Showing papers on "Reflective array antenna published in 2016"

8-antenna and 16-antenna arrays using the quad-antenna linear array as a building block for the 3.5-GHz LTE MIMO operation in the smartphone

Abstract: Using the quad-antenna linear (QAL) array as a building block, the 8-antenna and 16-antenna arrays for the 3.5-GHz long term evolution multiple-input multiple-output (MIMO) operation in the smartphone are demonstrated. The QAL array has a planar structure of narrow width 3 mm (0.035λ) and short length 50 mm (0.58λ), with λ being the wavelength at 3.5 GHz. For the 8-antenna array, two QAL arrays are disposed along two opposite side edges (denoted as Array A) or the same side edge (denoted as Array B) of the system circuit board of the smartphone. The obtained envelope correlation coefficient values of the antennas in Array A and B are shown. The calculated channel capacities for Array A and B applied in an 8 × 8 MIMO system are also analyzed. The 16-antenna array formed by four QAL arrays disposed along two opposite side edges (denoted as Array C) is then studied. For operating in a 16 × 16 MIMO system, the calculated channel capacity of Array C can reach about 66–70 bps/Hz with a 20-dB signal-to-noise ratio. The obtained channel capacity is about 5.7–6.1 times that (11.5 bps/Hz) of the upper limit of an ideal 2 × 2 MIMO system with 100% antenna efficiency for the antennas therein. Details of the proposed Array A, B, and C are described, and the obtained results are presented. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:174–181, 2016

Performance Analysis of Millimeter-Wave Phased Array Antennas in Cellular Handsets

Abstract: This letter discusses the usage of high-gain steerable antenna arrays operating at millimeter-wave (mmWave) frequencies for future cellular networks (5G). Based on the probable outline of the 5G networks, a method for characterizing phased array antennas in cellular handsets has been introduced. For analyzing the performance, the total scan pattern of the array configuration together with its respective coverage efficiency are essential to consider in order to compare different antenna designs and topology approaches with each other. Two design approaches and subarray schemes of these have been considered in order to illustrate the relevance of such a characterization method. The results show the importance of evaluating potential array antennas in such manners. The method can be applied to much more complex system models, where polarization diversity, hand and body effect, and statistical modeling of the channel may be included.

Dual-Band and Dual-Circularly Polarized Shared-Aperture Array Antennas With Single-Layer Substrate

Abstract: This paper presents a new approach to implement planar shared-aperture dual-band dual-circular polarization (CP) array antennas. The antennas can be fabricated on a single-layer substrate and extended to a larger array easily. In this approach, each array element is obtained by connecting two patches working at different frequencies directly. To form arrays with higher gain, two kinds of feed networks are described, which can be applied in systems where narrowband and wideband are needed, respectively. One is using the conventional feed network and the other is using the sequential rotation technique to further improve the CP axial ratio (AR) performance. Two prototype arrays with $4 \times 4$ elements are fabricated and tested in $X/Ku$ bands. Experimental results show that good CP characteristics are obtained, which agree well with the simulation results. For the first narrow-band prototype array, the 3-dB AR bandwidth is around 1.5% for both bands. For the second array using the sequential rotation technique, the bandwidth of return loss and AR are wider. In the lower band centered at 12.1 GHz, the ${-}10\hbox{-}\text{dB}$ return loss bandwidth is 8.3% and the 3-dB AR bandwidth is 14.2% [right-hand CP (RHCP)]; in the higher band centered at 17.4 GHz, the corresponding data are 18.9% and 14.9% [left-hand CP (LHCP)], respectively.

Pattern Reconfigurable Antenna Array With Circular Polarization

Abstract: A design for arrays with beam-steering capability in the azimuthal plane is described. The array is a four-sector antenna configuration, and each sector element can generate unidirectional radiation with circular polarization (CP). A reconfigurable $1\times4$ power divider with broadband operation is designed and used to excite the sector elements. By controlling PIN diodes, the divider can offer 11 states for the four outputs, and each state is corresponding to one CP radiation pattern of the array. Prototypes for the sector array and the tunable divider are, respectively, constructed, and the experimental results of the integrated structure demonstrate that, in addition to the beam-steering capability, the array can also generate bidirectional and omnidirectional radiation patterns between 1.9 and 2.3 GHz. Moreover, these steerable beams and radiation patterns have a cross polarization of less than $-18$ dB for all azimuthal angles.

Design of UWB Antenna for Air-Coupled Impulse Ground-Penetrating Radar

Abstract: This letter presents a new transverse electromagnetic flared horn antenna for the demanding requirement of an air-coupled impulse ground-penetrating radar. Structure anatomy is performed focusing on achieving good impedance matching throughout the wide frequency band. The design procedure starts with constructing an analytic model to evaluate the preliminary physical dimensions to achieve minimum reflections. Structural fine tunings are then performed for optimization. The antennas are fabricated and tested. Experimental results validate the design effectiveness.

Microstrip Phased-Array In-Band RCS Reduction With a Random Element Rotation Technique

Abstract: The techniques of random antenna element distribution and rotation have been proposed to design a low sidelobe and low cross-polarization phased array or reflect array for a long time. In this communication, we demonstrate that the use of randomly rotated (RR) elements can provide random scattering phases and phase center distributions, which can lead to an in-band radar cross section (RCS) reduction for the array. To illustrate the effectiveness of the proposed method, three $8 \times 8$ circularly polarized (CP) microstrip arrays, 1) the uniform array without rotation; 2) sequentially rotated (SR) array; and 3) RR array, are compared and analyzed. Results indicate that the RCS of the RR array can be reduced significantly, even in the main beam region, while maintaining its high radiation performance.

Low-Profile Wideband Monopolar UHF Antennas for Integration Onto Vehicles and Helmets

Abstract: A novel design of a low-profile wideband monopolar antenna is proposed with integration examples for vehicles and helmets. Initially, a monopolar antenna size is reduced by adding four symmetrical tapered slots on an edge-shorted patch. The antenna is first designed to be integrated onto a large flat ground plane that is applicable for vehicular installation. This design is later adapted for integration onto a helmet with a finite-curved ground plane, where the helmet material is included as part of the design. This study shows that a curved ground plane improves the radiation patterns at broadside and further reduces the antenna height. Both vehicle and helmet antennas have been optimized to operate in a wide frequency range from about 800–2300 MHz. These antennas radiate in a monopole-like pattern with vertical polarization and high radiation efficiency that makes them suitable for transmission applications. Good agreement between simulation and measurement is obtained, which ultimately validates the proposed design technique.

Scalable Multibeam Antenna Arrays Fed by Dual-Band Modified Butler Matrices

Abstract: A concept of dual-band multibeam antenna arrays that allows for efficient utilization of a common aperture has been proposed. The presented antenna arrays allow for achieving $N$ -independent beams pointing at $N$ different directions at higher frequency and $N$ -independent beams at lower frequency pointing at $N/2$ different directions and having two orthogonal polarizations. As feeding networks, novel modified Butler matrices (BMs) have been proposed in which directional couplers having different properties in two frequency ranges have been for the first time utilized. To confirm the theoretical analysis, a dual-band multibeam antenna array fed by a modified $4\times4$ BM has been developed operating in 2.4 and 5.2 GHz frequency ranges.

Robustness of Wearable UHF-Band PIFAs to Human-Body Proximity

Abstract: The robustness of wearable UHF-band planar inverted-F antennas (PIFAs), with respect to body–antenna separation and human tissue dispersion, is addressed through numerical investigations. The main goal is gaining physical insights into the relationship between the grounded antenna performance and the distribution of the electric and magnetic energy densities in the antenna near-field region close to the ground plane border. A criterion for choosing a proper shape of the antenna ground plane is suggested, which can improve the antenna robustness with respect to the random variations of the body–antenna coupling scenario, but with a minimal impact on the antenna size.

Graphene-Based Dipole Antenna for a UHF RFID Tag

Abstract: This paper describes the design and measurements of a remote frequency identification (RFID) tag built of a graphene-based dipole antenna and a chip operating in the ultrahigh-frequency (UHF) band in accordance with the EPC Global Class 1 Gen 2 standard A custom-designed antenna has been designed first Then, it was used to construct several tags that have been tested with a standard RFID reader to reveal that each one is fully operational, although the interrogation range for the graphene-based circuits has been limited in comparison to copper antennas This can be attributed to increased sheet resistance of a graphene layer and—in the case of tags fabricated on paper—also to significant dielectric losses of the substrate material However, it seems that for applications where the interrogation range is not crucial the novel antenna can be an alternative to much more expensive circuits printed with silver-based inks

Coupling effects in MIMO phased array

Abstract: In Coherent MIMO phased array, different codes are transmitted at the same time by the different antenna elements (or subarray). Compared to classical transmission (linear phase law on the array antenna to focus the beam in one direction), MIMO transmission is very stressful for the array because of random like phase between adjacent elements and even in some cases opposite phase between adjacent elements. In this context, the paper present a general frame to describe coupling effect in MIMO Phased array, involving a circuit modeling of the antenna array and exploiting mutual impedances between antenna elements. Illustrations are provided with exact simulation of a dipole array.

A Compact Directional Slot Antenna and Its Application in MIMO Array

Abstract: In this communication, a new design for the microstrip-fed slot antenna with a directive radiation pattern for WLAN/WiMAX application is presented. By utilizing a two-element array topology, a unidirectional radiation pattern is obtained. Without any directors and reflectors, the proposed slot antenna shows advantages in terms of compact size and high front-to-back gain ratio in the azimuthal plane. Four directional slot antennas are then placed in a square loop array to obtain nearly orthogonal patterns. Thus, a compact multiple input multiple output array with high isolation among those four elements is achieved. Simulated and measured results are presented to validate the practicality of the proposed antenna structures.

Nonuniform Broadband Circularly Polarized Antenna Array for Vehicular Communications

Abstract: Road safety applications drive the development of vehicular communications as support to intelligent transport systems. The communications network necessary for this is supported by dedicated short-range communications (DSRC), which is based on roadside units (RSUs) and onboard units. In the RSU, the DSRC physical-layer standards, along with practical issues, require specific radiation patterns of the respective antenna, leading to the use of unusual arrays of antennas. This paper describes a new concept based on a binomial array structure, which simplifies the design of the antenna array while ensuring good performance. The new structure developed for this antenna enabled the design of a feed network using unbalanced power dividers in the same plane as that of the radiating elements, maintaining the favorable characteristics of microstrip antennas. The array thus obtained met the desired specification, in terms of a radiation pattern with a bandwidth greater than 1 GHz.

Localization of Passive UHF RFID Tags Using the AoAct Transmitter Beamforming Technique

Abstract: The localization of passive ultra-high frequ- ency (UHF) radio frequency identification (RFID) tags is an emerging technology that has reached a high level of interest in industry and research. Most solutions use classical techniques, such as the angle-of-arrival or the received-signal-strength methods. As an alternative, we present a new approach for estimating the position of a passive UHF RFID tag by using a transmitter beamforming technique that we call angle-of-activation (AoAct). It is based on manipulating the shape of the radiation pattern of the interrogator’s transmitter antenna array. By pivoting the main lobe of the pattern in the azimuth plane of the array and by utilizing the very sensitive response threshold of passive UHF RFID tags, we are able to estimate the tag direction. We use three-channel digital beamforming, where the phases and amplitudes of the antenna array’s feeding radio frequency signals are controlled by the baseband $I$ and $Q$ components of the interrogator’s transmitter signal. Our self-developed hardware pivots the main lobe of a three-element antenna array in a range of ±52° with a resolution of 0.02°. It senses the AoAct with a mean measured accuracy of 1.2° in the anechoic chamber, 1.9° in a basic multipath environment, and 2.5° in a real-world multipath environment. After estimating the AoAct of a tag from different locations, the tag position is triangulated. Experiments show that our AoAct system delivers a localization accuracy of 7 cm in a typical multipath environment.

Highly Directional Steerable Antennas: High-Gain Antennas Supporting User Mobility or Beam Switching for Reconfigurable Backhauling

Abstract: Modern millimeter-wave (mmWave) communication systems for large indoor areas and most outdoor scenarios require high-gain antennas with beam-steering ability to support user mobility or beam switching for reconfigurable backhauling. In this article, two new concepts for the development of highly directional steerable mmWave antennas are proposed and analyzed. The first one is modular antenna array (MAA) technology, which allows the creation of large-aperture, high-gain adaptive antenna arrays in a cost-effective and scalable manner. Two MAA configurations based on the existing phased subarray module are considered and analyzed for mmWave small-cell access and backhauling. The second prospective technology that fulfills the required antenna parameters for mmWave smallcell flexible backhauling is the lens-array antenna (LAA). The combination of the dielectric lens for aperture increasing with only one subarray module with beam-steering capabilities may provide 25?30-dBi total antenna gain with azimuth sector sweeping !45?.

On-Chip Antenna Integration for Millimeter-Wave Single-Chip FMCW Radar, Providing High Efficiency and Isolation

Abstract: A complete functional 60-GHz BiCMOS single-chip millimeter-wave frequency-modulated continuous wave (FMCW) radar with on-chip integrated antennas is designed, realized, and experimentally validated. The chip is configured with one transmitting and two receiving antennas. A high antenna efficiency and isolation between the transmitting and receiving antennas is achieved by using a cavity-backed on-chip monopole and by optimizing the package environment. Surface-wave losses and back radiation are reduced, and a high antenna gain is obtained with small ripples in the antenna pattern by implementing special structures on the PCB of the integrated circuit package. The experimental results from the single-chip radar show that the on-chip antennas provide a gain of 2 dBi with very low back radiation. The realized antennas achieve an impedance bandwidth of more than 50% with a corresponding simulated efficiency of 45%. In addition, the proposed approach suppresses surface waves and meets the specific FMCW radar requirements, such as a more than 25-dB isolation between the transmitting and receiving antennas.

Two-dimensional full-hemisphere frequency scanning array based on metamaterial leaky wave antennas and feed networks

Abstract: This paper presents a novel two-dimensional (2-D) frequency scanning antenna array that can exhibit a full-hemisphere coverage of radiation beams. The proposed 2-D frequency scanning antenna array utilizes transmission-line based microwave metamaterials (MTMs) to realize both leaky wave antennas and antenna array feed networks. By engineering the dispersion of both metamaterial leaky wave antennas and metamaterial feed networks, the proposed passive 2-D MTM antenna array is able to perform one-to-one frequency-space mapping and beamforming over the entire full-hemisphere without using any phase shifters or mixers.

Aperiodic Antenna Array for Secondary Lobe Suppression

Abstract: We propose an aperiodic antenna array to suppress secondary radiation lobes in widely spaced arrays. We show that the use of Fermatn’s spiral as a template for the antenna array leads to similar results in terms of sidelobe level and bandwidth as those obtained by computationally expensive non-linear optimization methods. Furthermore, by maintaining the distances between neighbors approximately constant, the increase in array footprint is kept approximately within 25% of an equivalent periodic array, a key feature for space-constrained applications. Based on the straightforward computation of our method, we are able to present the results for arrays varying from 4 to 2048 elements and minimal spacing between the antennas up to ten wavelengths.

Design of bowtie-slot on-chip antenna backed with E-shaped FSS at 94 GHz

Abstract: To meet the growing demand for miniaturization and compactness, antennas are being designed over CMOS chips. On-chip antennas (OCAs) suffer from low gains and radiation efficiency due to high dielectric constant and low resistivity of Silicon. Artificial magnetic conductors (AMC) are used in OCAs to increase gain and reduce power confinement in the substrate. In this paper, a bowtie slot antenna is presented whose gain is enhanced by an array of back-to-back E-shaped (B2BE) frequency selective surface (FSS). The operating frequency of antenna is 94 GHz where its gain is boosted from −2.71 dBi to −1.94 dBi. Designed in a standard IHP 130nm BiCMOS process without any extra post-processing step, the S11 is below −10dB from 90 GHz to 105 GHz with an antenna size of 710×310×650 µm3

Energy efficient switched parasitic array antenna for 5G networks and IoT

Abstract: This paper includes design and implementation result of an adaptive beam forming antenna for upcoming 5G and Internet of Things (IoT). Switched parasitic array antennas are low cost, small sized and compact circular array antennas that steer beam in a desired direction by variation in switching pattern of parasitic elements. The proposed antenna design has an active center element, which is surrounded by several symmetrically placed parasitic elements. The designed antenna has a gain of 8 dB and is capable of 360 degrees beam steering in steps of 60 degrees each. Simulations are validated with results of the fabricated antenna. Antenna beam is steered by controlling parasitic elements. Future application of Electronically Steerable Parasitic Array Radiator (ESPAR) antennas and switched parasitic array antennas in next generation communication networks and methods for reducing size of the antenna are also highlighted.

Mutual Coupling Mitigation in Broadband Multiple-Antenna Communication Systems Using Feedforward Technique

Abstract: An efficient method to mitigate the forward scattering (shadowing) effect and the near-field coupling among elements of broadband multiple-antenna communication systems is proposed. The technique is based on provision of a passive feedforward coupling among elements to cancel out the mutual couplings. Electrical current paths, with appropriate shape, location, and length, between adjacent elements are established to provide current distributions on adjacent elements that are approximately equal in magnitude and out of phase with the induced current on the same antenna due to the near-field coupling and scattering effects. As the coupling level decreases, the radiation pattern of an excited array element, in the presence of the other array elements, approaches the pattern of the antenna element in isolation. The technique is first detailed for a two-element wideband monoconical antenna array and is then extended to a uniform 12-element circular array of the same monoconical antennas where only feedforward paths are applied to circumferentially adjacent elements to reduce the coupling over a very wide bandwidth. The experimental results indicate that the application of the proposed feedforward technique to a 12-element circular array of monoconical antennas can provide a minimum of 2-dB reduction in the average gain deviation from omnidirectional radiation over an about 30% fractional bandwidth. Another important feature of the feedforward technique is removal of radiation nulls of the array elements at all frequencies and all directions.

A 94GHz 4TX-4RX phased-array for FMCW radar with integrated LO and flip-chip antenna package

Abstract: A prototype phased-array IC with four transmitters, four receivers, and integrated LO generation was designed and fabricated in a 130nm SiGe BiCMOS technology. Including LO phase shifter power consumption, the transmit array consumes 71mW per element with a per-element output power of +6.4dBm at 94GHz. The receiver array consumes 56mW per element, and achieves an RX element noise figure of 12.5dB at 94GHz. Integrated LO generation includes a 47GHz VCO, 2× frequency multiplier, 94GHz LO buffers, and a 32× CML divider chain. The transceiver has been integrated into a flip chip antenna module with four transmit and four receive antennas, and achieves TX and RX beam steering over a scan angle range of ±20°. Including LO and bias overhead power, the array has improved per-element power consumption compared with state-of-the-art 94GHz arrays, consuming only 106mW per TX channel and 91mW per RX channel, while achieving comparable performance and levels of integration.

A Low-Cost Wideband Circularly Polarized Slot Array With Integrated Feeding Network and Reduced Height

Abstract: This letter proposes a wideband unidirectional circularly polarized (CP) slot array with a truly planar structure, which integrates the feeding network on a single substrate. The height of the array is reduced by half compared to traditional arrays with a reflector. Four parasitic slots are etched at the edges of the ground plane to improve the gain performance when the height is reduced. The measured results show that the bandwidths (BWs) for impedance, axial ratio (AR), and gain are all more than 23%, and these three bandwidths almost cover the same frequency band. The proposed array has a good unidirectional pattern and can be used in base-station applications.

Distributed on-chip antennas to increase system bandwidth at 180 GHz

Abstract: This paper presents integrated, distributed on-chip antennas. The aim is to achieve a higher system bandwidth due to the utilization of multiple antennas and the combining of their frequency ranges. All designs will be manufactured in the 130nm IHP SG13G2 process. Furthermore the measurement setup is described and measurement results are shown.

Grating Lobe Suppression With Discrete Dipole Element Antenna Arrays

Abstract: Antenna arrays with interelement spacing as integral multiple of wavelength λ have been absent in practical implementations despite their highly directive main lobe; the disuse is primarily attributed to the presence of grating lobes. This letter proposes a modification in a linear antenna array whereby the grating lobes are suppressed by up to 100% with an additional improvement in the directivity of main-lobe and reduction in other sidelobe levels. A new array factor is synthesized by replacing the individual elements in a linear array with a pair of elements called discrete dipole elements (DDEs); a background theory of spatial hard windowing is proposed for the synthesis of array factor. Array factors of linear array made of eight DDEs are compared to those of an eight-element linear isotropic array to validate the claims. The proposed DDE array is then fabricated using monopole antennas; a good agreement between measured, simulated, and analytical results is seen.

VHF/UHF antenna pattern measurement with unmanned aerial vehicles

Abstract: The characterization of VHF and UHF antennas is very challenging owing to the very low-operative frequency. This paper presents a novel technique (originally developed for radio-astronomical applications) that can be suitable to measure ground-based aerospace antennas in real installation conditions, with an accurate and cost-effective method which does not require additional infrastructures. The system mainly consists of a micro Unmanned Aerial Vehicle (UAV), equipped with both a RF transmitter and an antenna, properly designed to operate as a far-field artificial test-source. Experimental results on a ground-based antenna at 50 MHz are provided. The extension of this technique to characterize service antennas (telemetry, remote control) onboard aerial vehicles is also reported. A measured pattern example of a 433 MHz telemetry monopole mounted on a commercial UAV is shown.

Improved genetic algorithm for the configuration optimization of the sub arrays in phased array radar

Abstract: As the dramatic development of the electronic technology, many of the traditional radar system has been threaten in the modern war. Therefore, we need new technology to overcome all these kinds of problems. The phase array radar is a good solution to all these problems. The phase array radar is constructed of many antenna elements and each antenna element has its own phase shifter. However, the phase array always have a huge amount of money spent on the hardware. This is because each antenna has its own receive path. In order to reduce the hardware cost, we propose a novel algorithm to divide the phase array into the sub arrays. In addition, in order to make the operation be easier, the antenna elements of the sub array should be relatively centered. The simulation results shows our proposed algorithm works well.

Low-profile scalable phased array antenna at Ku-band for mobile satellite communications

Abstract: This paper discusses the design of an 8×8 phased array antenna tile for Ku-band mobile satellite communications. The array has low-profile, high-gain, and wide-angle scanning properties. The design steps and electromagnetic analysis of a dual-polarized radiating antenna element and an 8×8 array tile comprised of these radiating elements are presented. The array structure makes it possible for satellite communication (SATCOM) terminals with compact sizes, because the whole front-end might be on the same multilayer printed circuit board (PCB). With a compact geometry and 25% bandwidth, the array promises an excellent performance for satellite communication applications. The radiation characteristics and other array parameters are evaluated with respect to the application requirements.

A switched-beam linearly-polarized transmitarray antenna for V-band backhaul applications

Abstract: This paper presents the design of linearly-polarized switched-beam transmitarray antennas operating in V-band for wireless backhaul applications in future mobile communication networks. These arrays are based on a simple printed-circuit-board structure with only three metal layers and no via connection in order to minimize the insertion loss, the fabrication complexity and the overall cost of the system. In a fixed-beam configuration, the antenna exhibits a broadside gain of 32 dBi at 60 GHz with a 3-dB bandwidth of 20% and a very low cross-polarization level. Beam switching can be implemented using an array of five switched patch antennas as a focal source. A beam-switching capability of ±6.1° in one plane with a maximum gain of 29.3 dB and less than 3 dB of gain ripple are demonstrated.