Azimuth Plane Research Articles

A Flexible Dual-Band Rectenna With Full Azimuth Coverage

This paper presents a novel cylindrical shaped dual-band flexible rectenna capable of harvesting RF energy from number of RF sources available in the entire azimuth plane. The proposed configuration is an array of four identical dual-band rectenna subsystems, printed on the lightweight flexible substrate. Here, each rectenna subsystem comprises of a dual-ring shaped dual-band monopole antenna and a dual-band rectifying circuit. The designed topology is good for popular bands of LTE 1.8 GHz and Wi-Fi 2.45 GHz. The robustness of the designed antenna in the proposed cylindrical shaped rectenna is also verified by testing it for different bending angles in the H-plane by simulation as well as measurement. The bending performance is tested for the antenna using S11 and farfield radiation pattern. Further, for extracting maximum RF signals in the entire azimuth plane, these four identical antennas are backed by a wide-band artificial magnetic conductor (AMC) placed in the inner region of the cylinder. The fabricated single rectenna unit is capable of converting power with 40% efficiency at very low input RF power −12 dBm. Finally, the overall rectenna array is fabricated and validated through measurements using two different test antennas as a RF sources in the real environment of lab. The proposed light weight, rectenna printed on a flexible substrate can extract RF signals from a number of randomly distributed RF sources simultaneously, while maintaining the overall compact configuration.

A Novel Multidirectional Strain Sensor Realized by a 3D Microstrip-Line Fed Near-Circular Patch Antenna

In this paper, we propose a newly developed impedance method to gauge the variations of multidirectional strain using a near-circular-patch based sensor. A novel three-dimensional (3D) feeding mechanism realized by a 90-deg bended microstrip line is devised for allowing strain detection along any direction in the azimuth plane of a metallic surface. The simulated results, verified by experimental results, demonstrate that there is a linear relationship between normalized impedance and multi-directional strain with high sensitivities of about 100 ppm/μe. The relationship between sensitivity and sensor orientation is derived as a cosine function, which is a useful feature for estimating principal strain direction.

ВАРІАНТ СТРУКТУРИ СИСТЕМИ АВТОМАТИЧНОЇ СТАБІЛІЗАЦІЇ ПЛАТФОРМИ АНТЕННОГО ПОЛЯ РУХОМОГО ОБ’ЄКТУ

The article proposes a variant of constructing a digital system for automatic stabilization of the antenna field platform located on an object (vehicle), and also considers the structural diagrams of control channels. The choice of executive devices to ensure the performance and accuracy of the system is substantiated. The conditions of use, restrictions and initial data necessary for the synthesis of the automatic stabilization system are determined, the principles of calculating by the system - the coordinates of the position of the antenna field platform in space - are highlighted.The prerequisites for the use of a platform with stabilization at the facility is the need to ensure the most efficient use of communication facilities (antenna systems) in a complex electromagnetic environment and to reduce the deployment (folding) time, adjust radio and satellite communications in the operational-tactical and tactical control levels.The system of automatic stabilization of the antenna field platform will provide optimal conditions for the interaction of antenna systems that are part of the antenna field of radio-electronic means of the compact constellation. Optimal conditions should be understood as vertical placement of omnidirectional antennas, the possibility of changing the position of directional antennas in the azimuthal plane and ensuring the electromagnetic compatibility of radio electronic means. The deviation of the platform from the required angular positions of the reference coordinate system can be determined by accelerometers or other devices that measure the linear acceleration of an object in a given plane.It is proposed to stabilize the platform through two channels for each of the axes. The angular position of the stabilized platform in space is specified in the reference coordinate system, which is not associated with a moving object (vehicle) that is moving, and in a moving coordinate system, it is rigidly connected with this object. It is proposed to use an inertial coordinate system as a reference coordinate system, that is, motionless relative to the horizon, which is oriented at a given point on the earth's surface. The proposed automatic system is universal, with the ability to adapt to the driving performance of a moving object. Adaptability is ensured by the presence in the control loop of an automatic stabilization system of circuits, the parameters of the transfer functions of which are pre-calculated for the tactical and technical characteristics of the moving object.

Fast normalized cross-correlation for measuring distance to objects using optic flow, applied for helicopter obstacle detection

The fast normalized cross-correlation (NCC) calculation method presented here features low computational requirements, which makes it suitable for being implemented in real time onboard micro-controllers with very few computational resources. This method was adapted for making distance measurements, using a high speed optic flow sensor operating at 20m∕s. An application of this study is to develop a proof of concept of an innovative optic flow sensor fixed at the tip of an helicopter’s blade (from Airbus Helicopter) to measure the distance to various obstacles (wall, cliff...) in the azimuthal plane (rotor plane) during hovering flight. Due to its small size, this sensor developed in this paper can also be also adapted for Micro aerial vehicles (MAVs). This method of calculation requires less memory than the reference method, at the expense of some extra arithmetical operations, but it is still significantly lighter than the classical NCC method. An algorithm for implementing this method in real-time robotic applications is presented. Experimental results confirm the efficiency of this highly time-saving method.

Pattern‐reconfigurable antenna in azimuth plane using SP3T reconfigurable switching network

This paper presents a new pattern-reconfigurable antenna. This antenna has been designed, fabricated, and measured for 2.45 GHz band application. It provides six different radiation patterns in the azimuth plane at the same angle interval. First, a new single-pole three-throw switching network with one input and three outputs has been built on the circuit simulator and afterward validated by structural simulation. This reconfigurable switching network provides six switching conditions by the combination of turning ‘ON’ and ‘OFF’ states of the used four radio frequency p-i-n diode switches. Second, three curved printed dipole antennas are designed with an equal interval of 120° in the azimuth plane. Finally, switching network and curved printed dipole antennas are simultaneously simulated for 2.45 GHz band applications followed by fabrication. Maximum half-power beamwidth and average gain are obtained as 110° and 4 dBi, respectively, and the radiation efficiency is always better than 90.2%.

Slot-Based Pattern Reconfigurable ESPAR Antenna for IoT Applications

In this article, a slot-based electronically steerable parasitic array radiator (ESPAR) antenna suitable for Internet-of-Things (IoT) applications is proposed. The antenna can provide 12 directive and two slightly different omnidirectional radiation states. The 12 directive patterns allow the antenna to focus the radiated energy toward six different directions uniformly distributed in the azimuth plane and with two different beamwidths. The reconfiguration of the radiation pattern is based on the use of low-capacitance low-power consuming diodes that can be digitally controlled. This article details the design of the antenna structure and the practical implementation of the reconfiguration mechanism, discussing the effects of real electronic components on the antenna performance. The antenna effectiveness is numerically and experimentally assessed.

E- and H-Plane Constant Beamwidth Horn Antenna Over 4:1 Frequency Band

A wideband corrugation slot, called stepped-shape slot, is proposed in the design of E-plane corrugated double-ridged horn antenna (DRHA) with H-plane pin sidewalls to extend the constant beamwidth bandwidth (BW) of horn antennas. Closed-form expressions for the input admittance of the new slot are derived, and the BW is compared with the BWs of other conventional corrugations. The proposed slot presents wideband characteristics with a BW ratio of more than 4:1. The use of stepped-shape slot in a corrugated wall keeps the surface reactance capacitive over a relatively large frequency band. The H-plane sidewalls of the designed antenna are formed by curved pinwalls. The flare includes ridges to extend the frequency range, and the E-plane walls are corrugated with a wideband slot to improve the beamwidth constancy in elevation. Thus, constant beamwidth horn antenna (CBWHA) is obtained at both azimuth and elevation planes over the desired frequency band from 4.5 to 18 GHz. The measured performance of the proposed CBWHA reveals wideband characteristics with 31.0° ± 2.5° H-plane and 37.4° ± 5.2° E-plane half power beamwidths over 4:1 frequency range.

Identifying the nature of the QCD transition in heavy-ion collisions with deep learning

In this proceeding, we review our recent work using deep convolutional neural network (CNN) to identify the nature of the QCD transition in a hybrid modeling of heavy-ion collisions. Within this hybrid model, a viscous hydrodynamic model is coupled with a hadronic cascade “after-burner”. As a binary classification setup, we employ two different types of equations of state (EoS) of the hot medium in the hydrodynamic evolution. The resulting final-state pion spectra in the transverse momentum and azimuthal angle plane are fed to the neural network as the input data in order to distinguish different EoS. To probe the effects of the fluctuations in the event-by-event spectra, we explore different scenarios for the input data and make a comparison in a systematic way. We observe a clear hierarchy in the predictive power when the network is fed with the event-by-event, cascade-coarse-grained and event-fine-averaged spectra. The carefully-trained neural network can extract high-level features from pion spectra to identify the nature of the QCD transition in a realistic simulation scenario.

A Wideband Tightly Coupled Slot Antenna for 360° Full Azimuthal Beam Steering Applications

A single-layer planar coupled-slot antenna is presented for 360° azimuthal beam scanning applications over a wide frequency band. Eight sets of antennas each consisting of three tightly coupled slots cover the full azimuthal plane. Tightly coupled slots provide wide bandwidth with minimum gain variation in the endfire direction. Two antenna configurations are presented. The first antenna with eight independent ports is suitable for multiple-input multiple-output (MIMO) systems. The second antenna uses a single excitation port. Eight radiators are sequentially switched using a feed network with p-i-n diodes to cover the whole azimuth plane. Prototypes of the antennas are fabricated. Both of them operate over 8.8-11.2 GHz with input matching better than 10 dB and a gain variation within 4.95 dBi ± 0.25 dBi, including the feed loss.

Gain Enhancement of Low-Profile Omnidirectional Antenna Using Annular Magnetic Dipole Directors

An annular array antenna is proposed in this letter. The proposed low-profile antenna produces an enhanced gain with omnidirectional vertically polarized radiation patterns. Center-fed via-shorted circular patch antenna with omnidirectional radiation pattern can be low profile and wide bandwidth but suffers from tilted beam leading to a low gain in the azimuth plane. To improve the azimuth gain, instead of the traditional way of increasing the profile, a low-profile omnidirectional director is exploited, which is basically a passive magnetic dipole consisting of an annular side-coupling open-cavity. Several directors cooperating with the driven element form the proposed antenna, whose working principle is similar to the Yagi–Uda antenna. A prototype with a low profile of 0.11 ${\lambda _0}$ is designed and fabricated. Measured results show that the prototype can realize −10-dB impedance bandwidth of 13% (4.72–5.42 GHz) and gain of 3.72 dBi at 5.34 GHz with good omnidirectivity. Compared with that of the driven element only, the omnidirectional azimuth gain is significantly improved within the bandwidth, with the maximum gain being enhanced from −4.2 to 3.72 dBi at 5.34 GHz. The proposed antenna is designed for a portable 5G sub-6 GHz wireless channel measurement application.

Experimentally Analyzing Diverse Antenna Placements and Orientations for UAV Communications

A vast array of potential applications is emerging for drones and other devices to collaborate from disaster relief and search and rescue missions to smart agriculture and IoT systems. As drones move across multiple altitudes, they must have the ability to communicate across any direction in a three-dimensional (3D) space. However, due to the heterogeneous nature of the drone body and its interaction with the mounted antennas, different antenna positions on the drone can result in variations in the radiation pattern. While there have been a fair number of airborne communication works, few consider the role that antenna positioning has on the resulting transmission along the azimuth and elevation planes. In this work, we study the effects of the drone body and various antenna placements on the radiation pattern and fading of drone-based channels. Through systematic anechoic chamber and in-field measurements, we show that the drone body alters the radiation pattern of the mounted antennas, rendering the common assumption of a constant azimuth radiation pattern invalid. In addition, the body increases polarization mixing of drone-based channels, resulting in significant degradation of the cross-polarization discrimination (XPD). Hence, we propose using effective radiation pattern and XPD values instead of relying on measurements and/or assumptions that disregard drone-antenna interaction. We then analyze the shadowing and losses associated with the drone body for many antenna setups at various elevation angles and show that when mounted on the opposite side from the ground transmitter, shadowing increases with relatively-higher drone elevations. To account for these body-induced effects, we introduce rotational loss that results in better prediction results of the large-scale fading behavior compared to conventional models that neglect these body effects. Then, we analyze the small-scale fading for various antenna setups and show that the Rician K-factor is strongly dependent on elevation for polarization-matched vertical links, while it is approximately flat for cross-polarized links. To do so, we conduct a set of drone-to-drone (DtD) experiments at high altitudes with no surrounding reflectors and compare results to those obtained by our ground-to-drone (GtD) measurements. We find that, while at low elevations the ground can reduce the K-factor by 10 dB, at higher elevations, small-scale fading is dominated by the antennas, not the ground.

Two‐Dimensional Electromechanically Transformable Metasurface with Beam Scanning Capability Using Four Independently Controllable Shape Memory Alloy Axes

AbstractThe advancements in wireless technology, especially in radar detection, where accurate target information is critically needed, have set new standards for antenna subsystems that demand higher gain and full scanning coverage in both the azimuth and elevation planes while maintaining lower cost and design simplicity. The conventional phased array usually requires complex feeding circuitry with large spatial occupancy that renders the system bulky and expensive; therefore, a reconfigurable metasurface may be a suitable alternative. Earlier research outcomes have shown different kinds of reconfigurability in designing metasurfaces for beam steering. Designing electrically reconfigurable metasurfaces using PIN diodes, varactor diodes, etc., is a well‐known approach; however, these methods suffer from poor isolation of switches, limited power handling due to nonlinearities, high cost, and complicated biasing networks. This work proposes a novel electromechanically transformable metasurface working as a beam‐steering surface with a wider tuning range in the azimuth plane and a simplified independent switching mechanism. The incorporation of four shape memory alloy (SMA) actuator springs allows swift movements in eight different directions. The electrical control of the pitches of the four springs oriented along the four different SMA axes enables adequate mechanical transformation of the 2D metasurface to obtain beam coverage capability.

Wideband Beam-Switched Bow-Tie Antenna With Inductive Reflector

A wideband pattern reconfigurable bow-tie antenna on an inductive reflector is presented. The antenna consists of three bow-tie structures printed on an FR-4 substrate and controlled by six p-i-n diodes. The excited bow-tie at each operating state acts as the driven antenna, while the other bow ties act as the parasitic elements. To achieve low profile and high gain with directional radiation, a 5 × 5 metallic mesh-grid structure is designed as an inductive reflecting surface. It is located at a distance of $0.08{\lambda _0}$ (where ${\lambda _0}$ is the wavelength at the lower operation frequency) from the radiator. The antenna is able to steer the radiation pattern at the angles −25°, 0°, and +25° in the azimuth plane. Moreover, it is capable of electronically switching polarization along the diagonal section of the antenna's surface. It has a compact size of $0.6{\lambda _0} \times 0.6{\lambda _0} \times 0.08{\lambda _0}$ , measured fractional bandwidth of 37% at 0.8–1.16 GHz for tilted states, peak measured gain of 9 dBi, and maximum measured front-to-back ratio of 12 dB with ±1 dBi gain variations and ±3° peak pattern's direction variations across the whole bandwidth in all operational states.

The influence of irregular terrain on infrasonic propagation in the troposphere.

The relations describing the reflection of three-dimensional acoustic ray paths impinging on a non-flat surface are derived and used to approximate the propagation of infrasonic signals over irregular terrain in the geometric limit. The influence of non-flat ground is strongest for those paths that reflect off the surface multiple times, such as those in the tropospheric waveguide; however, notable differences in source and receiver elevations for stratospheric and thermospheric paths can produce notable differences in travel times and arrival amplitudes. The interaction of ray paths with topographical features is investigated using a simple hill to demonstrate the impact of topography on propagation within an azimuthal plane, as well as cases in which the ground surface interaction deflects the path out of the azimuthal plane. Finally, broadband waveform predictions are compared with observations for an event in the western U.S., and a statistical analysis of scattering losses due to interaction with topography in the limit of geometric acoustics is used to improve the agreement between predicted and observed infrasonic signals.

Electronically Controlled Beam Steerable Dual-Band Star-Shaped DRA for UAS and Wi-Fi Data Link Applications

This communication presents a low-cost dielectric resonator antenna (DRA) with beam steering capability in the ${S}$ - and ${C}$ -bands. A centrally fed star-shaped DRA (SDRA) is placed on a circular substrate with backside metallization. Four folded metallic parasitic strips are placed at each corner of the SDRA and grounded via four RF switches. The switches are controlled by an automated microcontroller circuit. It steers the beam in the entire azimuth plane. The antenna has multiple switching modes to carry out basic operations like searching and tracking in unmanned aircraft system (UAS) application. In basic debug mode, all RF switches are kept OFF or ON to check the working state of the antenna. In searching cum tracking (SCT) mode, the RF switches are used to steer the beam and to obtain bidirectional or unidirectional beam. The average peak gain of the antenna in SCT mode is more than 6 dBi. In basic mode, the antenna has a peak gain of ≈3.5 dBi. The measured results validate the beam steering concept.

Wideband 23.5–29.5-GHz Phased Arrays for Multistandard 5G Applications and Carrier Aggregation

This article presents a 23.5–29.5-GHz $8\times 8$ phased array for wideband multistandard applications. The array is based on wideband high-performance $2\times 2$ transmit/receive (TRX) quad-beamformer chips with 6 bit of phase control and 8 bit of gain control. The antenna is designed using a stacked-patch structure combined with a two-stage impedance matching network to enhance its bandwidth. The $8\times 8$ phased array achieves an effective isotropic radiated power (EIRP) of 54.8 dBm at P1dB with a 3-dB bandwidth of 23.5–30.5 GHz and can scan to ±60° in the azimuth plane and +/40° in the elevation plane with excellent patterns with a single-point calibration at 27 GHz. Measured error vector magnitude (EVM) for a 64-QAM 200 and 800-Mbaud waveforms result in a system EVM of 5% (−26 dB) in the TX mode at an average EIRP of 46–47 dBm at 24.5–29.5 GHz. Also, the wideband array is capable of 16-QAM 24-Gb/s links with an EVM <16% over all scan angles. An interband carrier aggregation (CA) system is also demonstrated with the wideband array using 200-Mbaud 64-QAM waveforms with 25- and 29-GHz carriers. The phased-array phase and amplitude settings are chosen such that the 25- and 29-GHz waveforms are radiating simultaneously at the same angle with low scan loss, resulting in an efficient system. Also, the out-of-band third-order intermodulation products generated by the power amplifier on each element are filtered out by the antenna. CA measurements with up to 50° scan angles are demonstrated with low EVM. To the best of our knowledge, this is the first demonstration of CA in millimeter-wave fifth-generation (5G) systems.

Design of a beam steering antenna array using 8x8 butter matrix for indoor positioning system

ABSTRACT This paper proposes a 5 GHz beam steering antenna array (BSAA) based on 8 × 8 Butler Matrix for Indoor Positioning System (IPS). The main beam of BSAA is narrow in azimuth plane with 12° of beam-width while the beam-width in elevation plane is 50°-120°. The steering angle of BSAA in azimuth plane is 108° with eight beams at −52°, −37°, −20°, −8°, +9°, +25°, +40°, +56°, and the peak gains of 7.8 dBi – 11 dBi. The wide beam-width in elevation plane helps to increase the positioning area of BSAA. Also, the narrow beam-width in azimuth plane allows improving the accuracy of IPS.

A Low-Profile High-Gain Slotted Waveguide Antenna Array With Grooved Structures

This letter reports the development of a low-profile and high-gain slotted waveguide antenna array, aiming the FR2 5G frequency range and operating in the 26 GHz band. The proposed array relies on 27-sloped slots, positioned onto the WR28 standard waveguide broadside wall with six pairs of metal grooved structures placed parallel to its axis. Experimental results demonstrate the achievement of 3.41% fractional bandwidth from 25.88 to 26.78 GHz, 27.7 dBi gain and half-power beamwidths in the azimuth and elevation planes equal to 10° and 3°, respectively. The use of metal-grooved structure realizes a gain enhancement of 9 dB, and results in a high-gain antenna array, which is based on a very simple and unique excitation.

Continuous angular control over anisotropic photoemission from isotropic gold nanoshells.

A variety of applications rely on the efficient generation of hot carriers within metal nanoparticles and charge transfer to surrounding molecules or materials. The optimization of such processes requires a detailed understanding of excited carrier spatial, temporal, and momentum distributions, which also leads to opportunities for active optical control over hot carrier dynamics on nanometer and femtosecond scales. Such capabilities are emerging in nanoplasmonic systems and typically rely on tuning optical polarization and/or frequency to selectively excite one or more discrete hot spots defined by the particle geometry. Here, we introduce a unique case in which hot electron excitation and emission distributions can instead be continuously controlled via linear laser polarization in the azimuthal plane of a gold nanoshell supported on a substrate. In this configuration, it is the laser field that breaks the azimuthal symmetry of the supported nanoshell and determines the plasmonic field distribution. Using angle-resolved photoelectron velocity map imaging, we find that the hot electrons are predominantly emitted orthogonal to the nanoshell dipolar surface plasmon resonance axis defined by the laser polarization. Furthermore, such anisotropic emission is only observed for nanoshells, while solid gold nanospheres are found to be isotropic emitters. We show that all of these effects are recapitulated via simulation of the plasmonic electric field distributions within the nanoparticle volume and ballistic Monte Carlo modeling of the hot electron dynamics. These results demonstrate a highly predictive level of understanding of the underlying physics and possibilities for ultrafast spatiotemporal control over hot carrier dynamics.

Acoustic feedback loops for screech tones of underexpanded free round jets at different modes

Abstract