Wideband Antenna Array Research Articles

Decoupled Hepta-Band Antenna Array for WWAN/LTE Smartphone Applications

A wideband antenna array incorporating a neutralization line (NL) for port decoupling for smartphone applications is proposed. The U-shape NL is employed to achieve enhanced isolations for the lower band, which are better than 10 dB for 824-960 MHz. The mechanism of the NL is explained based on the S-parameters and the surface current distributions. In addition, the incorporated NL has acceptable effects on the bandwidth, while a bandstop filter and on-ground slots are utilized to realize the hepta-band coverage, covering the GSM850/900/1800/1900/UMTS/LTE2300/2500 operation. A prototype is fabricated and tested, with S-parameters, radiation efficiencies, radiation patterns, envelope correlation coefficient (ECC), and mean effective gain (MEG) presented.

Status of the ITER Ion Cyclotron H&CD system

The ongoing design of the ITER Ion Cyclotron Heating and Current Drive system (20MW, 40–55MHz) is rendered challenging by the wide spectrum of requirements and interface constraints to which it is subject, several of which are conflicting and/or still in a high state of flux. These requirements include operation over a broad range of plasma scenarios and magnetic fields (which prompts usage of wide-band phased antenna arrays), high radio-frequency (RF) power density at the first wall (and associated operation close to voltage and current limits), resilience to ELM-induced load variations, intense thermal and mechanical loads, long pulse operation, high system availability, efficient nuclear shielding, high density of antenna services, remote-handling ability, tight installation tolerances, and nuclear safety function as tritium confinement barrier. R&D activities are ongoing or in preparation to validate critical antenna components (plasma-facing Faraday screen, RF sliding contacts, RF vacuum windows), as well as to qualify the RF power sources and the transmission and matching components. Intensive numerical modeling and experimental studies on antenna mock-ups have been conducted to validate and optimize the RF design. The paper highlights progress and outstanding issues for the various system components.

PROSPECTS FOR THE DEVELOPMENT OF PHASED ANTENNA ARRAYS

This article describes the main achievements in the development of phased antenna arrays (par) in the past decade. Provides an overview of the most famous systems based on the PAR and PAR based on MMIC technology - PAR in radar stations, PAR to control the laser and optical beams. The existing options for the design of the PAR:ferroelectric antenna array; plasma antenna with electronic scanning; reflective grating on 100-mm semiconductor wafers; wideband antenna arrays with aperture; antenna arrays with digital beam forming.

A MINIMIZED WIDEBAND ANTENNA ARRAY WITH DECOUPLING NETWORKS FOR UHF RFID APPLICATIONS

A minimized wideband antenna array is presented for ultra-high frequency (UHF) radio frequency identiflcation (RFID) reader applications. The antenna array consists of two E-shaped patch antennas and a feeding network, with the overall size 200 £ 100 £ 20mm 3 . The feeding network could efiectively decrease the antenna mutual coupling and improve the bandwidth. The measured bandwidth is about 68MHz (896{964MHz) under the condition of voltage standing wave ratio (VSWR) less than 2, which covers various RFID bands including North American (902{928MHz), Chinese (920{ 925MHz) and Japanese (952{955MHz). The average gain is 4.5dBi in UHF band. The principles of the antenna and the feeding network are also discussed and analyzed in this paper. At last, the key parameters are studied and show the antenna robustness.

THE DESIGN OF AN OPTICAL TIME STEERED ANTENNA BASED ON A NEW INTEGRATED TRUE TIME DELAY UNIT

In the framework of wide-band and ultra wide-band array antennas, an Optical Time Steered Antenna (OTSA) is presented, by considering the design strategies of a new True Time Delay (TTD) Control Unit in the Beam Forming Network (BFN). The unit has high reliability, low crosstalk, low switching time and potential low cost, being based on a low cost technology. Furthermore, due to its compactness and modularity, it can be easily grouped with other ones to make a control unit of large arrays. Difierent strategies and working conflgurations of the TTD control unit are presented as a trade-ofi among hardware complexity, insertion loss reduction and beam control capability. The design of an OTSA prototype is discussed by considering a realistic model simulating the behavior of a real world antenna and accounting for unavoidable non-realities, such as random, periodic and systematic errors introduced by each device exploited in the OTSA as well as mutual coupling between radiating elements. An optimal trimming strategy, able to compensate at best for BFN errors and based on the use of suitably located trimmers, is presented. Among other cases, to enlighten the potentialities of the OTSA, an all optical architecture providing a difierence beam squint free pattern is also proposed.

메타재질구조의 UWB 전력 분배기를 이용한 광대역 배열 안테나를 위한 급전부 설계

In this paper, a new method is suggested to reduce the size of a wide-band array antenna. The power-divider for the feeding structure is made compact as with the help of a novel Metamaterial UWB bandpass filter. This power divider is clearly different from others in that the proposed design uses microstrip structured Composite Right and Left-Handed (CRLH) filters, while others use two dielectric layers or long tapered transmission lines. In order to validate the proposed design method, the circuit and full-wave simulated results of the power divider with the Metamaterial UWB filters are compared to each other, and the Metamaterial properties of the structure are shown with the electric field at the ZOR and dispersion diagram. Furthermore, the antenna performance of the fabricated antenna with the power divider is measured and compared with the prediction. Also, the size reduction effect by the proposed scheme is addressed.

ULTRAFAST AUTONOMOUS DETECTION AND SCANNING SYSTEM BASED ON OPTOELECTRONIC PULSE SWITCHING

A novel method allowing the ultrafast scanning of an area thanks to an Ultra Wide Band (UWB) antenna array is proposed in this paper. This method is based on the use of asynchronous optical pulses trains with difierent repetition rates obtained in amplifled regenerative cavities. By means of optoelectronic switching, providing short powerful electrical pulses trains to an UWB antenna array, it is possible to spatially scan a large area in less than 1ms. The paper presents the principle of the transient beam steering and its potentialities to realize an ultrafast detection system.

A Wideband High-Gain Dual-Polarized Slot Array Patch Antenna for WiMAX Applications in 5.8 GHz

A low-cost, easy-to-fabricate, wideband and high-gain dual-polarized array antenna employing an innovative microstrip slot patch antenna element is designed and fabricated. The design parameters of the antenna are optimized using commercial softwares (Microwave Office and Zeland IE3D) to get the suitable <svg style="vertical-align:-0.1254pt;width:11.375px;" id="M1" height="10.725" version="1.1" viewBox="0 0 11.375 10.725" width="11.375" xmlns="http://www.w3.org/2000/svg"> <g transform="matrix(1.25,0,0,-1.25,0,10.725)"> <g transform="translate(72,-63.42)"> <text transform="matrix(1,0,0,-1,-71.95,63.6)"> <tspan style="font-size: 12.50px; " x="0" y="0">𝑆</tspan> </text> </g> </g> </svg>-parameters and radiation patterns. Finally, the simulation results are compared to the experimental ones and a good agreement is demonstrated. The antenna has an approximately bandwidth of 14&#x25; (5.15&#x2013;5.9&#x2009;GHz) which covers Worldwide Interoperability Microwave Access (WiMAX)/5.8. It also has the peak gain of 26&#x2009;dBi for both polarizations and high isolation between two ports over a wide bandwidth.

Comparison of different antenna arrays for the BER reduction in indoor wireless communication

In this paper, we use the ultra wideband antenna array combined with particle swarm optimization PSO to minimize the BER for indoor communication systems. Three types of antenna arrays, namely the circular shape, L shape, and Y shape arrays, are used in the transmitter and their corresponding BER on several paths in the indoor environment are calculated. On the basis of the topography of the antenna array and the BER formula, the array pattern synthesis problem can be reformulated into an optimization problem and solved by the PSO. The novelties of our approach is not only choosing BER as the object function instead of the sidelobe level of the antenna pattern, but also considering the antenna feed length effect of each array element. The particle swarm optimization algorithm is employed to optimize the excitation voltages and feed lengths for these antenna arrays to reduce the BER. The strong point of the PSO is that it can find the solution even if the performance index cannot be formulated by simple equations. By the obtained antenna patterns, we can know the route with the lowest BER; meanwhile, transmission power using this route can be reduced. Numerical results show that the synthesized antenna array pattern is effective in focusing maximum gain to the line-of-sight path for these antenna arrays. The synthesized array pattern also can mitigate severe multipath fading in complex propagation environments. As a result, the BER can be reduced substantially in indoor ultra wideband communication systems. The investigated results can help communication engineers improve their planning and design of indoor wireless communication.Copyright © 2011 John Wiley & Sons, Ltd.

Wideband antenna array beam steering with free-space optical true-time delay engine

A 6–12 GHz Vivaldi wideband antenna array made of four sub-arrays (two elements per sub-array) was built to steer the beam with a White cell optical true-time delay (OTTD) engine. The OTTD engine was simulated to produce delays with a time delay increment of 25 ps. The beam is then steered combining the simulated OTTD delays and the measured mutual coupling of a Vivaldi array to a maximum scan angle of ±50°. The results demonstrate that the effect of optical losses and mutual coupling effects of the combined beam steering system is not negligible and must be carefully accounted for when implementing frequency-independent TTD beam steering systems.

Finite impulse response-filter-based RF-beamforming network for wideband and ultra-wideband antenna arrays

In this study, a wideband electronic beamforming concept applicable for ultra-wideband short pulse systems is derived and experimentally demonstrated. In particular, a finite impulse response (FIR)-filter-based beamforming network is configured such that an antenna array yields a desired radiation pattern within a predefined frequency range. An experimental verification of a wideband transmission system is presented for the frequency range from 1.5 to 2.0 GHz. The transmit system consists of a wideband power divider feeding a matrix of analogue FIR-filters. These FIR-filters control a circular antenna array of four elements. The receiver consists of a single antenna element. Measurements are performed in frequency domain using a vector network analyser. The results show an almost frequency independent radiation pattern with a half power beamwidth of 72 and a maximum sidelobe level of 10 dB.

Ultra wideband antenna array on the basis of 8×8 shaped slot radiators

Numerical analysis results of electromagnetic connection between radiating elements in scanning ultra wideband (2…12 GHz) antenna array that consists of 9×9 Vivaldi antennas are presented. Using these results and the suggested efficient synthesis methodology a sample ultra wideband antennas array that consists of 8×8 identical shaped slot radiators was developed, manufactured and experimentally studied. Measurements results of VSWR and radiation pattern of the sample array demonstrated that it array provides scanning within ±30° in E-plane with VSWR < 2 and retention of radiation pattern in the frequency range 5…10 GHz for the spacing between neighbor radiators equal to 15mm(λ/2 at 10 GHz).

Optimal Wideband Beamforming for Uniform Linear Arrays Based on Frequency-Domain MISO System Identification

Frequency-invariant (FI) beamforming for wideband antenna arrays inevitably involves array aperture loss at the higher-end frequencies of the bandwidth. In order to minimize aperture loss and to fully utilize the array aperture at different operation frequencies, an optimal wideband beamformer for uniform linear array (ULA) is designed based on Dolph-Chebyshev's theory of beamforming. Different from the existing FI beamformers for wideband arrays, our wideband beamformer produces frequency-dependent patterns which have the narrowest mainlobe width for any given equiripple sidelobe level over a wide frequency bandwidth. These frequency-dependent patterns are obtained through using the system identification method to determine the transfer function of the beamforming network. A matrix formulation is developed to calculate the frequency-dependent optimal Riblet-Chebyshev weights for element spacings smaller than half wavelength. The transfer function of the beamforming network, which is treated as an equivalent multi-input and single-output (MISO) system, is then obtained by the method of system identification with the optimal frequency-dependent Riblet-Chebyshev weights as the input data. Numerical results are provided to verify the effectiveness and validity of the proposed method.

Nature-Inspired Design Techniques for Ultra-Wideband Aperiodic Antenna Arrays

Over the past few decades, much research has been invested in the exploration of wideband and ultra-wideband (UWB) antenna arrays. The goals of such array designs are to determine the best element arrangements, which yield radiation patterns possessing the highest degrees of side lobe suppression, and no grating lobes over the largest possible operating bandwidths. It has been recently shown that nature-inspired array-design methodologies can provide solutions that exhibit these ultra-wideband characteristics. This article provides an overview of two such designs: linear polyfractal arrays, and planar arrays of aperiodic tilings. Robust nature-inspired genetic-algorithm optimization techniques were utilized in the design of both types of arrays in order to obtain the best-possible UWB performance. This article also discusses the fabrication and experimental validation of two 32-element linear polyfractal array-design prototypes, which exhibited close agreement to the radiation performance predicted by simulation. These experimentally validated arrays possessed wide bandwidths with suppressed grating lobes and relatively low sidelobes for their size (-16.3 dB at f <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> and -5.39 dB at f <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> )Additional simulations discussed in this paper showed that the benefits of these methodologies are amplified when applied to larger sized array designs (Le., arrays with larger element counts). One example exhibited a peak sidelobe level less than -19.34 dB over a 40:1 bandwidth.

Wideband dual‐polarized stacked‐patch antenna array for base stations

AbstractIn this article, a 16‐element antenna array for wireless communication services is presented. The antenna operates in the universal mobile telecommunications system (UMTS), ISM, 2.4 GHz worldwide interoperability for microwave access, and in the new UMTS 3G expansion band from 2500 to 2690 MHz. A prototype of the antenna has been realized and measured. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 1048–1052, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25131

A Novel Wideband and Compact Microstrip Grid Array Antenna

A wideband and compact microstrip grid array antenna is presented. The antenna is printed on a dielectric substrate, backed by a metal board, and directly fed from a 50 ¿ coaxial cable. It adopts elliptical radiation elements to enhance its impedance and gain bandwidths, and sinusoid lines to reduce its size. Structural parameters of a proposed antenna with 7 radiation elements were optimized by a parallel genetic algorithm (GA) on a cluster system. A prototype antenna was fabricated and tested. Results of simulation and measurement agree well and show the antenna exhibits encouraging properties, e.g., S <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sub> < -10 dB bandwidth of 25% and a 3 dB gain-drop bandwidth of 16.3%, both of which are much wider than that of conventional grid array antennas, as well as a maximum gain of approximately 13.7 dBi with an area-reduction factor of 47%.

On the accuracy of localization systems using wideband antenna arrays

Accurate positional information is essential for many applications in wireless networks. Time-of-arrival (TOA) and angle-of-arrival (AOA) are the two most commonly used signal metrics for localizing nodes with unknown positions. In this paper, we consider a wireless network in which each node is equipped with a wideband antenna array capable of performing both TOA and AOA measurements. Since both the position and orientation of the agent are of interest, we propose a localization framework that jointly estimates these two parameters. The notion of equivalent fisher information is applied to derive the squared error bounds for the position and orientation. Since our analysis starts from the received waveforms rather than directly from the signal metrics, these bounds characterize the fundamental limits of the position and orientation accuracy. Surprisingly, our result reveals that AOA measurements obtained by wideband antenna arrays do not further improve position accuracy beyond that provided by TOA measurements.

Frequency Selective Surfaces for Extended Bandwidth Backing Reflector Functions

This paper deals with the use of frequency selective surfaces (FSS) to increase the efficiency X bandwidth product in wideband antenna arrays, whose efficiency is limited by the front-to-back ratio. If the backing reflector for the antenna is realized through a single metal plane solution, its location will be suitable only on a relatively limited frequency range especially if wide angle scanning is required. In order to extend the frequency range of usability, an FSS can be sandwiched between the antenna and the ground plane, providing an additional reflecting plane for an higher frequency band. The possibility to integrate in the antenna different functionalities, otherwise performed by several antennas, is also discussed in the paper. The proposed backing structure composed by the FSS and the ground plane has been designed to be used in conjunction with a wideband antenna consisting of an array of connected dipoles. A hardware demonstrator of the backing structure has also been manufactured and tested.

Integrated Wideband 2-D and 3-D Transitions for Millimeter-Wave RF Front-Ends

This letter reports on broadband 3-D and 2-D transitions on flexible organic liquid crystal polymer (LCP) substrate with return loss below 15 dB for frequencies up to 110 GHz. The presented novel 3-D coplanar waveguide-coplanar waveguide-microstrip (CPW-CPW-MSTRIP) transition features an insertion loss (IL) of 0.45 dB for a 3.3-mm total (longitudinal) length of transition, while the novel 3-D CPW-CPW transition has an IL of 0.25 dB for a 2.8-mm (longitudinal) length of transition. These transitions require strategically placed vias and tapering of the CPW ground planes in order to suppress radiation loss and optimize the performance over a very broad frequency range. This letter also includes a 90° CPW bend that shows a return loss lower than 15 dB up to 100 GHz and an insertion loss of 0.75 dB for a 6.35-mm total length of the transition. All these transitions are simple to realize and are compatible with low-cost substrate fabrication guidelines allowing for the easy integration of ICs in 3-D modules, especially in compact automotive radar applications and beam-steering wideband antenna arrays. An example of the integration of the proposed 3-D transitions with a practical antenna array is presented, and experiments verify the very good performance of the integrated topology up to 100 GHz.

Analysis and design of wideband widescan planar tapered slot antenna array

Phased arrays have been required to operate over wide bandwidths and wide scan angle to support multifunction operation in both telecommunication and radar. In response to that need, this study firstly analyses the performance of the connected planar tapered slot antenna array and finds that the mutual coupling is essential and has good effect in wideband antenna array design. Then the authors design a wideband widescan planar tapered slot antenna array system with novel dual-parabola tapered slot antenna elements and feed network. This array can operate from 1.6 to 9 GHz and scan angle up to 45°. Both simulation and measurement results are shown to certificate the performance of the proposed antenna array.