Two-dimensional Antenna Array Research Articles

Investigation of Planar Isolators for Mutual Coupling Reduction in Two-Dimensional Microstrip Antenna Arrays

The design of isolators to reduce mutual coupling in large two-dimensional antenna arrays is complex and requires significant computational effort. This work attempts to alleviate this problem by applying different types of planar isolators in different orientations and experimenting first with two-element microstrip antenna arrays. A U-shaped planar transmission line isolator, a U-shaped planar transmission line-based destructive ground structure, and a planar neutralization line structure are designed to reduce E-plane or H-plane coupling in two-element microstrip antenna arrays. A mutual coupling reduction of approximately 6 dB is achieved. Four combinations of these planar isolators are compared and analyzed in a four-element microstrip antenna array. An optimal combination is then obtained by using two reversely placed U-shaped line isolators, which reduce the mutual coupling by more than 6.1 dB. The study is also extended to a 5 × 5 antenna array. Similar results of mutual coupling reduction are obtained. In addition to simulation, both two-element and 25-element microstrip antennas have been constructed and tested. The agreement of the simulation results with the measured results confirms the effectiveness of the decoupling structures.

Two-dimensional Sparse Antenna Array of a Passive Coherent Radar using a Parametric Algorithm of Signal Processing via the Section Method

Introduction. A two-dimensional configuration of the receiving antenna array (AA) is used to measure the angular coordinates of radar targets – azimuth and elevation. A transformation of one-dimensional uniform AA into a flat two-dimensional AA with a fixed number of antenna elements (AEs) and constant aperture size leads to a nonuniform arrangement of AE in the AA rows. As a result, the AA becomes sparse, which negatively affects the quality of the AA three-dimensional antenna pattern (AP). The section method based on the modified parametric Burg algorithm is a promising and relevant method for constructing directional characteristics. This method can be recommended for spatial processing of reflected signals in a passive coherent radar with a two-dimensional sparse receiving AA.Aim. To analyze the azimuthal and elevation sections of three-dimensional APs obtained using a modified Burg method for spatial processing of reflected signals in a passive coherent radar, the AEs of which are located horizontally and vertically with a step that is a multiple of the half the wavelength λ of the used illumination signal carrier oscillation.Materials and methods. The construction of directional characteristics was implemented via computer simulation in the MATLAB environment with the effect of uncorrelated additive complex normal noise on the receiving channels in each AE as an interference.Results. The possibility and conditions for the application of the modified parametric Burg method in the problems of single signal detecting and angular resolution of equal-power signals in a passive coherent radar, which includes a two-dimensional sparse AA, were determined. The obtained Burg method directional characteristics were compared with the directional characteristics obtained using conventional algorithms based on the discrete Fourier transform. The use of the Burg method allowed the AP side lobe level to be reduced to a practically acceptable level of -12 ... -17 dB at a signal to noise ratio 6 dB. In addition, the Rayleigh resolution of signals in the AA was significantly improved.Conclusion. The presented modified Burg method is suitable for signal processing in two-dimensional sparse AA, subject to restrictions on the AE placing method and the AA aperture size. This allows the Burg method to be recommended for use in passive coherent radars.

Time-Space Dimension Reduction of Millimeter-Wave Radar Point-Clouds for Smart-Home Hand-Gesture Recognition

This paper proposes a novel time-space dimension reduction method for millimeter-wave radar point-clouds on long-distance or large-field-of-view hand-gesture recognition. First, a two-dimensional antenna array is used to obtain radar point-clouds composed of range, Doppler, azimuth, elevation, and amplitude. The point-cloud time series are further reduced in dimensionality to reconstruct radar spectrums with less interference and better time-space continuity in the Range-Doppler-Azimuth-Elevation (RDAE) domain, and generate new spatial position spectrums after transforming to the three-dimensional cartesian coordinate system, which are superior to radar spectrums in the RDAE domain in terms of space invariance. Then a spatial position alignment method is proposed to improve the spatial consistency of multi-position dataset. Finally, a multi-channel convolutional neural network is designed for multi-position hand-gesture recognition. Experimental results show that the proposed method can solve the problems of poor space invariance in the RDAE domain and poor generalization performance for different spatial positions and different users in existing methods. For hand-gesture recognition within a long distance of 3 meters and a large field-of-view of 60 degrees, the average classification accuracies of 5 waving hand-gestures collected at multiple positions for trained user A, non-trained user B, and non-trained user C can reach 99.7%, 91.1%, and 87.1%, respectively.

Synchrotron radiation transmission by two coupled flat microchannel plates: new opportunities to control the focal spot characteristics.

An improved theoretical model to calculate the focal spot properties of coherent synchrotron radiation (SR) soft X-ray beams by combining and aligning two microchannel plates (MCPs) is presented. The diffraction patterns of the radiation behind the MCP system are simulated in the framework of the electrodynamical model of the radiation emission from two-dimensional finite antenna arrays. Simulations show that this particular optical device focuses the soft X-ray radiation in a circular central spot with a radius of ∼4 µm. The study points out that such MCP-based devices may achieve micrometre and sub-micrometre spot sizes as required by many applications in the soft X-ray range. Finally, based on experimental and theoretical results of the radiation transmission by this MCP-based device, a new method to characterize the spatial properties of brilliant SR sources is discussed.

Angular Resolution of Closely Spaced Signal Sources Using a Two-Dimensional Antenna Array on the Basis of the Minimum-Polynomial Method

Angular Resolution of Closely Spaced Signal Sources Using a Two-Dimensional Antenna Array on the Basis of the Minimum-Polynomial Method

Large-scale true-time-delay remote beamforming with EO frequency combs and multicore fiber.

Optical true-time-delay (OTTD) beamforming is a promising solution to support the ultra-broadband radio access network. However, large-scale antenna arrays set at remote radio units require the OTTD counterpart to have corresponding larger-scale channel numbers. Here, we demonstrate an OTTD remote beamforming network with a record 287 channel number using electro-optic frequency combs and multicore fiber. Our proposed scheme can generate beams for both one-dimensional and two-dimensional antenna arrays. We highlight that using multicore fiber not only increases the channel numbers but also supports remote beamforming. We estimate the long-term stability of this remote beamforming network, and 1-ps-level relative time delay variation in 2 h is obtained when using multicore fiber. It is one order of magnitude better than using parallel single-mode fibers. Thus, highly stable beamforming is achieved. These results pave the way for the application of OTTD beamforming in 5G and beyond networks.

Dual-Polarized Two-Dimensional Multibeam Antenna Array With Hybrid Beamforming and its Planarization

A feeding network crossing method is proposed to form an N $\times $ N dual-polarized two-dimensional multibeam antenna array (2D-MBAA) with analog-digital hybrid beamforming, which solves the problem of needing additional connection structure between the dual-polarized antenna array and analog feeding network for large-scale antenna arrays. The main design work is focused on the analog-beamformer (ABF) and two structures are proposed. One is vertical-crossed (VC) ABF and the other is parallel-crossed (PC) ABF, and the latter is a more complex design in exchange for a significantly reduced profile. As a verification, a $4\times 4$ dual-polarized 2D-MBAA with PC-ABF has been fabricated and tested. It is operated at 3.45GHz with a bandwidth of about 10%, and it can realize a scanning angle of ±45°.

Precise Angle Estimation by Jointly Using Spatial/Temporal Change of Channel State Information and Its Application in Pedestrian Positioning

Previously, we have proposed a pedestrian positioning method that uses vehicles near a pedestrian as anchors, and combines vehicle-to-vehicle (V2V) communication signals and GPS signals for high precision positioning. In this method, pedestrian-vehicle distance and angle of arrival (AoA) are estimated from the channel state information (CSI) of vehicular signals and used in position computation, but the precision of angle estimation is limited due to the small number of antennas that can be mounted on a mobile device. To solve this problem, in this paper, we propose a new method to estimate AoA precisely by jointly using spatial change of CSI at multiple antennas and temporal change of CSI per antenna (caused by pedestrian/vehicle movement), and on this basis improve pedestrian positioning precision. Specifically, a two-dimensional antenna array is constructed from CSI acquired from multiple antennas/timings, and the MUSIC method with spatial smoothing is applied to estimate AoA. 3D ray tracing simulations with real 3D map confirm that the proposed method can effectively improve the precision of angle estimation and reduce positioning error when only a small number of antennas are available at a pedestrian device, and the performance increases with the number of antennas.

Compressive-Sensing-Aided MIMO Radar Enabling Multi-Functional and Compact Sensors in Air Scenarios Using Optimized Antenna Arrays

We address the problem of direction-of-arrival (DoA) estimation for air targets using a compact, multi-functional radar sensor. In order to enhance the angular resolution of such sensors while exploiting the sparseness of typical air scenarios, we consider the combination of a multiple-input multiple-output (MIMO) radar approach with suitable compressive-sensing (CS) techniques. In particular, we investigate the combination of MIMO processing for two-dimensional (2D) antenna arrays with CS-based angular processing for three-dimensional (3D) target localization and 2D DoA estimation in azimuth and elevation. We analyze the benefits of randomized antenna element positions in one and two dimensions and devise optimized array geometries for practicable aperture sizes. In particular, we take physical side constraints into account, such as the smallest realizable/ desired element spacing as well as area restrictions for antenna placement within the overall aperture. The aperture area reserved by this means could be used to accommodate additional hardware components enabling a multi-functional sensor approach. Extensive computer simulation results for different 3D target scenarios illustrate the advantages of our CS-based compact MIMO radar approach with randomized antenna elements compared to fully randomized arrays, given the same number of physical antenna elements.

Angular Resolution of Closely Spaced Signal Sources Using a Two-Dimensional Antenna Array Based on the Minimum-Polynomial Method

Angular Resolution of Closely Spaced Signal Sources Using a Two-Dimensional Antenna Array Based on the Minimum-Polynomial Method

Spatial Interference Reduction by Subarray Stacking in Large Two-Dimensional Antenna Arrays

This article proposes a systematic approach for stacking uniform linear arrays (ULAs) of different sizes to reduce sidelobes and form nulls to the radiated beam pattern. In sidelobe reduction, the nulls and sidelobes of the vertically stacked ULAs are aligned to reduce the overall sidelobe level (SLL). In nulling, the nulls of varying length ULAs are aligned to configure the null direction and simultaneously reduce the sidelobes. Both approaches are relaxed to ensure the feasibility of the implementation. The stacking methods are studied by an extensive set of simulations together with azimuth and elevation beamforming. A sidelobe reduction method showed potential for better than 30 dB SLL and more than 20 dB relative null depth with less than 100 antenna elements. Finally, the concepts are validated by beam pattern measurements of a 28 GHz 64-element, 16-chain phased-array transceiver using a 100 MHz wide 5G waveform.

Synthesis of two-dimensional antenna arrays by the method of generalized separation of variables

Synthesis of two-dimensional antenna arrays by the method of generalized separation of variables

Two-Dimensional Periodic Dual-Polarized Over Wave Region Antenna Array

The two-dimensional periodic dual-polarized antenna array in the form of a nonuniform multiconductor line of square cross-section conductors is proposed and studied. Using the approximate theory, matching characteristics of the two-conductor line with three different laws of impedance variation are studied and the optimum law is found. Electrodynamic modeling of an infinite two-dimensional periodic array of these elements is carried out using the finite element method at different scanning modes. Using a numerical experiment, the possibility of implementing the over wave region matching mode is demonstrated for arrays of 144 (12 × 12) and 576 (24 × 24) elements: for the array of 576 elements, the working bandwidth in the cophased mode was 1 : 34; when scanning in the sector of 90°, more than 1 : 15.

Energy and Information Beamforming in Airborne Massive MIMO System for Wireless Powered Communications.

Energy supply and information backhaul are critical problems for wireless sensor networks deployed in remote places with poor infrastructure. To deal with these problems, this paper proposes an airborne massive multiple-input multiple-output (MIMO) system for wireless energy transfer (WET) and information transmission. An air platform (AP) equipped with a two-dimensional rectangular antenna array is employed to broadcast energy and provide wireless access for ground sensors. By exploiting the statistical property of air-terrestrial MIMO channels, the energy and information beamformers are jointly designed to maximize the average received signal-to-interference-plus-noise ratio (SINR), which gives rise to a statistical max-SINR beamforming scheme. The scheme does not rely on the instantaneous channel state information, but still requires large numbers of RF chains at AP. To deal with this problem, a heuristic strongest-path energy and information beamforming scheme is proposed, which can be implemented in the analog-domain with low computational and hardware complexity. The analysis of the relation between the two schemes reveals that, with proper sensor scheduling, the strongest-path beamforming is equivalent to the statistical max-SINR beamforming when the number of AP antennas tends to infinity. Using the asymptotic approximation of average received SINR at AP, the system parameters, including transmit power, number of active antennas of AP and duration of WET phase, are optimized jointly to maximize the system energy efficiency. The simulation results demonstrate that the proposed schemes achieve a good tradeoff between system performance and complexity.

Fair Downlink Transmission for Multi-Cell FD-MIMO System Exploiting Statistical CSI

In this letter, we investigate the downlink transmission for multi-cell full-dimension multiple-input multiple-output systems. Two-dimensional large-scale antenna array is deployed at each base station (BS). All cells sharing the same time-frequency resource. Based on a lower bound of the average signal to interference ratio and taking into account the fairness, we propose a downlink transmission scheme exploiting only statistical channel state information (CSI). The proposed scheme requires only a small fraction of users’ statistical CSI to be exchanged between adjacent BSs. Simulation results show that the proposed scheme can achieve good fairness, and high cell-edge and average user rate.

Неэквидистантные двумерные антенные решеткина основе латинских квадратов

Неэквидистантные двумерные антенные решеткина основе латинских квадратов

A SET OF THE SPECIALIZED SOFTWARE FOR ANALYSIS AND SYNTHESIS OF AESA

The issue of expediency of application of in-house specialized software in resolving problems of design of antenna devices is reviewed. The functional capabilities of existing software models of antenna arrays have been analyzed. The application of the developed software in designing a whole set of tasks for the adoption of basic design and engineering solutions at the stage of design of active phased antenna arrays as well as at the state of their upgrade is substantiated. The developed software has an intuitive user-friendly interface adapted to a specific set of tasks. As an example, a description is given of a set of developed software models for the study of equidistant linear and two-dimensional antenna arrays, as well as non-equidistant arrays. The developed set of programs differs from the multi-purpose software of electrodynamic modeling by high speed of preparatory and calculation operations, and the convenience of use.

One- and two-dimensional antenna arrays for microwave wireless power transfer (MWPT) systems and dual-antenna transceivers

ABSTRACTIn this work, we demonstrate novel one-dimensional (1D) and two-dimensional (2D) antenna arrays for both microwave wireless power transfer (MWPT) systems and dual-antenna transceivers. The antenna array can be used as the MWPT receiving antenna of an integrated MWPT and Bluetooth (BLE) communication module (MWPT-BLE module) for smart CNC (computer numerical control) spindle incorporated with the cloud computing system SkyMars. The 2D antenna array has n rows of 1 × m 1D array, and each array is composed of multiple (m) differential feeding antenna elements. Each differential feeding antenna element is a differential feeding structure with a microstrip antenna stripe. The stripe length is shorter than one wavelength to minimise the antenna area and to prevent being excited to a high-order mode. That is, the differential feeding antenna element can suppress the even mode. The mutual coupling between the antenna elements can be suppressed, and the isolation between the receiver and the transmitter can be enhanced. An inclination angle of the main beam aligns with the broadside, and the main beam is further concentrated and shrunk at the elevation direction. Moreover, if more differential feeding antenna elements are used, antenna gain and isolation can be further enhanced. The excellent performance of the proposed antenna arrays indicates that they are suitable for both MWPT systems and dual-antenna transceivers.

Двумерные адаптивные антенные решетки в арифметике комплексных и действительных чисел

Двумерные адаптивные антенные решетки в арифметике комплексных и действительных чисел

Nonequidistant two-dimensional antenna arrays are based on Latin squares for registration of cosmic, atmospheric and lithospheric radiation

The possibility of using Latin squares for constructing two-dimensional non-equidistant antenna arrays that can be used for development of radio telescopes and systems for remote sensing of atmospheric and lithospheric radiation has been shown. An algorithm for calculating the coordinates of elements of a non-equidistant antenna array using the values of elements of Latin squares is proposed. It is shown that in this case, it is possible to obtain an almost complete coverage of the grid of spatial frequencies in the region of the arrangement of the elements at small filling coefficients of array. Directional patterns are studied and the side lobes levels are estimated for non-equidistant antennas obtained on the basis of Latin squares. The possibility of synthesizing of large antenna arrays on the basis of composite squares using the embedding of generative Latin squares is shown. The characteristics of the obtained arrays are studied. It is shown that using the shifts and mutual rotations of individual layers is involved in the synthesized array; its characteristics can be substantially improved.