

The 4-D antenna arrays with the irregular array topology have great advantages in simplifying the beamforming network and reducing the cost. However, the complexity of such synthesis problems limited their development. An effective joint optimization approach based on the maximum-entropy model is proposed for the pattern synthesis of 4-D irregular arrays. By introducing the entropy concept into 4-D irregular arrays, the original synthesis problem is simplified into two problems, which can be solved in two steps separately. In the first step, the optimization of the topology of 4-D irregular arrays characterized by domino-shaped tiles is performed, based on the principle of entropy maximization. The genetic algorithm is introduced to solve the pure integer optimization problem. Then, the differential evolution algorithm is used to synthesize the desired radiation pattern based on the optimized array topology. Consequently, the joint optimization approach significantly improves the overall synthesis efficiency. Three numerical examples are presented to demonstrate the effectiveness of the proposed approach. Moreover, the numerical results show that the 4-D irregular arrays designed by the proposed approach have the excellent beam scanning ability.

A new multi-dimension to one-dimension transformation (MTOT) approach is presented to synthesize multi-dimensional antenna array pattern. In the new approach the multi-dimensional antenna array pattern synthesis issue is mathematically transformed into a one-dimensional (1D) pattern synthesis issue by taking advantage of the general characteristics of the pattern function, which makes all existing linear array pattern synthesis and beamforming methods applicable to addressing relevant multi-dimensional array pattern synthesis issues. The new method provides a general way for multi-dimensional array pattern synthesis. Simulations of the new approach are conducted to show its effectiveness. The simulation results show that the new method can well accomplish the pattern synthesis mission for different multi-dimensional array configurations.

As a research hotspot in antenna arrays, the time modulated array (TMA) has advantages in pattern synthesis, direction finding, adaptive beamforming, and multi-beams, making it a potential application in satellite communications. This article illustrates how to utilize the TMA in satellite communications, to improve the performance of communication between the satellite and Earth. First, the overview of the TMA is provided. Second, direction finding by the TMA on the satellite is analyzed, which helps to detect and track users on Earth. Third, adaptive beamforming based on the TMA is discussed, which synthesizes the pattern of the generated harmonic component to point to mobile users. Fourth, the multibeam characteristic of the TMA is analyzed to simplify the complexity of a multi-beam system on the satellite. Finally, some conclusions are drawn, and areas of further research are put forward.

© 2013 IEEE. This paper extends the semidefinite relaxation (SDR) method to be capable of synthesizing linearly polarized shaped patterns with accurate control of sidelobe level (SLL), cross-polarization level (XPL), and dynamic range ratio (DRR) of the excitation distribution for arbitrary antenna arrays. In addition, by using the vectorial active element patterns, mutual coupling and platform effect can be also incorporated into the proposed vectorial shaped pattern synthesis. Three examples for synthesizing linearly polarized patterns with different pattern shape requirements and different antenna array geometries have been conducted to check the effectiveness and robustness of the proposed method. Compared to the original vectorial shaped pattern synthesis without DRR control, the proposed method with the DRR control can significantly reduce the obtained DRR which is very useful in many antenna array applications.

This paper presents an approach to pattern synthesis based on the difference coarray of minimum hole arrays (MHAs), based on the relations between the weights on the physical array and the virtual weights on the difference coarray. From these relations, some virtual weights are selected as design variables. The remaining virtual weights and the weights on the physical array are then determined by these design variables. Numerical examples show that, if these design variables are samples of a Kaiser window, the proposed approach can achieve smaller beamwidth or lower sidelobe levels than some existing weight designs for the MHA.

Effective resource utilization is an important problem in the application of array, especially for the new time modulated array. Considering the problem of full utilization of array elements in time modulated array, a sparse optimization algorithm based on discrete variable convex optimization is proposed in this paper. The pattern optimization of equal excitation time modulation array is realized in two stages: In the first stage, the number of working array elements is as low as possible under the condition of suppressing the sidelobe of the central frequency. In the second stage, the sideband is suppressed by iterative convex optimization. The numerical simulation results are compared with other methods to verify the effectiveness of the proposed method in pattern optimization of equal excitation time modulation array. Finally, the optimization performance of the algorithm with different array parameters is verified.

In the present paper, an iterative technique devoted to reproducing efficient footprints with arbitrary boundaries for planar arrays is addressed. The methodology here depicted is based on exploiting the nature of the continuous aperture distribution by expressing it as a Fourier series of moderately high orders. In this manner, the resulting illumination boundary is defined by a target three-dimensional flat-topped pattern composed of stretching and shrinking modified circular Taylor patterns and the maximum order of the series to obtain a good reconstruction is determined by means of the iterative process. Examples and comparisons with the previous literature were conducted by analyzing square and rectangular contoured beams as test cases. Additionally, interesting potentials regarding space applications from a geostationary satellite are outlined by means of the EuTELSAT (European Telecommunications Satellite Organization) European coverage case study. In such a way, its numerical approach was analyzed by including subarray architectures and discussing improvements about dynamic range ratio of the excitations without critical power losses within the illumination region This work was supported in part by the FEDER/Ministerio de Ciencia, Innovación y Universidades-Agencia Estatal de Investigación under Project TEC2017-86110-R. The work of A.A.S.S. is supported by the Xunta de Galicia Postdoctoral Fellowship with reference ED481B 2018/008 SI

This paper presents a metasurface (MTS) to generate a flat-top pattern using phase compensation method. The proposed flat top pattern is realized by diving the entire MTS into four sub regions which directs the beam in different directions. The metasurface is designed with an array of 15x15 unitcells where each unitcell comprises of an four-layered elliptical patch surrounded by a square ring. The beam pointing angle for each sub region is optimized to achieve nearly constant gain throughout the desired angular section. The simulation results show a flat-top pattern with a ripple factor less than 1 dB in the interval [−15° to15°] at the designed frequency of 10 GHz and 12 GHz.

An iterative spatiotemporal Fourier transform (STFT) method is proposed to synthesize a wideband scannable frequency-invariant (FI) pattern for a uniformly spaced linear antenna array. This method applies a modification-and-projection iteration to continuously update the synthesis results. An example for synthesizing a scannable FI pattern with uniform sidelobe level (SLL) is provided to verify the effectiveness and efficiency of the proposed method.

In view of the problem that Artificial Bee Colony (ABC) algorithm is liable to fall into local optimum, an improved ABC algorithm is proposed. Focusing on the selection of algorithm simulated annealing is introduced to the ABC algorithm. In this way precision and search capability of algorithm is improved. This algorithm is applied in bench test functions and its performance is analyzed and compared. Besides the array synthesis of uniform linear array is realized by this method. The simulation results show that the precision of proposed algorithm is much better than the standard ABC and it is effective and feasible in array synthesis application.

In this paper, a method of grating lobes and sidelobes suppression for distributed two-level nested array is presented. The method combines the distributed nested array structure and the pattern product theorem to obtain a distributed two-level nested array two-way pattern, which can effectively suppress the grating lobes and sidelobes. The Chebyshev window is used to design the weights of the transmit array pattern to achieve ultralow sidelobes performance. Numerical simulations are provided for testing the proposed method. Simulation results demonstrate the effectiveness of the proposed method, which will help to improve the detection performance of radar.

Solving the power gain pattern synthesis (PGPS) problem has been proved to be able to increase the array gain instead of solving the shaped-beam pattern synthesis (SBPS) problem. However, the existing PGPS-based algorithm is, sometimes, non-convergent and the worse is its optimal solution is usually seriously affected by the initialized array weight. The paper sets up a new model for the PGPS problem with convex structure. A power gain optimization algorithm for wide-beam synthesis is designed to maximize the minimum gain in the wide-beam mainlobe. The advantages of the proposed algorithm are that it does not need any array weight initialization and its convergence is theoretically guaranteed. Besides, the performance of proposed algorithm is similar to that of the existing PGPS-based algorithm and better than the SBPS-based algorithms.

In this paper, an effective method to synthesize nearfield multi-focus with array antenna is proposed. With the assigned foci positions, we introduce the constrains on both foci and sidelobe regions. Moreover, the designed optimization problem can be solved by the alternating direction method of multipliers (ADMM) effectively. Synthesis numerical comparisons with the existing near-field multi-focus methods indicate that the proposed method can achieve an improved accuracy.

In this paper, a novel method for pattern synthesis of antenna arrays based on dynamic cooperative gray wolf optimizer algorithm is proposed. By introducing the dynamic cooperative weight factor, positions of the three leader wolves are weighted, and then the positions of next generation are updated. The improved algorithm emphasizes the leading role of the leader wolf, but also does not neglect the cooperation between the leadership wolves. Global optimal and local optimal can be well balanced and converge to the optimal solution quickly and effectively. The proposed algorithm has been successfully used to reduce the sidelobe level and form deep null steerings at designated directions which meets the design requirements.

A cylindrical conformal metasurface is introduced for wideband RCS reduction, utilizing the optimized multielement phase cancellation. The metasurface is divided into eight regions containing a total of 40 lattices that are printed on a cylindrically curved ground plane. For different regions of the curved surface, the incident angle and wave path difference caused by the bending of the conformal structure are considered. Hybrid array pattern synthesis and particle swarm optimization are used to control and optimize the interaction between multiple backscattered waves generated by the lattices, so as to realize wideband destructive interference. The designed metasurface can achieve a 10 dB reduction in backscattered RCS under normal incidence for HH polarization from 5 to 6.8 GHz and 7.3 to 10 GHz with the fractional bandwidths of 30.5% and 31.2%, respectively. The estimated and simulated results are in good agreement and prove that the proposed method can be used to solve the wideband RCS reduction of the conformal targets.

A new approach to the problem of focusing the intensity of vector fields into a target point (subject to sidelobe constraints elsewhere) is proposed. While allowing the adoption of completely arbitrary array antennas as radiating systems, the method exploits a nested optimization procedure properly acting on both the field polarization on the target point and the array excitations. By so doing, it is able to improve the performances of existing procedures (that usually handle scalar fields) and to deal with both the near-field (NF) and the far-field (FF) focusing problems in complex inhomogeneous 3-D media.

In this work, a broadband dual-polarized base station array is designed. The 1400MHz-2700MHz band is covered by a single broadband Vivaldi antenna element. The 690MHz-960MHz band is covered by a conventional dipole-like element. The array synthesis has been carried out by time-domain full-wave simulations where excitation is applied to a unit cell embedded in an array. Then, array theory is applied to estimate the far-field of the entire structure. This is computationally efficient, which allows us to optimize the performance of the array with both analytical and numerical approaches.

The aim of this paper is two-fold. First, the trade-off between directivity, beam-width, side-lobe-level, number of radiating elements, and scanning range of planar antenna arrays is reviewed, and some simple ready-to-use formulas for the preliminary dimensioning of equispaced planar arrays are provided. Furthermore, the synthesis of sparse planar arrays, and the issue of their reduction in directivity, is analyzed. Second, a simple, yet effective, novel approach to overcome the directivity issue is proposed. The presented method is validated by several synthesized layouts, the examples show that it is possible to synthesize sparse arrays, able to challenge with equispaced lattices in terms of directivity, with a significant reduction of the number of radiators.

In terms of the high sidelobe level of circular ring array, a pattern synthesis method based on artificial neural network is presented. Under the constraint of circular ring array radius, a circular ring pattern synthesis model is built based on forward neural network firstly; then, a Bessel function is used as the excitation function, and a damped least squares method is used as trained algorithm. The circular ring array sidelobe level and beam direction can be controlled by the new method.

A hybrid method that combines the iterative Fourier transform (IFT) and the algorithm of differential evolution (DE) is proposed to address the synthesis of low sidelobe sparse linear array (SLA) including many elements. Firstly, a thinned linear array (TLA) with the lattices spaced at half wavelength is obtained by the IFT. Then, for the elements of the TLA whose left or right spacing are greater than half wavelength, their placements are selected as the candidates which will be further optimized by the DE, as long as the interelement spacing is not less than half wavelength. Consequently, the convergence pressure of DE is greatly alleviated for the reason that the selected elements only accounts for a small part of the total. Therefore, the SLA with improved sidelobe performance can be obtained at relative low hardware cost. Several numerical instances confirmed the effectiveness of the proposed method.

The pattern synthesis based on the spectral Green's functions for multi-layered perforated dielectric loaded patch antenna is presented. It is conducted by optimising the dielectric superstrate parameters, i.e. relative permittivity (e r) and thickness. To solve the problem of the optimised e r unavailable from market, perforated dielectric superstrate (PDS) is utilised. The equivalence between PDS and homogeneous dielectric superstrate (HDS) in spectral domain is investigated and the effective relative permittivity (e reff) of PDS is studied. Moreover, by introducing e reff, the general optimisation procedure for HDS loaded antenna is also applicable for PDS loaded antenna, which reduces the computational cost significantly. To validate their method, a two-layer PDS loaded patch antenna with E/H beamwidth equalisation was designed, fabricated and measured. Simulations and measurements show that the synthesised antenna has satisfactory performances over the ITU-RS.1068-1994 band from 13.75 to 14 GHz. The half 10 dB E/H beamwidths of 19°/20°, −27 dB cross polarisation and −15.5 dB side lobe level have been achieved.

By 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.

This paper introduces a hybrid genetic algorithm and particle swarm optimization algorithm (GA-PSO) dedicated to pattern synthesis of conformal antenna arrays. Taking advantages of both methods, th...

In order to study the dynamic signature from a wind farm composed of massive wind turbines, a high-frequency model of electromagnetic scattering is developed by combining a shooting and bouncing ray and the array synthesis technique. With the help of image theory and some modifications, the ground effects due to a dielectric rough ground are accounted whereas without modeling physically the infinite ground. Thus, the proposed method can be used to effectively simulate the massive required scattering data under a minimal computational cost for the Doppler analysis of the full-size rotating wind turbines and radar imaging of a wind farm.

In this paper, we propose an improved nondominated sorting genetic algorithm-II with scope constrained (INSGA-II/SC) with three modifications, which are dynamic nondomination strategy, scope-constrained strategy, and front uniformly distributed strategy. Here, the metric for multiobjective optimization mainly focuses on the computation complexity, convergence, and diversity of the final solutions. For a large search space in the initial process and a fast convergence in the last process, dynamic nondomination factor is considered in the rank operator. We can find a manageable number of Pareto solutions that are in the constrained scope instead of the entire Pareto front (PF) to reduce the computation complexity by scope-constrained strategy. In order to obtain a high performance for good representatives of the entire PF, the solutions closer to the uniformly distributed points on the current front will be chosen. In this paper, the proposed methods and two efficient multiobjective optimization methods are used for the optimization of mathematical problems and array pattern synthesis with lower side lobe level (SLL) and null. Numerical examples show that INSGA-II/SC has a high performance of diversity and convergence for the final solutions when compared with the other techniques published in the literature.

This communication presents a simple and useful technique to suppress the radiation sidelobe levels (SLLs) of reflector antennas by embedding reflecting elements around the edge boundary. Due to the fact that sidelobes mainly arise from the edge diffractions, the reflecting elements can alter the phase distribution of induced currents along the edge boundary, and therefore reduce the sidelobes through the destructive cancellation of fields radiated from these elements. The desired phases are found through the implementation of pattern synthesis technique such as genetic algorithm to optimize the SLLs. This technique of edge current phase alternation may be employed, in conjunction with using a tapered feed radiation to illuminate the reflector, to control both amplitudes and phases of edge currents. Thus, the edge diffraction mechanism may be better controlled to optimize SLLs. In this communication, both resonant and nonresonant types of metallic elements are implemented and compared to illustrate their characteristics of radiations in SLL suppression. This technique is particularly useful to suppress the SLLs within a local angular region. Numerical results based on the method of moment analysis are presented to validate the feasibility.