Antenna Array Elements Research Articles

Using the Long Wavelength Array to Search for Cosmic Dawn

The search for the spectral signature of hydrogen from the formation of the first stars, known as Cosmic Dawn or First Light, is an ongoing effort around the world. The signature should present itself as a decrease in the temperature of the 21[Formula: see text]cm transition relative to that of the Cosmic Microwave Background and is believed to reside somewhere below 100[Formula: see text]MHz. A potential detection was published by the Experiment to Detect the Global EoR Signal (EDGES) collaboration with a profile centered around 78[Formula: see text]MHz of both unexpected depth and width (Bowman et al. [2018] Nature 555, 67). If validated, this detection will have profound impacts on the current paradigm of structure formation within [Formula: see text]CDM cosmology. We present an attempt to detect the spectral signature reported by the EDGES collaboration with the Long Wavelength Array station located on the Sevilleta National Wildlife Refuge in New Mexico, USA (LWA-SV). LWA-SV differs from other instruments in that it is a 256 element antenna array and offers beamforming capabilisties that should help with calibration and detection. We report first limits from LWA-SV and look toward future plans to improve these limits.

Development of 60-GHz millimeter wave, electromagnetic bandgap ground planes for multiple-input multiple-output antenna applications

For 60-GHz band communications, both the mutual coupling and transmission distance restrict the performance of a multiple-input multiple-output (MIMO) antenna array. Several studies presented different types of meta-materials and electromagnetic bandgap (EBG) structures to improve the performance of a MIMO antenna array at the 60-GHz band. In this paper, we presented the four-element MIMO patch antenna with different types of EBG structures for the millimeter wave (mmW)communications at the 60-GHz unlicensed industrial, scientific, and medical band. The single element of the MIMO antenna array covered the mmW band from 57 GHz to 63 GHz having the dimensions of 1.3 mm × 1.8 mm × 0.1 mm. We developed a set of square-shaped, cross-shaped, and complex-slotted EBG ground planes between the antenna elements for the performance improvement. All the three EBG ground planes provided significant coupling reduction between the mmW MIMO antenna elements. The proposed EBG structures exhibited wide bandgap characteristics and improved scattering parameters in the desired frequency band. In contrast with the cross- and complex-slotted, the square-shaped EBG structure substantially improved the overall gain of MIMO antenna array. In addition, the square-shaped EBG reformed the maximum beam and enhanced the far-field gain pattern in the desired direction. Experimental results conducted with the fabricated prototypes showed a good agreement with the simulation results and adequately covered the 60-GHz band. The low-profile and salient features of the proposed MIMO antenna array shows the potential for on-chip applications at 60 GHz.

Multi-Beamforming Provided by Dual-Wavelength True Time Delay PIC and Multicore Fiber

This paper presents a multi-beamformer based on a dual-wavelength photonic integrated circuit (PIC) and multicore fiber (MCF) capable of providing independent delay tuning to two separate beams modulated on different optical carriers. This implementation enables a centralized control of the photonic beamformer, connecting each element of a phase array antenna with a dedicated core of a MCF link and controlling the induced delay (resulting steering angle) by thermo-optically adjusting the heaters of the PIC. The dual-wavelength PIC implements true time delay (TTD) based on optical ring resonators (ORRs). Six different ORR heaters’ configurations are evaluated experimentally, obtaining an induced delay of up to 328 ps at 19 GHz RF. With a measured delay resolution of 4 ps, it is recommended to increase/decrease the delay in small steps (between 10 and 30 ps) in order to keep the switching time in the ms range. Higher delays increments can be induced within longer switching time, e.g. 328 ps requires 1.68 s to stabilize the heaters. The performance demonstration includes the dual-wavelength transmission over 1-km of 7-core MCF and evaluates single-carrier data signals in the K-band centered in 19 GHz RF with up to 4 GHz bandwidth (BW). Operation with OFDM standard WiFi and WiMAX signals is also demonstrated experimentally. A delay of 328 ps can be induced to data signals at 19 GHz RF with up to 3-GHz BW, while 4-GHz BW signals can operate with up to 166 ps delay increment. An almost constant EVM is obtained for each BW below 3 GHz, confirming that changing the beam-steering angle does not affect the quality of the signal.

In brief

PAGE 476 Chinese researchers present an irregular pentagonal patch array antenna, featuring a multilayer structure to enable dual-band and multi-mode orbital angular momentum (OAM) generation. The proposed array has the potential generate 6 different OAMs in 3 frequency bands and may provide new ideas for generating multi-mode vortex electromagnetic waves. PAGE 482 A multiplier design technique for stochastic computing is presented. The proposed design offers exact output and latency in the order of 2N, where N = the input precision. Compared to state of the art deterministic methods, the proposed design is faster by a factor of 2N. The technique is verified by mathematical analysis and simulation. Schematic diagram of proposed antenna array's element PAGE 501 Researchers from the Republic of Korea demonstrate integrated one-dimensional optical phase arrays (OPAs) for wide-angle, two-dimensional beam-steering in a 26.5 mm2 area. The 2-D OPA consists of 16 1-D transversal steering OPAs, whose radiators have different grating periods – allowing assignment of different longitudinal angles. Carry save adder in proposed design for N = 3. Full adder and half adder are denoted by fa and ha respectively. PAGE 510 Chinese researchers present an edge-attention-based geodesic distance which can be applied to the simple linear iterative clustering (SLIC) framework for PolSAR image superpixel segmentation, improving performance without an increase in computational expense. Experiments show the superiority of the proposed distance both qualitatively and quantitatively. Structure and design parameters of the grating radiator. PAGE 490 A collaboration of Chinese researchers propose two schemes to help prevent unwanted sideslip by wheeled mobile robots when turning. A controller is proposed combining robust control and model predictive control. Together the longitudinal velocity can be adjusted according to the state of the robot, whilst the model predictive control is used to achieve path tracking. Superpixel segmentation on PolSAR images over Changle using SLIC with the proposed distance. Fuzzy-NMPC system structure.

Dual-Polarized Ka-Band Vivaldi Antenna Array

This article presents a high-performance fully metallic dual-polarized wideband Vivaldi array for the $Ka$ -band (26–40 GHz), which is going to be used, for example, in 5G millimeter-wave (mmWave) communication networks. Antenna-array elements are fed straight from a single printed circuit board (PCB) that allows integrating active components in the immediate proximity of antenna elements. A whole array can be placed on a PCB as a through-hole or surface-mount technology component. The antenna is simulated in a unit cell with periodic boundary conditions and in an $8\times8$ array configuration. The simulations show that the active reflection coefficient is below −10 dB across the entire $Ka$ -band and throughout most of the beam-steering angles up to ±60°. Lower than 3 dB scan loss is achieved in approximately ±60° range in the elementary planes and ±50° in the diagonal planes. The reflection coefficient and gain of each of the four elements in different parts of the manufactured dual-polarized $8\,\,\times8$ array were measured and simulated with the remaining elements terminated with a $50~\Omega $ load. The measured results follow closely the full-wave finite array simulation results; the reflection coefficient is low and the element pattern is wide over the entire frequency range.

Secure Wireless Communications Based On Antenna Array Elements

Configuration of antenna array system to offer directional dependent modulation has the capability of enhancing the security level of data transmission against eavesdroppers’ attacks. In this paper, Frequency diverse array (FDA) antenna for physical–layer security in wireless communications has been proposed. The proposed method provide a range and angle dependent directional modulation scheme using FDA with frequency increments to improve physical-layer security point-to-point communications. It maintains the objective of changing the progressive phase shifts at each symbol transmission. Thus the emitted pattern at each symbol transmission period will be range and angle dependent. Consequently, the proposed method offers a robust physical-layer security for wireless transmission, as the transmitted signal will be deliberately distorted along the undesired positions, but can be successfully decoded by the intended receiver position. Numerical results are presented to validate the effectiveness of the proposed method.
 
 
 
 Keywords: Frequency diverse array; Physical-layer security; Directional antenna modulation; Wireless communication; Range and angle dependent.
 
 

Design and Implementation of a Corporate Fed Two Element Antennae Array using Miters

In wireless communication systems, designing of antennae with required parameters is an challenging issue. So, The approach in this paper is to design a corporate fed 2 element antenna array is designed to operate at 2.4 GHz using an FR-4 substrate of height h=1.6mm. For wireless application all the antenna parameters are analysed for two element array antenna with element spacing λ, λ/2 and with miters. It is observed that bandwidth decreases by decreasing the element spacing. But by using miters for antenna with element spacing bandwidth and reflection coefficient are improved. All the antennae are fabricated and tested using VNA E5071C.

Joint 3D Trajectory Design and Time Allocation for UAV-Enabled Wireless Power Transfer Networks

This paper considers a rotary-wing unmanned aerial vehicle (UAV)-enabled wireless power transfer system, where a UAV is dispatched as an energy transmitter (ET), transferring radio frequency (RF) signals to a set of energy receivers (ERs) periodically. We aim to maximize the energy harvested at all ERs by jointly optimizing the UAV's three-dimensional (3D) placement, beam pattern and charging time. However, the considered optimization problem taking into account the drone flight altitude and the wireless coverage performance is formulated as a non-convex problem. To tackle this problem, we propose a low-complexity iterative algorithm to decompose the original problem into four sub-problems in order to optimize the variables sequentially. In particular, we first use the sequential unconstrained convex minimization based algorithm to find the globally optimal UAV two-dimensional (2D) position. Subsequently, we can directly obtain the optimal UAV altitude as the objective function of problem is monotonic decreasing with respect to UAV altitude. Then, we propose the multiobjective evolutionary algorithm based on decomposition (MOEA/D) based algorithm to control the phase of antenna array elements, in order to achieve high steering performance of multi-beams. Finally, with the above solved variables, the original problem is reformulated as a single-variable optimization problem where charging time is the optimization variable, and can be solved using the standard convex optimization techniques. Furthermore, we use the branch and bound method to design the UAV trajectory which can be constructed as traveling salesman problem (TSP) to minimize flight distance. Numerical results validate the theoretical findings and demonstrate that significant performance gain in terms of sum received power of ERs can be achieved by the proposed algorithm in UAV-enabled wireless power transfer networks.

A wide‐band rhombus monopole antenna array for millimeter wave applications

AbstractThis article presents a simple antenna array for millimeter‐wave communications at 28 GHz. The proposed antenna array is 40 × 19.22 mm2 in size and operates in a measured 26.04 to 30.63 GHz frequency range. The antenna array elements are excited by a planar four‐way feed network, which has been designed and optimized for optimum performance. The single element of the proposed antenna array is a rhombic monopole surrounded by a series of vias, square parasitic patches were etched on the back side to enhance its impedance performance. The proposed antenna array has a peak gain of 11.24 dBi with radiation efficiency more than 85% in its entire operating band. Both single and its 4 × 1 array have been modeled, simulated, and fabricated using standard PCB process. Excellent agreement exists between the simulated and measured results. The antenna's simple design, compact size, and low fabrication cost, enables it to be deployed in millimeter‐wave communication systems.

Mitigation of Multipath Effects Based on a Robust Fractional Order Bidirectional Least Mean Square (FOBLMS) Beamforming Algorithm for GPS Receivers

Consideration on positioning and location services among the public has been increasing in the recent years with their applications in most of the anticipating milieus such as automobile navigation system etc. This insists for a development of high recitation global navigation satellite system such as global positioning system (GPS). Multipath effects, interference, signal jamming etc. are the major sources of error influencing the performance of the GPS receiver. Literature presents many of the multipath mitigation techniques. Among them, adaptive processing technology based beamforming algorithms appears a viable solution for multipath mitigation. The least mean square (LMS) beamforming algorithms were sensitive to dynamic environments thus affecting the accuracy of GPS. In this paper, an adaptive beamforming algorithm called fractional order bidirectional least mean square (FOBLMS) algorithm is proposed to mitigate the multipath effects and to conceal the jammer signal in a GPS receiver. The FOBLMS is an integration of the fractional calculus and bidirectional least mean square algorithm. The effectiveness of the proposed algorithm is validated using the bit error rate and experimentation gain results over the existing beamforming algorithms. Experimental results demonstrated that the performance of the proposed beamforming algorithm is better than LMS algorithm with maximal relative antenna gain of 28.92 dB, 32.84 dB for two and four element antenna arrays at − 60° and 10°, direction of arrivals respectively. The outcome of this work would be useful for developing a robust technique for multipath mitigation in GPS receivers.

Antenna Array Pattern Synthesis Using an Iterative Method

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.

Improving the Performances of Microstrip Antenna Array using Defected Ground Structure

In this paper, a two elements antenna array with defective ground structure (DGS) has been designed to achieve significant gain, polarization purity and reduced mutual coupling. A 3 port Wilkinson power divider has been designed at 4.5 GHz frequency to obtain equal power distribution at the output ports. Two Rectangular microstrip patch antennas with DGS at the corners yield improved gain, impedance matching and polarization purity in both E and H plane. The reduction of mutual coupling and side lobe level (SLL) have been achieved by placing the dumbbell shaped DGS bellow the feed line of the power divider. The radiation performances obtained using the fabricated prototype agrees well with that of the simulated one. This array has been designed for C-band application.

Design of Crescent Shaped 64-Elements Flexible Patch Antenna Array for the Application of Uterine Tumour Detection

In this paper, a crescent shape 64 (8 × 8) elements microstrip patch array, using rubber substrate is designed and simulated to function at 4 GHz for the application of uterine tumour detection. A comparison using various combinations of antenna array elements is also presented. The centre-to-centre patch element distance is kept 0.5λ (λ = guided wavelength) for the antenna array to control mutual coupling. Electromagnetic simulator Ansoft HFSS 13 is used for the simulation. Characteristic analysis e.g. return loss(RL), radiation pattern of patch antenna array have been investigated. This antenna is placed on human uterine phantom model and simulated to detect uterine tumour. 64-elements antenna array has been fabricated also. In this paper, RL of -26.8384 dB & antenna gain of 21.0271 have been achieved for the proposed array. Human uterine phantom model is designed and simulated by CST Studio Suite 2019.

Design and development of planar antenna array for mimo application

Multi-Input Multi-Output (MIMO) is the need for recent communication system for the enhancement of channel capacity. While the number of antenna array elements increased, the spacing between the array elements and size of the antenna reduced. Hence high coupling between the elements occur, and thus the channel capacity reduced. There were several existing methods employs, however there were some limitations like reduced gain, dielectric constant, and bandwidth. So as to overcome this and to increase the performance characteristics such as bandwidth, gain of MIMO antennas and to lessen the dielectric constant of substrate material this proposed scheme is introduced. Using these considerations and requirements, an array of two-element MIMO system will be designed and developed with a less dielectric material ( $$ \varvec{\varepsilon}_{{\varvec{r }}} < 4 $$ ). So in this Taconic RF-35 (dielectric constant is 3.5), Two T-Shaped antennas are employed for 2.45 GHz (ISM band) with multiple modes of operation to achieve the improved bandwidth of about − 10 db. Simulation is done by HFSS 13.0.

Decoupling and Matching Strategies for Compact Antenna Arrays

This paper proposes and evaluates three strategies of joint decoupling and impedance matching networks (DMN) for antenna arrays. Since MIMO technology presents antenna arrays which can be formatted with elements of the order of tens to hundreds, several effects due to this structure have emerged, such as mutual coupling and impedance matching among antenna elements in array. Therefore, the treatment of these issues seeks to solve problems such as the degradation of the performance of the communications system. The first method called DMN with Lumped Elements (DMN-LE) performs the decoupling and impedance matching steps with capacitors and inductors. The second method is called DMN with Ring Hybrid (DMN-RH). It utilizes a microstrip line in the ring form. With this approach is due achieves first the decoupling followed by impedance matching step. The third method is called Networkless Decoupling and Matching (NDM). It brings a concept of decoupling without the presence of a network itself. This enables modeling an antenna array that performs DMN operations in a simplified and compact manner. A comparison of the methods is performed bothanalytically and via computer simulations. We conclude that the third method is promising new alternative approach.

ПОВЕДЕНИЕ ИНФОРМАЦИОННОГО ПАРАМЕТРА ГЛИССАДНОГО РАДИОМАЯКА СИСТЕМЫ ПОСАДКИ ВОЗДУШНЫХ СУДОВ В ШИРОКОМ СЕКТОРЕ УГЛОВ МЕСТА

The article is devoted to the problem of information protection generated by a glide path beacon of the PRMG format for providing instrumental approach of aircraft for landing. To en-sure a safe approach, the radio beacon landing system forms a descent trajectory in space - a glide path. A developed multilevel control system is designed to ensure the integrity of the land-ing system by continuous monitoring of the position of a given glide path and the steepness of the indicated glide path parameter. However, during flight tests of a glide path beacon (GPB), a false glide path is sometimes detected in the area of the landing system, which naturally vio-lates its integrity. The article shows the reason for this phenomenon - a violation of the multi-plicity of the heights of the suspension of the radiating elements of the GPB antenna array. Flight measurements data of the glide path zone at the airfield in the foothills are given. The experimental results confirm the theoretically found regularities in the behavior of the informa-tion parameter of the glide path beacon in a wide sector of angles. Recommendations are pro-posed for maintaining the integrity of the landing system

A Grounded Coplanar Waveguide-Based Slotted Inverted Delta-Shaped Wideband Antenna for Microwave Head Imaging

A wideband grounded coplanar waveguide (GCPW) based patch antenna for head imaging is discussed in this paper. The proposed antenna is integrated with a slotted inverted delta-shaped main radiating patch, coplanar waveguide elements, and slotted partial ground. The prime objective of usages of coplanar waveguide elements is enhancing antenna effectiveness. In the prototype, examined different categories of slots in the ground and particularly rectangular and elliptical-shaped slots are used to improve the radiation directivity, gain, and efficiency. The optimized dimension of the antenna is $50\times 44\times 1.524$ mm3 by using the Rogers RO4350B substrate. The measured and simulated results demonstrate that the proposed prototype has a bandwidth of 2.01 GHz (1.70–3.71 GHz) with nearly directional radiation characteristics. The highest gain of the prototype is 5.65 dBi, and the maximum 93% radiation efficiency over the frequency band. The antenna has a lower group delay, higher fidelity factor (>95%), which are significant factors for microwave head imaging. Various design structures are performed to achieve the most satisfactory result. The proposed prototype is designed and analyzed by 3D CST 2019 simulator software. Later, the antenna is fabricated and measured to examine the performance. Thereafter, a single antenna and twelve-antennas array element are configured and placed surrounding the 3D realistic shaped Hugo head model to validate the effectiveness of the single antenna as well as the designed antennas array. The antenna has satisfactory field penetration into the human head tissues with a safe SAR (specific absorption rate). Less than 0.00233 W/kg SAR is attained over the operating frequency range, which is lower than the reported antennas. The Iteratively Corrected Delay Multiply and Sum (IC-DMAS) imaging algorithm will be applied for imaging purposes. The investigation through the literature of the statistical and measured data evident that the proposed antenna is apposite for the wideband microwave head imaging applications.

Разработка и экспериментальное исследование АФАР КВ-диапазона с управляемой диаграммой направленности

There is a promising direction in the antenna field design of a stationary transmitting radio center short-wavelength range is the use of active phased array antennas with spatial power addition and a controlled directional pattern. The article considers the algorithm for calculating the V shaped antenna as a basic element of antenna array, apart from that it considers calculation of the four-element antenna array based on the V shaped antenna. This paper presents the track tests results to estimate the power increment depending on the operating elements in the antenna array, as well as horizontal controllability results.

ОПТИМАЛЬНА ОБРОБКА СИГНАЛІВ ЗОБРАЖЕНЬ НА ФОНІ ШУМОВИХ ПЕРЕШКОД В ІНФОРМАЦІЙНІЙ СИСТЕМІ З АДАПТИВНОЮ АНТЕННОЮ РЕШІТКОЮ

The method to restore image signals against the arbitrary intensity noise background in the information radio engineering system with adaptive antenna array has been developed. In order to use methods developed for processing one-dimensional signals for image recovery in the information system with adaptive antenna array, the transition from the two-dimensional array to vector representation is carried out. Mathematical model of narrowband signal formed at input of antenna array elements in space-time sense is obtained. Correlation matrices of image carrier signals, interference and noise are considered and features of adaptive processing of image signals coming from several sources are observed. An expression was found for the likelihood function if the incoming vector process is a multivariate stationary Gaussian process with a non-zero mean. According to the maximum likelihood criterion, the expression for the system of optimal independent parametric weight vectors necessary for image signals restoring against the arbitrary intensity noise background coming from several independent sources in the information system with adaptive antenna array is obtained. In accordance to this system, a signal processing algorithm is built in the adaptive processor of N-dimensional adaptive antenna array. A simulation model of image signal restores coming from one source in the information system with adaptive antenna array against the arbitrary intensity noise background coming from several independent sources is built. It is shown that the use of weight coefficients calculated on the basis of the correlation matrix of observations, due to its properties, does not allow dividing the set of correlated image signals. The direction of further development of the obtained results in the class of invariant methods is determined.

Binary Operating Antenna Array Elements by using Hausdorff and Euclidean Metric Distance

In this paper, the linear antenna array is designed by the usage of Woodward–Lawson method. The design procedure fits antenna array radiation pattern to a predefined/required radiation mask. In this study will be investigated the possibility of powering off some antenna elements without modifying the behavior and power ratio of the elements which remains on. The aim of powering off antenna elements is to reduce power consumption of the designed array antenna and to reduce power dissipation problems on modern full digital beam forming architecture. The choice of binary operation of antenna element (on/off) reduces computational effort required for complex beam forming techniques. The results can be stored on look-up tables, in order to be recalled on demand by antenna operator. There are used two different metrics to identify how close, to the required design, is the modified antenna pattern. Euclidean and Hausdorff distances are both used as score of the modified array performance. The obtained solutions shows the applicability of binary operations on existing antenna array and the metric can be effectively used as ranking solutions.