Antenna Array Elements Research Articles

Efficient DOA Estimation Under Partially Impaired Antenna Array Elements

Partially impaired antenna array is one of the challenges for estimating the accurate directions of the signals impinging upon antenna arrays. It causes random loss of the signal information, resulting in the poor direction of arrival (DOA) estimation performance. In this paper, we propose an efficient DOA estimation method under partially impaired antenna array elements, which work randomly. We first devise a strategy to detect the positions of randomly lost signal information corresponding to partially impaired antenna array elements and then formulate the problem of received signal recovery as low rank matrix completion. Afterwards, we utilize the recursive least squares (RLS) with the nulling antenna array for DOA estimation due to its fast convergence and low mean square error properties and place the nulls in the directions of received signals by adjusting the weight vectors adaptively. The reciprocal of the antenna array defines the output spatial spectrum, and the directions of the signals are estimated by finding the high peaks. We also investigate the mean and mean square performance of the RLS after <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">recovering</i> and <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">de-noising</i> the received signal. Simulation results show that the proposed method converges to optimal solution fast and outperforms the existing DOA estimation methods.

Antenna for 5G Mobile Communication at 28 GHz

Fifth generation (5G) mobile communications has become one of the trendiest issues in recent years, especially in the development of wireless technology for communications. As such, 5G mobile communications will also suffer severe path loss, due to the high frequency bands. This work presents the antennas for 5G mobile communication at 28 GHz on Rogers RT5880 with a dielectric constant, εr of 2.2, loss tangent, tan δ of 0.0009 and thickness, h of 0.787 mm. A rectangular microstrip patch are proposed in this work which consist of a single element and array configurations with two and four elements. Microstrip feed line and inset feed line are implemented to observe their performances. It can be observed from the simulation results that the gain and directivity increase from a single element up until four elements array antenna for both the microstrip feed line and inset feed line of the rectangular microstrip patch antenna. This confirm to the fact that array antenna produces high gain and directivity which could overcome the challenge of high free space path loss in millimeter-wave. The spacing between each element in the array antenna are spaced accordingly and not so close with each other in order to suppress the mutual coupling between the elements. It is shown that the mutual coupling is greatly reduced based on the greater values of reflection coefficient in two-element and four-element array antennas. Based on the gain, directivity and reflection coefficient, inset feed line antennas perform better than microstrip feed line antennas. In terms of dimensions, the size of the antenna with an inset feed line reduces as compared to microstrip feed line as the number of elements increases. Thus, it is safe to conclude that inset feed line antennas outperform microstrip feed line antennas when it comes to gain, directivity, reflection coefficient, and dimensions of antennas. Therefore, the proposed array antennas in this work are suitable to be used in 5G mobile communications.

Simulation Based Poynting Vector Description of the Field Regions for Simple Radiating Structures

Estimating the coupling properties between a radiating structure and other conductive elements, the field behavior of the radiating source is essential to know. One well-known classification of the field behavior are the field-regions around antennas, namely, the far-field, the radiating near-field, and the reactive near-field. The different kinds of near-fields are distinguished by the reactive and radiating parts of the electromagnetic field, whereas in the far-field region the field behaves as a plane wave in the direction of propagation. One way to describe these field characteristics is to use the complex Poynting vector, which defines the electromagnetic power flow. This work presents a Poynting-vector-based approach to classify and visualize the field behavior around simple radiators using numerical simulations. First, the approach is applied to simple antenna structures such as dipoles and loop antennas. Later, the introduced field regions are utilized to predict the coupling behavior of practical applications, the coupling between single elements of a linear antenna array, and the coupling behavior of an electrically large loop antenna. It could be shown that the introduced approach, defining a surface description of the boundary between the near-field regions, enables the possibility of predicting the coupling behavior between radiating structures. The introduced error estimator for the far-field also delivers knowledge about the far-field quality in different angular directions and distances. All simulations have been executed applying a one-dimensional partial element equivalent circuit method.

On the far‐field sampling strategies for reliable Bayesian compressive diagnosis of planar arrays

AbstractDealing with the detection of the faulty elements of planar antenna arrays with a probabilistic Bayesian compressive sensing (BCS) approach, a key asset for the reliable prediction of the actual status of the antenna under test is the sampling strategy to remotely collect the far‐field (FF) data. The aim of this letter is to provide insights into the effectiveness and the reliability of different FF sampling strategies to collect the input data for a state‐of‐the‐art array diagnosis method based on a multitask BCS technique. Representative results are shown to verify the impact of each sampling strategy on the achievable reconstructions.

Method for Calculation of the Interaction of Elements in a Large Convex Quasi-Periodic Phased Antenna Array

Method for Calculation of the Interaction of Elements in a Large Convex Quasi-Periodic Phased Antenna Array

An Irregular Tiled Array Technique for Massive MIMO Systems

An irregular tiled array technique is proposed for the application of massive MIMO systems, where the uniformly spaced antenna array elements are irregularly divided into subarrays fed by only one radio frequency (RF) chain separately. As compared to conventional beamforming architecture, the number of RF chains is reduced to one-half or one-quarter of the original number by using domino-shaped subarrays or tetromino-shaped subarrays, respectively. Two beamforming architectures for such a framework are proposed and a minimum mean square error (MMSE) method is applied to design the layouts of irregular arrays efficiently. In the framework of single-user massive MIMO systems, numerical simulation results show that the proposed architectures outperform conventional beamforming architectures and antenna selection architecture under the same number of RF chains conditions. With saving half of the transceivers, the loss of gain of the state-of-the-art sparsely sampled array is 1.9dB in the broadside and 2.2 dB for scanning to 30° in comparison with reference array (i.e., one transceiver per element). By contrast, there is no loss of gain of domino-shaped irregular array (i.e., one transceiver per two elements) in the broadside as compared to reference array and the loss of gain will be about 1.5dB for scanning to 30°.

Design and Development of MIMO Antenna for Wireless Communications

A high-isolation eight-antenna multi-input multi- output (MIMO) array running in the 3.5 – 3.6 GHz band for future smartphones is proposed. Here, a novel balanced open-slot antenna is designed as an array antenna element, in which this antenna diagram can yield a balanced slot mode (with decreased ground effects) that can enhance the isolation between two adjoining enter ports. Furthermore, by means of meticulously arranging the positions of the eight antenna elements, proper polarization variety can additionally be correctly achieved, which similarly mitigates the coupling between antenna elements. A prototype used to be manufactured to validate the simulation. A excellent impedance matching (return loss &gt;10 dB), excessive isolation(&gt;17.5 dB), high complete effectivity (&gt;63%), and low envelope correlation coefficient (ECC, &lt;0.05) had been measured throughout the preferred operation bandwidth.

Antenna for IoT-Based Future Advanced (5G) Railway Communication With End-Fire Radiation

This work presents a design study of an antenna for future railway communications in the context of Internet of Things (IoT). 28-GHz resonance frequency has been considered for the 5G communication systems with end-fire radiations. The size of the proposed antenna array element is 100 mm <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times20$ </tex-math></inline-formula> mm. The shark-fin cover is used to cover the antenna to protect it from the external environmental effects. The proposed antenna along with the 1.3-GHz bandwidth centered at 28 GHz results an expected end-fire radiation ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\theta =83^{\circ }$ </tex-math></inline-formula> ), with a gain of >10 dBi and its suitability to be installed on the roof of the train for communications to the front and back directions along with the track has been studied and discussed in detail.

Rainbow-Link: Beam-Alignment-Free and Grant-Free mmW Multiple Access Using True-Time-Delay Array

The millimeter-wave (mmW) communications is a key enabling technology in 5G to provide ultra-high throughput. Current mmW technologies rely on analog phased arrays to realize beamforming gain and overcome high path loss. However, due to a limited number of simultaneous beams that can be created with analog/hybrid phased antenna arrays, the overheads of beam training and beam scheduling become a bottleneck for emerging networks that need to support a large number of users and low latency applications. This paper introduces rainbow-link, a novel multiple access protocol, that can achieve low latency and massive connectivity by exploiting wide bandwidth at mmW frequencies and novel analog true-time-delay array architecture with frequency dependent beamforming capability. In the proposed design, the network infrastructure is equipped with the true-time-delay array to simultaneously steer different frequency resource blocks towards distinct directions covering the entire cell sector. Users or devices, equipped with a narrowband receiver and either a single antenna or small phased antenna array, connect to the network based on their angular positions by selecting frequency resources within their rainbow beam allocation. Rainbow-link is combined with a contention-based grant-free access to eliminate the explicit beam training and user scheduling. The proposed design and analysis show that rainbow-link grant-free access is a potential candidate for latency-critical use cases within massive connectivity. Our results show that, given less than 1e-5 probability of packet loss, a rainbow-link cell, over 1 GHz bandwidth using 64 element antenna array, attains sub-millisecond user-plane latency and Mbps user rates with an approximate 400m line-of-sight coverage and a density of up to 5 active single antenna users per second per meter square.

Latest Performance Improvement Strategies and Techniques Used in 5G Antenna Designing Technology, a Comprehensive Study.

In the recent era, fifth-generation technology (5G) has not been fully implemented in the realm of wireless communication. To have excellent accessible bandwidth feasibility, and in order to achieve the aims of 5G standards, such as higher data rates and ultrahigh-definition video streaming, the millimeter wave (mmWave) band must be employed. Services with minimal latency and many other features are feasible only in the mmWave spectrum. To avoid numerous communication complexities such as high connection losses, short wavelength, and restricted bandwidth, as well as path-loss challenges in the mmWave range, an antenna with wide bandwidth, high gain, narrow steerable beam, high isolation, low side-lobe levels, and multiband features is required to alleviate these difficulties and meet 5G communication standards. To overcome these challenges, specific strategies and techniques should be employed in the traditional antenna designing procedure to excellently improve the performance of the antenna in terms of bandwidth, gain, and efficiency and to reduce the mutual coupling effect between the closely colocated antenna elements in MIMOs and arrays. The researchers reported on a variety of bandwidth and gain improvement approaches. To gain broader coverage, traditional antenna design techniques must be modified. In this study, the latest state-of-the-art work is reviewed, such as the role of the metamaterials (MMTs), parasitic patches, hybrid feeding, EBG structure, impact of the slots with different geometrical shapes in the radiator to achieve the goal of wide bandwidth, boosted gain, reduced side-lobes level, as well as stable radiation properties. Mutual coupling reduction techniques are also briefly reported. The role of reconfigurability is focused on in this study, and at the end, the future challenges in the field of antenna design and possible remedies to such issues are reviewed.

Performance Analysis of Optimal Analog Beamforming with Modified ESPRIT DOA Estimation Algorithm for MIMO NOMA System Over Rayleigh Fading Channel

In this paper, anefficient DOA estimation multi-input multi-output non-orthogonal Multiple Access (MIMO NOMA) system based on analog beamforming with modified ESPRIT (M-ESPRIT) algorithm is considered to minimize interference under the Rayleigh fading channel. Materials and Methods: An innovative Modified ESPRIT Direction of Arrival (M-ESPRIT DOA) estimation algorithm is used for user detection and to establish efficient communication. The proposed M-ESPRIT algorithm is compared with the existing MUSIC algorithm for a sample size of 20, taken for each group. Results: The performance of analog beamforming based MIMO NOMA system is measured in terms of capacity vs. Signal to Noise Ratio (SNR). The increased signal values due to the Singular Value Decomposition (SVD) method, while focusing on the desired user reduces the interference. From the simulation result, the mean capacity of the MIMO NOMA with MUSIC algorithm at 10dB SNR is 6 bps/Hz and at 20 dB SNR is 12 bps/Hz with 20 element antenna array and with 30 element array, capacity at 10 dB SNR is 11 bps/Hz while at 20 dB is 21 bps/Hz. With the M-ESPRIT algorithm, capacity at 10 dB SNR is 8 bps/Hz and at 20 dB SNR is 15 bps/Hz with 20 element antenna array and with 30 element array, capacity at 10 dB SNR is 12 bps/Hz and at 20 dB SNR is 24 bps/Hz.

Hyperparameter Optimization of Long Short-Term Memory-Based Forecasting DNN for Antenna Modeling Through Stochastic Methods

This letter presents an impressive optimization method for determining the optimal model hyperparameters of a deep neural network (DNN) targeted to model the characteristics of antennas. In this paper we propose an innovative approach of efficient yield analysis for modeling and sizing antennas. It is based on the long short-term memory (LSTM) DNN aiming to forecast the extended frequency responses, where various stochastic methods are applied for determining the optimal hyperparameters while training a DNN. Among the various methods, the one which models the antenna accurately in terms of input scattering parameter, gain, and radiation patterns is the winner. The proposed method is compact and addresses the problem of heavy reliance to the designer experience in determining the hyperparameters. Additionally, forecasting the future frequency responses of the antenna reduces the designers effort substantially in measuring large frequency band; hence, measuring whole frequency band would not be needed. For validating the effectiveness of the proposed method, the fabricated two element antenna array is used for modeling where the results demonstrate that the Thompson sampling (TS) algorithm can determine optimal hyperparameters with minimum error in comparison with other reported stochastic methods leads to predict the future frequency band accurately.

Thermoplastic Laminate and Cordierite/Indialite Glass-Ceramic Hybrid Package for 15-GHz Operated Antennas

This work describes a novel antenna package, a combination of a four-element array and a lens antenna performing the gain of 13.5 dBi, the bandwidth of 1 GHz and the total efficiency of 72% at 15 GHz. The <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2\times 2$ </tex-math></inline-formula> elements array antenna was designed and fabricated using square patches with a substrate through vias and a capacitive feeding on the novel dielectric substrate combination: thermoplastic laminate and cordierite/indialite glass-ceramic. The ceramic substrate was selected regarding its impressive dielectric properties such as the relative permittivity of 6.3 and a quality factor Qf 55 400 GHz. The array antenna performed with a reflection coefficient −20 dB over the bandwidth. The cascaded array with an extended hemispherical lens antenna enhanced the gain into the certain direction with narrow beamwidth properties. The packaged antenna is demonstrated for the 5G telecommunication systems especially where low losses, high-temperature resistance, and high-temperature stability are required.

An Effective Method for the Synthesis of Wideband and Wide-Scanning Sparse Planar Array

The matrix enhancement and matrix pencil (MEMP) has been used to reduce the number of array elements in the planar array with a shaped-beam pattern. This work extends the MEMP-based synthesis method to the synthesis of pattern reconfigurable sparse planar arrays in wide angle scanning and wide-band, which exploits a necessary restriction on finding the common element positions and individual element excitations for multiple patterns. Moreover, a unitary transformation is exploited into the multiple-composite equivalent Hankel matrix, which converts the complex computations of singular value decomposition (SVD) and eigenvalue decomposition (EVD) courses into real ones and effectively reduces the computation complexity. A new tactic is also restricted on avoiding too small element spacing with the consideration of the size of array antenna element. A set of numerical experiments is provided to validate the effectiveness and advantages of the proposed method.

Meta‐heuristic optimization algorithms for placement of multiple nulls and minimization of side lobe level in quadrant symmetric sparse array antenna

SummaryThe optimization of the non‐uniform planar array antenna parameter in order to minimize the signal interference in the electromagnetic environment through null placement is one of the most important areas of investigation in the field of wireless communication. This study deals with an effective method of synthesis of a quadrant symmetric sparse planar array antenna using the novel implementation of the well‐known meta‐heuristic optimization algorithms, namely, symbiotic organism search (SOS) and moth flame optimization (MFO) algorithms. The objective of this work is to place multiple small and wide nulls at the desired angles and simultaneously minimize the side lobe levels using a nonlinear mathematical approach. Three examples are presented with constraints that include the inter‐elemental distance, fixed number of array elements in the aperture, and the aperture size. The radiating antenna array elements are considered to have fixed uniform current distribution. The meta‐heuristic optimization approach offers the advantages of avoiding the infeasible solution while finding the best optimal set of element positions to reduce side lobe level in the desired radiation pattern. The radiation pattern characteristics and the computation time associated with each example and each algorithm are recorded and compared for arriving at the conclusion. The superiority of SOS is found in terms of the optimized side lobe levels. At the same time, both algorithms are found to be efficient in positioning the symmetric nulls in desired locations in the radiation pattern successfully. When compared with the published papers, proposed approach yields better results confirming the effectiveness of the performance of these algorithms.

Design of a novel compound decoupling structure for multiple‐input multiple‐output antenna array

A novel compound structure made up of Y-shaped microstrip interdigital lines, slots etched into the ground plane and metallized vias embedded in the substrate is designed to enhance the isolation between H-plane antenna array elements in this paper. Also, the operating mechanism of the decoupling structure is detailedly analyzed, as it can transform the coupling mode and suppress the transmission of surface current from one port to another. Then, after inserting the structure into the coupled antenna array, whose edge-to-edge distance between antenna elements is only 4 mm (0.07λ0), a 32.2 dB reduction of mutual coupling at the operating frequency 5.25 GHz is obtained. Moreover, the H-plane radiation pattern is modified, the radiation gain is increased, and the diversity performance is improved. Simulated results are in good accordance with measured results, verifying decoupling effectiveness of the proposed structure. The proposed structure has high feasibility in the utilization of MIMO or the wireless Rx/Tx system.

FPGA-BASED DATA COMMUNICATION SYSTEM IN DIGITAL SIGNAL PROCESSING DEVICES WITH PHASED ANTENNA ARRAYS

The paper represents some engineering solutions which provide coherence and coherent data transmission in radar and communication systems with phased array with computing components designed on the principles of FPGA-based reconfigurable computer systems. We developed the coherent gathering methods of digitized data from the phased array antenna elements, and data transmission among the distributed components that perform coherent digital signal processing. To provide coherent data processing and transmission, we use the signal of clock reference signal and the CPU-time, centrally generated and transmitted into all nodes with the same delay. Generation of all control signals in the processing nodes are based on these two signals. For data transmission, we suggest to use high-speed optical links, which are the most reliable in environmental conditions. To transmit the digitized data from phased array antenna elements, we suggested using packet data transmission with data integrity control and time-linked digitized data. Also, we applied a mechanism to monitor the delay mismatch of packets transmitted via different links and to synchronize them in data receivers. The most probable emergency situations for the data transmission system are considered and methods of parrying and minimizing the impact of transmission errors on the formation of the result are proposed. The developed engineering solutions were tested on a real FPGA-based beam-forming device with simulation of emergency situations. Many hours of tests and runs showed that all emergency situations were successfully solved by the data communication system.

Detection, Estimation and Radiation Formation Using Smart Antennas for the Spatial Location

The Electromagnetic (EM) waves are impinging on the base station from all the directions, Equally Spaced Uniform Linear Antenna Array (ESULA) are used to process these incoming EM waves to Detect and Estimate the directions of the mobile transmitters. After the process of Detection and Estimation, Electronic Beamforming is used to provide the narrow sharper beam towards the detected user. This Detection, Estimation and Beamforming plays a key role in variety of use cases like Radar, Wireless Communication and Sonar based systems. Smart Antenna Systems are implemented using two strategies namely Direction of Arrival (DoA) and Beamforming (BF). Direction of Arrival is a mechanism of Detecting and Estimating the directions of the mobile transmitters. Beamforming on the other hand is a process of transmission of the EM waves towards the source in a specific direction and providing the Spectral Nulls to other Interfering users. To increase the user capacity and to enhance the user experience Spatial Location based Spatial Division Multiple Access (SDMA) technology is used. To improve the overall performance of the smart antenna systems energy and packet delivery is majorly focused on specific source directions rather than using blind transmission strategy. In this paper performance analysis of algorithms for Direction of Arrival methods as well as the Beamforming methods have been performed. Experimental simulations are conducted and comparison is done with respect to Bias, Resolution and Time complexity for the Direction of Arrival methods. Noise Subspace Method (NSM) DoA algorithm consistently delivered the optimal bias, high resolution detection of the user location in spatial domain and provided lesser time complexity for both the scenarios which uses fewer antenna elements or larger number of antenna array elements at the base station. Similarly for the case of Beamforming methods the Mean Square Error and Beam-directions have been compared.

Multiuser steered signed quadrature spatial modulation for millimeter‐wave massive multiple‐input multiple‐output with hybrid beamforming

AbstractIn this article, signed quadrature spatial modulation (SQSM) scheme is intrinsically amalgamated with both fully digital geometric mean decomposition (GMD)‐based precoding technique and analog beamforming (ABF) for transmission over millimeter‐wave (mmWave) channel. Explicitly, the proposed scheme combines SQSM and GMD‐based hybrid beamforming (HBF) in downlink multiuser scenario, where the Frobenius norm‐based user selection algorithm is considered. This proposed scheme is denoted as multiuser steered SQSM (MUS‐SQSM). The ABF is used to mitigate the severity of the propagation loss in mmWave band by using power amplifiers and phase shifters. The performance of the proposed scheme in terms of both the bit error rate and the average mutual information is assessed in comparison to the conventional SQSM scheme performance. Simulation results show that significant improvements are realized by both the user selection algorithm and the application of ABF technique as the number of antenna array elements increases. It is also demonstrated that MUS‐SQSM scheme is robust against the channel estimation errors. Furthermore, the proposed MUS‐SQSM scheme with HBF benefits from the multiplexing gain of SQSM, the diversity gain of serving multiple users, and from the beamforming gain. All these gains increase the energy efficiency of the proposed model; thus, the proposed scheme can be considered in 5G wireless systems deployment.

Performance improvement of antenna array element for mobile communication

This work proposes a multiband structure for cell devices, as well as a microstrip patch antenna array for 5G and 4G implementations. For a square-shaped slot, the multiband array structure is expected to function at resonant frequencies of 20.5 GHz, 25.5 GHz, 32.5 GHz, and 40.5 GHz. The intended antenna was constructed on a FR4 substrate with a dielectric constant of 2.4 and a thickness of 1.6 mm. An antenna array composite consists of a 4*2 component of the multiband construction for tapered line feeding. The array antenna's dimensions are 28.24mm*16.48 mm. The suggested antenna's length and breadth are computed to enhance the antenna array element's size. The antenna presented is appropriate for both 4G and 5G applications. In this article, several characteristics such as reflection coefficient, gain, and radiation pattern are examined.