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In this paper, the problem of array pattern synthesis is considered by developing two array response control algorithms. The devised two algorithms build on the basis of the accurate array response control (A2RC) approach, and both of them have closed-form solutions and low computational complexities. More specifically, the first proposed algorithm realizes multi-point array response control from an any given weight vector, and the second algorithm modifies the first one by avoiding the possible beam axis shift. The proposed two algorithms are able to control array responses accurately under the conditions of independence on steering vectors. By applying the first and the second array response control algorithm, two effective pattern synthesis methods for focused patterns and shaped patterns are devised, respectively. Representative examples are presented to demonstrate the performance of the proposed algorithms in array response control and pattern synthesis.

In practical scenarios, there are always array errors, which would increase the sidelobe level (SLL) of the array and distort the performance of the electronic devices consequently. Nevertheless, most of the reported works do not take these unavoidable errors into consideration when implementing array beampattern synthesis. To remedy this problem, a low sidelobe beampattern synthesis approach is proposed in the presence of array errors based on the bat algorithm (BA). In particular, the covariance matrix of the sidelobe region in the presence of array errors is incorporated into the optimization problem. Generally, there are many factors that would contribute to array errors in practical scenarios. Therefore, to reduce the influence of the uncertainty characteristic of the errors on the low-SLL beampattern synthesis, the statistical mean method is utilized to obtain a robust calculation of the covariance matrix in the presence of array errors. Theoretical analysis using signal processing technique and electromagnetic simulation using Ansoft HFSS workbench are combined to testify the effectiveness of the proposed approach. Numerical results show that peak SLLs (PSLLs) of around −22dB and −20dB can be respectively achieved in the above two simulation situations with the obtained weight vectors.

Phase-only nulling with low sidelobe level is a problem of interest in array synthesis which is a tedious problem without an analytical solution. In this communication, a novel framework for the phase-only nulling based on radial basis function neural network (RBFNN) is proposed to predict the phase adjustment for the array pattern nulling with sidelobe control. In the process of network training, the parameters of the RBFNN are optimized simultaneously based on the self-adaptive differential evolution (SADE) algorithm, which aims to improve the approximation ability and reduce the complexity of the network. Simulation results of the optimized RBFNN models show compact network structure and form the array pattern under desired performance with good generalization capability.

This letter presents a rotation-based optimization method for pattern synthesis of subarrayed phased arrays. In order to keep a good beam scanning ability at different steering angles, the optimization problem is reasonably defined where the objective is taken as minimizing the maximum sidelobe level at a series of steering angles, and both the arrangement variables and the scanning variables are optimized simultaneously. The mutual coupling of the iteratively rotated arrays is rigorously considered in the synthesis. In order to solve the synthesis problem effectively, the design sensitivities are derived analytically and the synthesis is actualized by using a gradient-based algorithm. Typical examples, with considering different regular subarray configurations and the state-of-art irregular subarray configurations, are provided to validate the effectiveness of the proposed approach.

In many practical applications, the antenna arrays are not accurately implemented as desired, resulting in the degradation of sidelobe level. This letter proposes a robust pencil beam pattern synthesis (PBPS) algorithm that is adaptive to the uncertainties of array position. The proposed algorithm, first, sets up the position-variation-related PBPS optimization problem, and then rewrites the position-related parameter, i.e., the array factor, into a high-order Taylor expansion with respect to the array position variation. Thereafter, an iterative processes are designed to estimate the position variation. Finally, the optimal array excitation is calculated by solving the related PBPS problem, in which the estimated array position is used. Simulations with both isotropic element pattern and active element pattern are carried out and the results are compared with the results achieved from the existing work to validate the superiority of the proposed algorithm.

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.

We present a cylindrical dual-polarization phased array antenna for weather surveillance radars that features high isolation, matched copolar beams, low sidelobe levels, and adaptive null steering. We present a crossed dipole antenna element to replace the patch antenna on the currently deployed cylindrical polarimetric phased array radar (CPPAR). The crossed dipole element offers suppressed surface wave and lower coupling between adjacent elements of an array. As a result, we achieved lower backlobe and sidelobe levels, and a higher match between copolar beams of CPPAR compared to the currently deployed multi-layer patch antenna. Further reduction of the sidelobe level and adaptive null steering are obtained using a modified particle swarm optimization. The proposed null steering mitigates the interference among the four concurrent beams of a cylindrical phased array radar. The improvement in CPPAR radiation characteristics has been verified by comparing the presented crossed dipole antenna’s radiation patterns and the existing aperture coupled patch antenna. The proposed crossed dipole phased array can benefit national weather radar networks to provide accurate multiparameter measurements enabling reliable observation of severe weather phenomena.

Various methods have been proposed to control the electromagnetic fields in the near-or far-field region, one of which is to use antenna arrays. This paper reviews a technique, called the method of maximum power transmission efficiency (MMPTE), for the design of antenna arrays and wireless power transmission (WPT) systems. The method is motivated by the fact that all wireless systems aim to maximize the power transmission efficiency (PTE) between the transmitter and receiver and the PTE can thus be considered as a performance index for the design of WPT system and antenna as well. The MMPTE makes use of the PTE as the performance index to be optimized, and reduces a field synthesis problem into a circuit analysis problem, and is therefore easy to master and implement. It overcomes all the challenges associated with conventional array design methods, and is applicable to the design of any type of antenna array in any environment. This paper summarizes the basic theory of MMPTE and demonstrates MMPTE through a number of near- and far-field applications, including focused antennas, smart antennas, shaped beam antennas, end-fire antennas, multi-beam antennas, polarization-reconfigurable antennas, and wireless power transmission systems.

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.

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.

In this article, we investigate a novel iterative antenna array synthesis method. The method is based on the iterative addition of antenna array elements. After defining the synthesis algorithm, we prove that the discrepancy between the goal and the synthesized pattern converges to the theoretical lower bound in the sense of a certain norm. The algorithm is also extended to iteratively replace already placed elements and for the synthesis of multiple goal patterns with the same array geometry but with different excitations. Some numerical examples are shown to illustrate the convergence properties of the proposed method. Possible applications include circularly polarized patterns, since the algorithm can handle the rotation as well as translation of the antenna elements.

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 element rotation and phase optimization technique is utilized for synthesizing saddle-shaped pattern in this paper. As is known, the rotation of a dipole changes the co- and cross-polarized patterns in a given cut of the array pattern. Together with suitable phase control, it is feasible to synthesize shaped power patterns. An example of synthesizing a saddle-shaped pattern with reduced sidelobe level (SLL) and restrained cross-polarization level (XPL) is provided. The synthesized result validates the effectiveness of the proposed element rotation based technique.

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.

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.

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.

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.

In this paper, a multi-shell spherical dielectric lens antenna is synthesized to radiate multi-beams with optimum shaped patterns for radio coverage at millimeter wave (mmW) frequencies. In particular, the design considers the composing characteristics of discrete multi-shell Luneburg lens antenna as an initial structure, and synthesizes its permittivity and sizes of dielectric shells to produce relatively shaped main beam patterns rather than conventional pencil-shapes. It targets to minimize inter-beam overlapping transition regions with slowly varying power density in the coverage boundary, and therefore reduce the ping-pong effect of inter-sector handovers to potentially minimize the inter-cell interferences arising from the over-large gain of pencil beam when the user equipment (UE) is at near the sector boundary far-off the beam peak. After the synthesis, the antenna is implemented at 38 GHz with both numerical simulation and measurement results shown to validate the concept. Successfully validation on the feasibility of beam synthesis in comparison to that of Luneburg lens antennas has been achieved. Discrepancy in fabrication to potentially result in slight radiation degradation is also discussed.

The third edition of the "Phased Array Antenna Handbook" is a very welcome addition to the antenna field. It brings together many ideas and techniques that one would normally have to search through the literature to find. The book is a comprehensive treatment of phased array antennas written by a single author, and it is thus an integrated text that flows smoothly from one topic to another. The publication does not contain homework problems, but the material is presented in such a sufficiently explanatory manner that it could be used as a textbook for a course on phased or antenna arrays, in general, or as a supplement to a course on antennas. The book contains nine chapters, and it has a total length of 530 pages. The text focuses on the antenna aspects of phased arrays and, thus, focuses on aspects related to the radiation patterns of a phased array, along with the antenna elements that are used in phased arrays, and other antenna-related concepts such as mutual coupling in antenna arrays (and their associated effects on scan behavior such as scan blindness). Phased arrays are steadily gaining in relevance with applications in 5G and many other systems, both military and commercial. Better affordability and a wider variety of applications ensures this positive trend. Subsequently, this third edition is a most welcome addition to the antennas and propagation community. This latest edition has been updated to include new contributions to scanning antennas based on reflectors and lenses, as well as thinned arrays, and a more contemporary presentation of numerical methods for pattern synthesis has also been provided. The book provides a comprehensive coverage of all aspects of phased arrays from an antenna point of view, and it also provides an excellent overview of systemlevel aspects of phased arrays in the first chapter. It is very well written by a leading expert in the field, and it is one of the few texts written entirely on phased arrays. As such, it is a must-have publication for every antenna engineer, system engineer, scientist, or practitioner who works with or is interested in phased arrays. This book will also make a great supplement for instructors who teach a course in antenna engineering and who wish to cover phased arrays as part of their course topics.

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.

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.

In this paper, the problem of pattern synthesis with antenna arrays is addressed, and new approaches based on the recently developed accurate array response control ( $ {\textrm {A}}^{2}\textrm {RC} $ ) algorithm are presented. It is shown that the array weight vector obtained by the $ {\textrm {A}}^{2}\textrm {RC} $ algorithm to control the normalized response at a single direction in each step belongs to a specific set. Thus, an appropriate weight vector chosen from the intersection of weight vector sets corresponding to the desired responses at multiple directions is capable of simultaneously controlling those responses. This results in the so-called multipoint accurate array response control ( $ {\textrm {MA}}^{2}\textrm {RC} $ ) algorithm. Moreover, in order to avoid possible beam axis shift in pattern synthesis, a modified $ {\textrm {MA}}^{2}\textrm {RC} $ ( $ {\textrm {M}}^{2}{\textrm {A}}^{2}\textrm {RC} $ ) algorithm is proposed by imposing a derivative constraint on the direction of beam axis. Representative numerical examples are provided to demonstrate the effectiveness of the proposed $ {\textrm {MA}}^{2}\textrm {RC} $ and $ {\textrm {M}}^{2}{\textrm {A}}^{2}\textrm {RC} $ algorithms for multipoint responses control and pattern synthesis.

Numerical pattern synthesis (NPS) algorithm based on adaptive array theory is an effective spatial power pattern synthesis method for antenna arrays. In this letter, instead of using the artificial interferences weighted on the total power pattern in the conventional NPS algorithm, a generalized two-dimensional (2-D) NPS algorithm is proposed in which two weighting functions are assigned to control the copolarization and cross-polarization patterns, respectively. The weighting functions are iteratively updated until both the sidelobe and cross-polarization levels reach their prescribed ones. Two numerical examples for synthesizing the patterns of a linearly polarized planar array and a circularly polarized cylindrical array are provided to validate effectiveness and advantages of the proposed generalized 2-D NPS algorithm.

This letter addresses the problem of phase-only antenna beampattern synthesis. With the given magnitudes of the weight vector, we introduce a scaling factor to accurately represent the shape constraints on both the mainlobe and sidelobe regions. Moreover, we derive an iterative optimization method to solve the resultant optimization problem efficiently. The performance of the proposed method is demonstrated via numerical examples.

An optimization approach based on alternating projection (AP) is proposed to generate low earth orbit (LEO)-satellite-borne multiple patterns with isoflux coverage. The purpose is to find a common amplitude distribution and different phases corresponding to the different patterns. The common amplitudes are with finite levels, which are calculated adaptively in the iteration. To demonstrate the good performance of the proposed method (TPM), synthesis results of multibeam patterns using TPM and modified AP (MAP) are compared in Section IV .

Determining the mainlobe region of an arbitrary pattern is a critical problem in the two-dimensional numerical pattern synthesis (2-D-NPS) method in which a number of artificial interferences with appropriate powers are distributed outside of the mainlobe region. In this communication, a novel mainlobe region determination procedure based on the seeded region growing (SRG) method is proposed. Two different stopping criterions are introduced. Several numerical synthesis examples for uniformly and nonuniformly spaced planar arrays as well as a cylindrical array with directive elements, are presented to validate the effectiveness of the 2-D-NPS with the proposed mainlobe determination procedure. The two stopping criterions are also compared with these examples.

A new method for the synthesis of linear and planar arrays having prescribed beamwidth and sidelobe levels and a minimum number of elements is proposed. In the method, the number of elements in an array is minimized while constraining the amplitude-response error in the mainlobe region, the attenuation in the sidelobe region, and the array dimensions. An iterative constrained optimization method is used where the amplitude-response error is linearly approximated at each iteration while concurrently minimizing a re-weighted L1 norm of the array coefficients. To ensure robustness of the array, we constrain a sensitivity parameter, namely, the white noise gain, to be above a prescribed level. Furthermore, the method also provides the additional flexibility of controlling the array dimensions, symmetry properties, and element positions of the array. Two variants have been developed: In the first variant, both the array coefficients and the positions of the elements are optimized; in the second variant, only the array coefficients are optimized while the elements are fixed at predefined positions. Experimental comparisons with several state-of-the-art competing methods show that the proposed method provides greater flexibility of controlling the robustness, beampattern response error, array dimensions, and element positions while at the same time the number of elements is less than or equal to that of the competing methods.

The design of monopulse radar systems requires the synthesis of both a sum pattern and a difference pattern, which is quite flexible and hard to be optimized for subarrayed antennas. In this study, innovative approaches to synthesize the optimal sum and difference patterns independently for subarrayed monopulse arrays are presented. By exploiting the relationship of the subarray partition and optimal excitations, the synthesis problem is formulated as the clustering of a set induced by the optimal excitations. Thus, the optimal subarray partition is transformed to a clustering problem. A clustering method is presented to solve the array synthesis with uniform excitation at element level. Furthermore, an improved approach is proposed to synthesize low sidelobe patterns. When compared with several classical approaches, various numerical experiments validate the effectiveness and potentiality of the proposed methods.

This communication introduces a hybrid invasive weed optimization and particle swarm optimization (IWO/PSO) algorithm dedicated to pattern synthesis of conformal arrays. A 3 $\, \times \,$ 9 cylindrical conformal microstrip array is studied to demonstrate the proposed algorithm. The active element pattern of each element in the conformal array is extracted and the phase and amplitude of each excited voltage are optimized to achieve the required goals using the hybrid IWO/PSO algorithm. The results indicate that, compared with standard IWO and PSO algorithms, the introduced hybrid algorithm maintains the respective advantages of the IWO and PSO algorithms while excluding their respective deficiencies. Moreover, the hybrid algorithm is very reliable in achieving global optimality.

Reducing the computational cost of large array pattern synthesis is attractive in many applications. In this paper, a fast pencil beam pattern synthesis method for large nonuniform antenna arrays is proposed. This method is based on an interpolation in a least square sense and iterative fast Fourier transform (FFT), i.e., interpolate the nonuniform distributed elements into uniform virtual elements, and then apply FFT to synthesis the uniform array. Thanks to the efficiency of FFT, the proposed method is much faster and can handle much larger arrays than the existing methods. To guarantee the interpolation accuracy, the choice of the interpolation parameters is discussed. Both linear and planar nonuniform array examples are shown to validate the advantages of the proposed method.

In this letter, a modified differential evolution (DE) based on harmony search algorithm is developed for the linear aperiodic array synthesis. By adding the parameter selection strategy into the classic differential evolution, the modified DE combines the good local search capability of the classic DE and the great search diversity of harmony search algorithm. The pattern optimization simulations of the linear aperiodic array verify that it converges faster and requires less computation.

A novel algorithm on beam pattern synthesis for linear aperiodic arrays with arbitrary geometrical configuration is presented in this paper. Linear aperiodic arrays are attractive for their advantages on higher spatial resolution and lower sidelobe. However, the advantages are attained at the cost of solving a complex non-linear optimization problem. In this paper, we explain the Improved Genetic Algorithm (IGA) that simultaneously adjusts the weight coefficients and inter-sensor spacings of a linear aperiodic array in more details and extend the investigations to include the effects of mutual coupling and the sensitivity of the Peak Sidelobe Level (PSL) to steering angles. Numerical results show that the PSL of the synthesized beam pattern has been successfully lowered with the IGA when compared with other techniques published in the literature. In addition, the computational cost of our algorithm can be as low as 10% of that of a recently reported genetic algorithm based synthesis method. The excellent performance of IGA makes it a promising optimization algorithm where expensive cost functions are involved.

This letter proposes an optimal difference pattern synthesis with polarization control ability for arbitrary arrays. The joint synthesis of the polarization and spatial power patterns are formulated as a convex optimization form that can be efficiently solved by existing numerical methods. The proposed synthesis method, which has no limitation on the array geometry and element pattern, is flexible and applicable to arbitrary arrays. Two typical examples, the linear arrays for circular polarization synthesis and the cylindrical arrays for elliptical polarization synthesis, are presented to testify the potentiality of the proposed method.

A numerically-efficient technique based on the Bayesian compressive sampling (BCS) for the design of maximally-sparse linear arrays is introduced. The method is based on a probabilistic formulation of the array synthesis and it exploits a fast relevance vector machine (RVM) for the problem solution. The proposed approach allows the design of linear arrangements fitting desired power patterns with a reduced number of non-uniformly spaced active elements. The numerical validation assesses the effectiveness and computational efficiency of the proposed approach as a suitable complement to existing state-of-the-art techniques for the design of sparse arrays.

The present paper proposes a new approach to constrained optimal pattern synthesis for a circular ring array with ultra-Iow-sidelobe levels. The approach uses an artificial neural network (ANN) with hidden Bessel activation functions, trained using the Levenberg-Marquardt (LM) algorithm. The proposed approach is capable of producing minimal sidelobe levels for an arbitrary pattern shape using only a few iterations, and without high memory requirements as compared to existing alternatives.

An improved synthesis procedure is presented in this letter for the design of waveguide slot arrays directly integrated on the substrate of the exciting microstrip line. To take into account the smallness of the waveguide height, the standard shunt-admittance model usually adopted for the single radiating slot is properly modified into an improved T-network model. Accordingly to this choice, a two-step synthesis procedure is developed to accurately determine the radiating slots' parameters. Experimental validations are discussed for the design of an 8-GHz linear array with a -20-dB Taylor pattern.

Given an antenna array of N elements, we deal with the problem of finding an array pattern that approximates a desired pattern, while: a) null constraints are imposed in M(les N - 2) assigned directions; b) an upper bound D is imposed on the dynamic range ratio (DRR) of the excitations. At first we show that the system of constraint equations has solutions if and only if D ges D0, where D0 is a parameter depending on the null directions, and describe a method to evaluate D0. Then we propose two simple and fast algorithms to solve the synthesis problem and show their effectiveness by numerical examples. Statistical results show that usually D0 = 1 when M is small compared to N, thus exact nulls can be formed for any D ges 1. This result provides an insight into the numerical results.

A new neural network-based method able to perform synthesis over real radiating structures in presence of obstacles is presented. The method is based on the ability of neural networks to establish a relation between inputs and outputs from a previous training procedure with known sets of pairs input/output. If such sets are obtained using a full-waveform analysis tool, a neural network can estimate the voltages that must be applied to the radiating elements of an array in order to get a desired radiated field distribution, taking into account interactions between elements and the presence of obstacles in a near environment

This correspondence proposes a method for array pattern synthesis of a concentric ring array that yields invariant array pattern over a certain frequency band for beamforming in three dimensions. The proposed method uses the Fourier-Bessel series to determine the weights from different rings to form the overall array pattern. Simulation examples are given to illustrate the proposed method.

A novel neural-network (NN)-based technique for antenna array synthesis and a prototype of antenna array designed using it are presented. This technique is able to calculate the voltages that must be applied to the radiating elements considering all the physical properties of each element of the array and the coupling effects between all of them.

The synthesis of unequally spaced large arrays is computationally unapproachable without using an optimization technique. In complex structures, gradient implementations converge to local minima and cannot be used to obtain a desired solution. Thus, global search methods are necessary to get specific design characteristics. In this letter, we propose the ant colony optimization (ACO) as an useful alternative in the thinned array design, using the sidelobe level (SLL) as the desirability parameter. Some examples have been proposed and solved to demonstrate the functionality of this technique for both linear and planar arrays

This letter presents a new array pattern synthesis algorithm using the two-step least-squares method. The algorithm utilizes the randomness of the desired pattern phase to design an array pattern. Several numerical examples are presented to illustrate this algorithm.