Non-uniform Antenna Arrays Research Articles

Non-uniform optical phased array based on dual-adaption genetic algorithm improved by chaos sequence

To address the issue of diminishing peak side lobe levels (PSLL) in non-uniform optical phased array (OPA) as steering angle increases, we introduce a dual-adaption genetic algorithm (DAGA) based on chaos sequence to optimize the antenna array layout. By leveraging chaos mapping traversal and randomness, this approach enhances the diversity of the initial antenna layout, thereby improving the algorithm's capacity to escape local optima. Concurrently, we also reduce background noise during the array steering process to enhance PSLL at large steering angle. In this study, we optimize non-uniform antenna arrays with 64-, 128-, and 256-channels. The results demonstrate that at a steering angle of 80°, the PSLL is improved by 2.18, 2.81, and 3.59 dB, respectively, compared to the conventional genetic algorithm (GA). Notably, for a 256-channel array, the PSLL can be optimized to an impressive -18.46 dB using this method. To our knowledge, this represents the lowest PSLL achieved for an equivalent number of channels. Our research offers valuable insights for the practical implementation of OPAs as transmitters in chip-scale frequency modulated continuous wave (FMCW) light detection and ranging (LiDAR) systems.

Aperture Efficiency of Non-Uniform Antenna Arrays With Controlled Sidelobe Level

Aperture Efficiency of Non-Uniform Antenna Arrays With Controlled Sidelobe Level

Design and Analysis of a Non-Uniform Antenna Array for IoT Applications

This letter proposes a mathematical model that allow to analyze the total field irradiated by a non-uniform antenna array, in which the elements consist of different types, with different radiation pattern, positioned and oriented randomly in space. The results obtained are compared with the Multilevel Fast Multipole Method. In the analysis performed, it was observed that both for azimuth and elevation variation the results obtained were significant. Furthermore, the analyzed scenarios are related antennas for internet of things applications, bringing the analysis of the proposed model to practical applications. This analysis can lead to a huge range of applications, depending on interest and necessity, given the possibility of obtaining the radiation pattern formed by a non-uniform antenna array with accurately and with reduced computational resources.

Side lobe level reduction of metasurface transmit array

This paper presents a study on the side-lobe level (SLL) reduction with transmission type metasurface (MTS) using the concept of non-uniform array technique and transmit array antenna. According to the non-uniform antenna array technique, the SLL can be controlled by controlling the amplitude and phase distribution simultaneously. Initially, transmit array concept is used to design the MTS. The radiation characteristics of the MTS antenna are analyzed by exciting with a rectangular patch antenna at a fixed feed position. The simulation results show a gain of 17.6 dB with SLL of −18.3 and −19 dB in ϕ = 0° and 90°-planes, respectively. Later, non-uniform array techniques are used to reduce the SLL by introducing various amplitude distribution functions on the MTS for a fixed focal distance. The MTS incorporates the amplitude tapering functions such as Kaiser, Hamming, Hanning, and Blackman distribution functions. The resulting SLLs are analyzed, and the achieved SLLs are far from the theoretical values. In order to further reduce and control the SLL, the Gaussian distribution function is used, which minimizes the SLL by optimizing the standard deviation(σ). A MTS with 16 × 16 unitcells is fabricated and measured with an optimized σ = 0.31. The measured SLL are −25.1 and −26.3 dB in ϕ = 0° and 90°-planes, respectively.

Nonuniform Antenna Array With Nonsymmetric Feeding Network for 5G Applications

This letter presents a new design of a nonuniform antenna array with low sidelobes for fifth-generation (5G) applications. The proposed design consists of 16 square patch antennas with a corporate beamforming network.The patch antennas are in nonuniform positions within the array aperture, and the corporate beamforming network is composed of nonsymmetric curved microstrip lines to connect the antenna elements. The antenna array is configured to be working from 25.08 to 25.44 GHz. The design process was formulated as a particle swarm optimization to find out the optimum antenna positions for a sidelobe level reduction.Simulated and measurement results reveal the array performance with a sidelobe level reduction of −7.57 dBi compared with a uniform antenna array. The optimized array generates a directivity of 12.03 dBi.

Accuracy Characteristics of the Parametric Burg Method for Spatial Signal Processing in a Nonuniform Array Antenna

Introduction. In the case of a nonuniform (NU) design of the antenna elements (AEs) of the receiving antenna array (AA), the antenna pattern (AP) features sidelobes (SL) with a significantly higher noise level than acceptable values. Under low signal-to-noise ratios (SNR), this noise leads to angular coordinate measuring errors thus worsening the statistical accuracy characteristics (ACs) of the signal. It is of relevance to construct the ACs of angular coordinates when a modified parametric Burg method (BM) is applied to spatial reflected signal processing in a transportable decametre range radar (DRR) with a nonuniform array (NUA) and linear accuracy characteristics. Aim. To analyse the statistical ACs of angular coordinate objects when using a modified BM for spatial reflected signal processing in a DRR with a linear NUA, in which AEs are located with a random step in the range from λ/2 to several λ, where λ is the operating carrier wavelength.Materials and methods. Statistical ACs were constructed by computer modelling in the MatLab software, the reliability of which was confirmed by conventional discrete Fourier transform methods, as well as by comparing the obtained ACs with asymptotic bounds, including Cramer-Rao bounds.Results. The possibility and conditions of using a modified parametric BM for estimating the azimuthal coordinates of reflected radar signals were determined for the case of a nonuniform design of the over-the-horizon DRR receiving AA AEs. Statistical ACs were obtained and compared with the asymptotically optimal ACs of the maximum likelihood estimations corresponding to the uniform AE design.Conclusion. The obtained results confirm the suboptimality of the BM modified for signal processing in the NUA at a random AE spacing step in the range from λ/2 to 2λ, making it applicable for use in transportable DRRs.

A Design Approach of Optical Phased Array with Low Side Lobe Level and Wide Angle Steering Range

In this paper, a new design approach of optical phased array (OPA) with low side lobe level (SLL) and wide angle steering range is proposed. This approach consists of two steps. Firstly, a nonuniform antenna array is designed by optimizing the antenna spacing distribution with particle swarm optimization (PSO). Secondly, on the basis of the optimized antenna spacing distribution, PSO is further used to optimize the phase distribution of the optical antennas when the beam steers for realizing lower SLL. Based on the approach we mentioned, we design a nonuniform OPA which has 1024 optical antennas to achieve the steering range of ±60°. When the beam steering angle is 0°, 20°, 30°, 45° and 60°, the SLL obtained by optimizing phase distribution is −21.35, −18.79, −17.91, −18.46 and −18.51 dB, respectively. This kind of OPA with low SLL and wide angle steering range has broad application prospects in laser communication and lidar system.

Optimization of a Coherent Dual-Beam Array Feed Network for Aperiodic Concentric Ring Antennas

A dual-beam coherent feeding system design approach with a non-uniform layout on a concentric ring array is described and synthesized. In this case, the feeding system is based on a reconfigurable topology composed of a set of alternated power dividers and combiners, providing coherent in-phase outputs. Thus, in this paper, a two-beam architecture based on a coherent feeding system formed by a set of intercalated input signals feeding each circular ring in a non-uniform antenna array with multi-beam shaping and steering features is analyzed. The task of optimizing the aperiodic layout on the shared aperture based on the radii of the circular rings is realized by the differential evolution method. Numerical experiments grounded in antenna synthesis validate the capabilities and improved performance of the proposed dual-beam configuration with a non-uniform layout in contrast with its uniform counterpart, with enhanced performance on average by up to −6.1 dB for sidelobe level and 3.5 dB for directivity. Additionally, the results show a significantly less complex two-beam feeding network in contrast with the case of a typical electronically scanned array—in this proposal, each direction of maximum radiation is conformed and scanned with approximately half of the control inputs.

Optimization of Non-uniform Planar Antenna Array Topology in Two-dimensional DOA Estimation

The paper deals with the optimization of the sparse planar antenna array for direction of arrival (DOA) estimation in two dimensions (azimuth and elevation). The optimization algorithm was proposed on the basis of the peak sidelobe level (SLL) and half-power beamwidth (HPBW) parameters. In empirical validation, we have set up a measurement system to test the efficiency of an optimized array configuration. The array was configured using the patch antennas with frequency band 2.4 GHz. In comparison with several popular array configurations, the experimental results show that the proposed antenna array was optimized, and it provided higher accuracy and resolution in two-dimensional (2D) DOA estimation.

Application of Nonuniform Fourier Transform to Solving Ultrasonic Tomography Problems with Antenna Arrays

In ultrasonic tomography that employs the technique of digital focusing with an antenna (DFA), the problem of increasing the inspection performance is inextricably linked with the problem of increasing the speed of producing synthesized images. This problem can be effectively solved by concurrently using several approaches aimed at increasing the image production speed. In the framework of this paper, we consider the algorithm of nonuniform fast Fourier transform (NUFFT). The NUFFT can be used in the existing computationally efficient spatiotemporal processing algorithms with calculations in the frequency domain and is capable of correctly reconstructing synthesized images with sparse and non-uniform antenna arrays (AAs). The experimental data obtained indicate the ability of the NUFFT-based algorithm to restore synthesized images with high resolution.

Orthogonal Projection-Based Channel Estimation for Multi-Panel Millimeter Wave MIMO

Multi-panel MIMO is a promising technology in millimeter wave communications. Due to its partially hybrid structure and non-uniform antenna array, existing channel estimation cannot be directly applied to multi-panel MIMO. In this paper, we study channel estimation for multi-panel mmWave MIMO. We firstly model channel estimation of multi-panel MIMO as a block-sparse signal recovery problem. Then, according to maximum likelihood criterion, we propose an orthogonal projection method to firstly detect the support of the sparse channel response vector and then perform least square estimation, based on which we also propose a low-complexity greedy support detection in order to reduce computational complexity. Finally, through analyzing pairwise error probability of support detection, we verify the performance gain of joint multi-panel channel estimation over single panel channel estimation, and we further find that joint multi-panel channel estimation with independently generated random combining matrices outperforms that with identically generated combining matrices. Numerical results verify the superiority of our proposed joint multi-panel orthogonal projection based channel estimation over existing schemes.

Position-only synthesis of uniformly excited elliptical antenna arrays with minimum element spacing constraint

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.

Design of Non-Uniform Antenna Arrays for Improved Near-Field MultiFocusing

An extended method for Near-Field Multifocusing on antenna arrays, including the optimization of the locations for the elements of the array, is proposed. Multifocusing is gaining attention in recent years due to the growth of applications such as Internet of Things, or 5G, where a wireless link between a number of sensors and devices must be established, and energy or interference must be managed efficiently. Multifocusing requirements may be addressed by optimizing the feeding weights that must be applied to the elements of an array, but the proposed methodology also optimizes their locations, increasing the degrees of freedom by allowing a non-uniform structure for the array, leading to more efficient structures or better compliance with the specifications. Some experiments are presented to validate the method, showing that it is able to determine the weights and mesh of the array to fulfill the requirements, both obtaining an arbitrary distribution of elements or following a predefined geometric model.

Directive planar antenna array fed by dielectric waveguide for WiFi applications

AbstractA 1‐D nonuniform antenna array fed by a dielectric waveguide operating at 5.7 GHz is proposed. Based on the electromagnetic coupling between the inside travelling wave and the antenna elements, a broadside directive radiation pattern is obtained. The presence of a ground plane allows wall mounting, which is advantageous in many wireless fidelity applications. A prototype was built and measured to prove the concept. The measured −6 dB bandwidth is ca. 150 MHz and the measured realized gain is 9.58 dBi in the broadside direction. This is a very reasonable performance for an extremely simple structure, without feeding network, which is easily manufactured with cheap mass‐production Printed Circuit Board technology.

Linear nonuniform antenna array of planar elements fed by a dielectric waveguide

AbstractA nonuniform antenna array topology fed by a dielectric strip waveguide is proposed for in‐house X‐band radar and localization purposes. It can largely avoid the conductor losses from a traditional feeding network, and also provides a very simple topology that can be easily manufactured with cheap mass‐production Printed Circuit Board technology. The working mechanism is fully based on the electromagnetic coupling between the wave travelling in the dielectric waveguide and the nonuniform antenna elements positioned in series along the waveguide. The antenna elements are optimized in such a way that each element radiates the required power to provide a medium gain broadside beam. A bandwidth of about 160 MHz, a gain of 8.51 dB, and an efficiency of about 86% are obtained for the realized prototype.

Antenna Design by an Adaptive Variable Differential Artificial Bee Colony Algorithm

Optimal design of antennas is very useful to attain narrow beam and low sidelobe, while keeping a low manufacturing cost. Artificial bee colony (ABC) algorithm has shown good performance in solving electromagnetic inverse problems. However, the ABC algorithm costs too much number of iterations and converges slowly in the antenna design. This paper proposes an adaptive variable differential method for ABC (AVDABC). This method adaptively decides the number of decision variables to be mutated. Existing modified ABC algorithms employ the same search equation in one iteration. The proposed adaptive variable method assigns different search equations to chosen decision variables in one iteration. The proposed AVDABC algorithm is more diverse than the existing ABC algorithms. Through numerical simulation on mathematical functions, AVDABC converges faster than three compared algorithms. Moreover, demonstrated by the design of sparse nonuniform antenna array and Yagi-Uda antenna, the AVDABC algorithm achieves promising performance. Thus, the proposed algorithm is helpful to solve antenna array design problems.

Nonuniform antenna array design by parallelizing three-parent crossover genetic algorithm

Antenna plays a very important role in wireless communication. Array elements laid out nonuniformly could achieve better frequency reliability and lower sidelobe level than uniform spaced elements. Designing desirable nonuniform antenna array requires the tuning of distances between each element, excitation, amplitude, and so on. Such design problem can be solved by genetic algorithm. Based on a recently genetic algorithm modification, this paper attempts to invent a parallel framework to enhance the efficiency of genetic algorithm. The parallel framework increases exploitation search of genetic algorithm. The effectiveness of the proposed algorithm is firstly demonstrated on toy problems with different kinds of problem complexity. The proposed algorithm is then verified on nonuniform antenna array design. Compared with genetic algorithm without parallelization, the novel algorithm attains better design solution and saves a lot computation time.

Design of a Microstrip Series Power Divider for Sequentially Rotated Nonuniform Antenna Array

This paper deals with the design of a microstrip series power divider for circularly polarized sequential rotational antenna array. The theoretical description of the design is firstly proposed, comprising the cases of nonuniform weighted antenna arrays. A more flexible open octagon shape instead of the classical open ring is suggested, highlighting benefits in the case of nonuniform power distribution. A design example of an ultra-high frequency (UHF) band 4×4 sequentially rotated Tschebischeff antenna array finally demonstrates the effectiveness of the proposed implementation.

Design of UAVs-Based 3D Antenna Arrays for a Maximum Performance in Terms of Directivity and SLL

This paper presents a design of UAVs-based 3D antenna arrays for a maximum performance in terms of directivity and side lobe level (SLL). This paper illustrates how to model the UAVs formation flight using 3D nonuniform antenna arrays. This design of 3D antenna arrays considers the optimization of the positions of the antenna elements to model the UAVs formation flight. In this case, a disk patch antenna is chosen to be used as element in each UAV. The disk patch antenna is formulated by the well-known cavity model. The synthesis process is carried out by the method of Differential Evolution for Multiobjective Optimization (DEMO). Furthermore, a comparison of the performance of 3D nonuniform antenna arrays is provided with respect to the most conventional arrays (circular, planar, linear, and the cubic) for UAVs formation flight.

Printed nonuniform antenna array for WI‐FI sectorized communications

ABSTRACTWireless networks have joined to the sports venues, offering to the public a set of facilities, such as the access to email, news, and also to use the social networking, uploading their photos. New challenges have emerged to provide Wi‐Fi in this densely populated stadiums, such as increasing capacity and coverage. In this article, an access point antenna array to cover a sector of a stadium is presented. Its structure, designed in a low cost material allows to reduce the total manufacturing costs, an important factor due to the large number of antennas required in these venues. The material characteristic, the broad bandwidth of operation (300 MHz), along with to the low side lobe levels, important to reduce interference between sectors, makes this antenna well‐positioned for wireless communications in these particular locals. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:2037–2041, 2015