Large Antenna Arrays Research Articles

Near-Field Wideband Beamforming for Extremely Large Antenna Arrays

Near-Field Wideband Beamforming for Extremely Large Antenna Arrays

Wavefront Transformation-Based Near-Field Channel Prediction for Extremely Large Antenna Array With Mobility

Wavefront Transformation-Based Near-Field Channel Prediction for Extremely Large Antenna Array With Mobility

Smart Transfer Planer with Multiple Antenna Arrays to Enhance Low Earth Orbit Satellite Communication Ground Links

In this study, we propose a smart transfer planer equipped with multiple antenna arrays to improve ground links for low Earth orbit (LEO) satellite communication. The STP features a symmetrical structure and is strategically placed on both ends of a window, serving both indoor and outdoor environments. Using the window glass as a medium, energy transmission occurs through a coupling mechanism between the planers. The design focuses on large array antenna design, beamforming networks, and coupler design on both sides of the glass. Beamforming networks enable the indoor and outdoor antenna arrays to switch beams in various directions, optimizing high-gain antennas with narrow beamwidths. Through electromagnetic induction and filter couplers, a robust signal transmission channel is established between indoor and outdoor environments. This setup significantly enhances communication efficiency, particularly in non-line-of-sight environments.

Near-Field Codebook Design for Extremely Large Cylindrical Antenna Array Systems

Near-Field Codebook Design for Extremely Large Cylindrical Antenna Array Systems

A Complementary Overview and Challenges in Radar Cross Section Modeling of Phased Array Antennas

The radar cross-section (RCS) is a critical factor in the design and performance of modern airborne weapon systems. These systems utilize phased array antennas due to their low profile, advanced beamforming, and angle measurement capabilities. The effect of phased array antennas on platform RCS can be crucial. Addressing the RCS of phased array antennas involves solving both structural and antenna mode scattering. Each component presents different challenges for computation and requires specific RCS reduction techniques. This short review delves into various existing methods for computing antenna and structural mode RCS and offers insights into their application. Simulating the RCS of large array antennas presents significant challenges due to the high demands on computing resources. Additionally, this review highlights existing solutions aimed at reducing the simulation times and memory usage in RCS modeling while maintaining accurate results. However, further advancements are necessary to simulate large scale array antennas more efficiently and accurately.

High-resolution 2D-DoA sequential algorithm of azimuth and elevation estimation in automotive distributed system of coherent MIMO radars

Objectives. One of the main tasks of radiolocation involves the problem of increasing spatial resolution of the targets in the case of limited aperture of the radar antenna array and short length of time samples (snapshots). Algorithms must be developed to provide high angular resolution and low computational complexity. In order to conform with the existing Advanced Driver Assistance Systems requirements, modern cars are equipped with more than one radar having a common signal processing scheme to improve performance during target detection, positioning, and recognition as compared to a single radar. The present study aims to develop a two-dimensional Direction-of-Arrival algorithm with low computation complexity as part of distributed coherent automotive radar system for cases involving short time samples (snapshots).Methods. A virtual antenna array formation algorithm is formulated according to the two-dimensional Capon method. A proposed modification of two-dimensional Capon algorithm is based on sequentially estimating the directions of arrival for the distributed radar system. The Monte Carlo method is used to compare the effectiveness of the considered algorithms.Results. The 2D-DoA sequential algorithm of azimuth and elevation estimation is proposed. The comparative analysis results for the developed algorithm and classical 2D Capon method based on numerical simulation using Monte Carlo method are presented. The proposed scheme of DoA estimation for coherent signal processing of distributed radars is shown to lead to an improvement of the main considered metrics representing the probability of correctly estimating the number of targets, mean square error, and square error compared to a single radar system. The proposed low-computational algorithm shows the gain in complexity compared to full 2D Capon algorithm.Conclusions. The proposed two-stage algorithm for estimating the directions of arrival of signals in azimuth and elevation planes can be applied to the distributed system of coherent radars with several receiving and transmitting antennas representing multiple input multiple output (MIMO) radars. The algorithm is based on sequentially estimating the directions of arrival, implying estimation in the azimuthal plane at the first stage and estimation in the vertical plane at the second stage. The performance of a coherent radar system with limited antenna array configuration of separate radar is close in characteristics to a high-performance 4D-radar with a large antenna array system.

A decentralized HC-ADMM approach for large antenna arrays

This work addresses the evolving landscape of internet of things (IoT) applications and large antenna array systems, where optimizing spectral efficiency and simplifying design complexities are crucial. Focusing on two key challenges, the study introduces a novel hybrid analog-digital transceiver strategy tailored for frequency-selective channels. By integrating Shannon and Hartley theorems, the approach enhances data transfer rates, thereby optimizing radio frequency (RF) chain utilization in large-scale antennas. To achieve a balance between transceiver performance and hardware complexity, the study employs a decentralized alternating direction method of multipliers (ADMM) framework. The proposed hybrid consensus ADMM algorithm (HC-ADMM) ensures efficient convergence in decentralized optimization scenarios. Comparative analyses with ADMM and existing system transceiver optimization (ESTO) models highlight HC-ADMM's superior performance across key metrics such as spectral efficiency, efficiency per cell, total efficiency, and optimal scheduling of user equipment (UEs). Particularly notable is HC-ADMM's advanced optimization capabilities as the number of transmit antennas increases, positioning it as a promising approach for enhancing overall communication network performance.

Low sidelobe planar electrically large sparse array antenna with element number reduction based on genetic algorithm

AbstractConventionally, both electrically larger (EL) arrays and sparse arrays offer the advantage of element number reduction but disadvantage of high sidelobe levels. A new scheme of planar EL sparse array antenna based on a genetic algorithm (GA) to achieve low sidelobe with element number reduction is proposed. To begin with, EL sparse array antenna optimisation models based on GA for both linear and planar arrays are analysed. Then, an EL slot antenna element based on a 3 × 3 substrate integrated waveguide cavity is designed. An 8‐element linear EL sparse array antenna is designed and compared with a uniform array antenna, demonstrating a reduction in the maximum sidelobe level (MSLL) by nearly 4.6 dB. After that, a 4 × 8 element planar EL sparse array antenna is fabricated and measured. Compared to an 8 × 16 element planar EL uniform array antenna, the number of antenna elements is reduced by 75%, while the MSLL is reduced by approximately 3 dB. The measured −10 dB impedance bandwidth ranges from 25.3 to 27.8 GHz. At the central frequency, the radiation pattern achieves a peak gain of 29.6 dBi, exhibiting low sidelobe levels below −15.0 dB.

TransientX: A high-performance single-pulse search package

Context. Radio interferometers composed of a large array of small antennas possess large fields of view, coupled with high sensitivities. For example, the Karoo Array Telescope (MeerKAT) achieves a gain of up to 2.8 KJy−1 across its >1 deg2 field of view. This capability significantly enhances the survey speed for pulsars and fast transients. It also introduces challenges related to the high data rate, which reaches a few Tb s−1 for MeerKAT, and it requires substantial computing power. Aims. To handle the high data rate of surveys, we have developed a high-performance single-pulse search software called “TransientX”. This software integrates multiple processes into one pipeline, which includes radio-frequency interference mitigation, dedispersion, matched filtering, clustering, and candidate plotting. Methods. In TRANSIENTX, we developed an efficient CPU-based dedispersion implementation using the sub-band dedispersion algorithm. Additionally, TRANSIENTX employs the density-based spatial clustering of applications with noise (DBSCAN) algorithm to eliminate duplicate candidates, using an efficient implementation based on the kd-tree data structure. We also calculate the decrease of signal-to-noise ratio (s/N) resulting from dispersion measure, boxcar width, spectral index, and pulse-shape mismatches. Remarkably, we find that the decrease of S/N resulting from the mismatch between a boxcar-shaped template and a Gaussian-shaped pulse with scattering remains relatively small, at approximately 9%, even when the scattering timescale is ten times that of the pulse width. Additionally, the decrease in the S/N resulting from the spectral index mismatch becomes significant with multi-octave receivers. Results. We have benchmarked the individual processes, including dedispersion, matched filtering, and clustering. Our dedispersion implementation can be executed in real time using a single CPU core on data with 4096 dispersion measure trials, which consist of 4096 channels and have a time resolution of 153 µs. Overall, TRANSIENTX offers the capability for efficient CPU-only real-time single-pulse searching.

On the Use of Near-Field Constellation Focusing for Physical Layer Security with Extremely Large Antenna Arrays

In the fast-changing world of wireless communications, the combination of extremely large antenna arrays (ELAAs) and energy-efficient transmission methods is envisioned for the 6G. The application of directivity in the transmitted constellation can increase physical layer security (PLS) and promote the energy efficiency of transmission. In such scenarios, large constellations can be divided into multiple binary phase shift keying (BPSK) components, with each component being individually amplified and transmitted by an antenna. In this work, we consider an ELAA acting as a transmitter and constellation decomposition at the sub-array level. We investigate the impact of considering a near-field channel model in terms of secrecy rate and mutual information. In addition to the energy efficiency of the constellation decomposition, it is demonstrated that the particularities of near-field beamforming increase the PLS, namely in terms of robustness to eavesdropping.

Grid-Free MIMO Beam Alignment Through Site-Specific Deep Learning

Beam alignment is a critical bottleneck in millimeter wave communication. An ideal beam alignment technique should achieve high beamforming gain with low latency, scale well to systems with higher carrier frequencies, larger antenna arrays and multiple user equipments, and not require hard-to-obtain context information. These qualities are collectively lacking in existing methods. We depart from the conventional codebook-based (CB) approach where the optimal beam is chosen from quantized codebooks and instead propose a grid-free beam alignment method that directly synthesizes the transmit and receive beams from the continuous search space using measurements from a few site-specific probing beams found via a deep learning pipeline. In realistic settings, the proposed method achieves a far superior signal-to-noise ratio (SNR)-latency trade-off compared to the CB baselines: it aligns near-optimal beams 100x faster or equivalently finds beams with 10-15 dB higher average SNR in the same number of searches, relative to an exhaustive search over a conventional codebook.

Coverage performance of cooperative NOMA MmWave networks with wireless power transfer

The millimeter-wave (mmWave) plays a vital role in the fifth generation (5G) and beyond-5G (B5G) cellular networks, which is also attractive for wireless power transfer (WPT) since the mmWave base stations (BSs) are usually equipped with large antenna arrays. This paper studies a wireless-powered mmWave communication system with non-orthogonal multiple access (NOMA) cooperative transmission. In this system, the BS intends to transmit signals to a near-wireless device (WD) and a far-WD simultaneously, where the location of near-WD is fixed that can be treated as a relay for cooperatively transferring the signal to a far-WD, which is far away from the BS. Since there are multiple far-WDs in the region, two pairing schemes based on the distance between the near and far WDs are investigated, i.e., 1) near-WD pairs with the nearest far-WD (NNF); 2) near-WD pairs with a randomly selected far-WD (NRF). We evaluate the downlink transmission performance by assuming that the near-WD is energy-constrained and performs cooperative transmission after scavenging sufficient radio frequency (RF) energy while successfully decoding both the signals for near-WD and far-WD. Since the near-WD may accumulate sufficient energy in several transmission blocks, the processes of charging and discharging are analyzed by a finite-state Markov chain. On this basis, the performance of two WD pairing schemes is analyzed by deriving the exact expressions of coverage probabilities for both the near-WD and far-WD. The simulation results show that the considered mmWave cooperative communication system with NOMA schemes can achieve a better coverage performance than the compared OMA and other schemes, while the coverage probability of far-WD with the NNF pairing scheme is better than that with the NRF pairing scheme.

Low Complexity Radio Frequency Interference Mitigation for Radio Astronomy Using Large Antenna Array

With the ongoing growth in radio communications, there is an increased contamination of radio astronomical source data, which hinders the study of celestial radio sources. In many cases, fast mitigation of strong radio frequency interference (RFI) is valuable for studying short lived radio transients so that the astronomers can perform detailed observations of celestial radio sources. The standard method to manually excise contaminated blocks in time and frequency makes the removed data useless for radio astronomy analyses. This motivates the need for better RFI mitigation techniques for array of size M antennas. Although many solutions for mitigating strong RFI improves the quality of the final celestial source signal, many standard approaches require all the eigenvalues of the spatial covariance matrix ([Formula: see text]) of the received signal, which has [Formula: see text] computation complexity for removing RFI of size d where [Formula: see text]. In this work, we investigate two approaches for RFI mitigation, (1) the computationally efficient Lanczos method based on the Quadratic Mean to Arithmetic Mean (QMAM) approach using information from previously-collected data under similar radio-sky-conditions, and (2) an approach using a celestial source as a reference for RFI mitigation. QMAM uses the Lanczos method for finding the Rayleigh–Ritz values of the covariance matrix [Formula: see text], thus, reducing the computational complexity of the overall approach to [Formula: see text]. Our numerical results, using data from the radio observatory Long Wavelength Array (LWA-1), demonstrate the effectiveness of both proposed approaches to remove strong RFI, with the QMAM-based approach still being computationally efficient.

Fading in Reflective and Heavily Shadowed Industrial Environments With Large Antenna Arrays

Fading in Reflective and Heavily Shadowed Industrial Environments With Large Antenna Arrays

On the Imaging of Large Antenna Array Navigation Systems

On the Imaging of Large Antenna Array Navigation Systems

Deriving Mutual Impedance Matrix of a Large Antenna Array from Embedded Element Patterns with Measurement Noise

Deriving Mutual Impedance Matrix of a Large Antenna Array from Embedded Element Patterns with Measurement Noise

Active RIS-Assisted Sup-Degree of Freedom Interference Suppression for a Large Antenna Array: A Deep-Learning Approach With Location Awareness

Active RIS-Assisted Sup-Degree of Freedom Interference Suppression for a Large Antenna Array: A Deep-Learning Approach With Location Awareness

Shaping Radiation with Line Source Antenna for Ramp Pattern Generation

Array antennas are essential in communication technology because they can produce focused beams of electromagnetic radiation that can be precisely shaped and directed for various applications. These antennas typically generate a radiation pattern with a primary lobe, the main beam, accompanied by smaller minor lobes. The size and distribution of these lobes depend on the array's design and configuration. For large array antennas, the main beam becomes extremely narrow, enabling precise point-to-point communication over long distances. This precision is especially beneficial for applications requiring accurate targeting or transmission to specific locations. However, achieving such optimized performance requires careful design and engineering. This study, builds on Woodward's amplitude control method, initially developed for generating sector beams, to create ramp patterns with unique applications in antenna engineering. By adjusting the amplitudes of the signals fed into each element of the array, the researchers can shape the resulting radiation pattern to meet specific requirements. The paper provides detailed analysis and computational data demonstrating the effectiveness of this approach in achieving the desired beam patterns. These results offer valuable insights into antenna design and optimization, potentially advancements in wireless communication, radar systems, and satellite communication.

Metasurface-based bandwidth and isolation enhancement for compact H-plane coupled antennas

A simple metasurface (MS) composed of a square metal ring and four extended metal strips is designed to simultaneously enhance the bandwidth and isolation of H-plane coupled microstrip patch antenna array in this paper. By adding the MS above the patch array, a new resonance is formed to increase the working bandwidth and the coupling between the antenna array is largely depressed to enhance the isolation property. An antenna array with MS is simulated, fabricated and measured. The simulated and measured results are in good agreements. Measured results indicate that the bandwidth with S 11 ⩽ −10 dB is broadened by 8.1% compared with the original coupled antennas. In addition, within the working band, the isolation level is better than −20 dB, and the maximum mutual coupling reduction reaches 39.6 dB at 5.19 GHz, performing an excellent wideband decoupling effect. Moreover, the proposed method has been extended to large antenna arrays, implying that it can be widely used in multiple-input multiple-output or the wireless Rx/Tx system.

Hybrid control of attitude maneuver and structural vibration for a large phased array antenna satellite

This paper focuses on the study about hybrid control strategy of attitude maneuver and structural vibration for a large phased array antenna satellite. The satellite system is equipped with cable actuators in the antenna structure and control moment gyros on the central satellite. Firstly, the rigid-flexible coupling dynamic model of the entire satellite system is established based on the hybrid coordinate method. Then a control strategy is presented which could realize the ideal attitude maneuver of satellite while suppressing the structural vibration simultaneously. The proposed strategy is contained of two parts: the attitude controller is designed based on the computed torque method, and the vibration controller is achieved by using a piecewise cost function which could ensure the unidirectional and saturated constraints of cable actuators. Finally, numerical simulations of a large antenna satellite model demonstrate that the structural vibration during the attitude maneuver process can be suppressed effectively by applying the proposed control strategy.