Planar Pattern Research Articles

Azimuth Null-Reduced Radiation Pattern, Ultralow Profile, Dual-Wideband and Low Passive Intermodulation Ceiling Mount Antenna for Long Term Evolution Application

An ultralow profile, dual-wideband and low passive intermodulation (PIM) in-building ceilingmount antenna for long term evolution (LTE) distributed antenna system (DAS) application is presented. The proposed antenna was designed based on asymmetrical dipole concept having a ground plane with an inclined feeding edge to achieve wideband characteristic and reduced null radiation pattern in the azimuth plane when oriented horizontally. Various dipole and monopole design approaches are presented to give an insight into the typical elevation dipole-liked radiation pattern in the azimuth plane when oriented horizontally to achieve ultralow profile feature. The proposed antenna improves from a simple rectangular monopole to a newly innovated design with off-center feeding location and radiating elements by implementing new design features, e.g. having variation between edges of the radiator and ground plane, slots within monopole radiator and ground plane and inclination of the feeding edge of the ground plane. These additional features enable the proposed design to have a good compromise between the azimuth plane radiation pattern and impedance matching. A production-quality prototype was fabricated to ensure the best PIM performance is achievable. The performance of the prototype was measured. The antenna offers dual-wideband characteristic covering most of the LTE frequency ranges of 698-960MHz and 1350-3800MHz. The passive intermodulation levels that measured for both 700MHz and 1920MHz bands are better than -150 dBc at carrier input of 2 × 20 Watts.

Two-dimensional computational method for generating planar electrode patterns with enhanced volumetric electric fields and its application to continuous dielectrophoretic bacterial capture.

An array of microfabricated interdigitated electrodes (IDEs) is one of the most commonly used forms of electrode geometry for dielectrophoretic manipulation of biological particles in microfluidic biochips owing to simplicity of fabrication and ease of analysis. However, the dielectrophoretic force dramatically reduces as the distance from the electrode surface increases; therefore, the effective region is usually close to the electrode surface for a given electric potential difference. Here, we present a novel two-dimensional computational method for generating planar electrode patterns with enhanced volumetric electric fields, which we call the "microelectrode discretization (MED)" method. It involves discretization and reconstruction of planar electrodes followed by selection of the electrode pattern that maximizes a novel objective function, factor S, which is determined by the electric potentials on the electrode surface alone. In this study, IDEs were used as test planar electrodes. Two arrays of IDEs and respective MED-optimized electrodes were implemented in microfluidic devices for the selective capture of Escherichia coli against 1 μm-diameter polystyrene beads, and we experimentally observed that 1.4 to 35.8 times more bacteria were captured using the MED-optimized electrodes than the IDEs (p < 0.0016), with a bacterial purity against the beads of more than 99.8%. This simple design method offered simplicity of fabrication, highly enhanced electric field, and uniformity of particle capture, and can be used for many dielectrophoresis-based sensors and microfluidic systems.

Three Dimensional Image-Based Radar Cross Section Extrapolation via Planar Projective Transforms

Conventional radar cross section (RCS) measurements require far-field or compact-antenna-test-range (CATR) conditions, which have strict restrictions and high implementation costs. By contrast, RCS extrapolation methods in the near zone are more convenient and practical, which become the research emphasis in recent years. This paper presents a novel RCS extrapolation method based on the combination of near-field 3D synthetic aperture radar (SAR) technique and planar projective transforms (PPT) algorithm. Firstly, to extract the target’s reflectivity distribution, we apply near-field 3D SAR imaging and obtain 3D near-field RCS (NFRCS) images. Secondly, to meet the requirement of RCS measurements, we derive a novel correction factor used to precisely expand 3D NFRCS images. Finally, we extrapolate the plane-wave responses in the azimuth-vertical dimensions, which presents as planar patterns. The proposed method utilizes the complete 3D image-based information to overcome the inherent constraints of classical RCS extrapolation methods on application scenarios, which has the advantages of broad applicability and high flexibility. The detailed derivation and implementation of this method are described in this paper. The simulation and experiment results verify that the proposed method can provide the equivalent CATR result within ±11° azimuth and elevation angles, and it is applicable to precisely measuring the point, surface, and complex scatterers.

Evaluation of heart rate dynamics during meditation using Poincaré phase plane symbolic measures

Meditation has long been known to affect human physiology which is mediated through autonomic nervous system. The main objective of this study was to assess dynamic changes in cardiac inter-beat intervals and autonomic nervous system during meditation hypothesising that Poincare plots in conjunction with symbolic dynamics can lead to better understanding of the dynamics of the underlying physiological mechanisms. The Poincare phase plane standard descriptors can measure only linear gross variability of the heart rate time series. Moreover, these descriptors exhibit limitations where the occurrence of nonlinear behaviour may be responsible to distinguish the phase plane patterns. We captured the changes in Poincare phase plane patterns resulting from nonlinear processes, during two meditation techniques, employing two complexity measures, symbolic dynamics entropy and forbidden words, which are appropriate to distinguish between the two states. Findings show that symbolic dynamics entropy, also a marker of parasympathetic activity, reveals that during premeditation state, there is parasympathetic dominance while during meditation state there is sympathetic dominance in both the meditation techniques. We also show the presence of nonlinear deterministic structures in the meditation inter-beat interval time series and appropriateness of the application of our nonlinear approach through surrogate data analysis.

Tiles and Identity by Pattern Classification

Walled tiles can be figurative or patterned. Whereas the figurative tiles can better be described by theme or author, tile patterns are traditionally classified using more abstract rules that describe either the motif or the pattern itself. In this paper, we present a traditional mathematical classification of plane patterns, the Washburn and Crowe Algorithm, and use it to identify or distinguish tile patterns. We present a complete mathematical classification of the tile patterns present in all places of public access in the Almada region and show how this classification can help recover damaged tiled walls and floors, in order to preserve our heritage. We extend this mathematical analysis to 20th century patterns and quasipatterns, hoping to show that this classification can add to our knowledge of the identity of these patterns.

Improvement of 60 GHz Transparent Patch Antenna Array Performance Through Specific Double-Sided Micrometric Mesh Metal Technology

This paper presents the performance of optically transparent 4 × 2 microstrip patch antenna arrays operating at 60 GHz and made from double-sided micrometric mesh metal layers. A high level of optical transparency (higher than 80%) over the entire visible light spectrum coupled with a sheet resistance lower than 0.5 ohm/sq of the mesh metal films are achieved. Microwave performance of the transparent antenna arrays has been performed from two different mesh ground plane patterns and compared with those of an opaque antenna array made of double-sided continuous metal films. A gain value equal to 13.6 dBi at 58.0 GHz has been recorded, against 15.6 dBi at 59.7 GHz for the opaque antenna array. The influence of the mesh structure and mesh parameters of the ground plane is investigated and discussed. INDEX TERMS Micrometric metal mesh, Microstrip antenna arrays, Millimeter wave antenna, Optically transparent antenna

Trochoidal patterns generation using generalized consensus strategy for single-integrator kinematic agents

This article studies the trochoidal pattern formation in multi-agent system. Single integrator kinematic agents are considered and the trajectories of the agents are controlled to resemble trochoidal patterns. It is shown in the recent literature that the linear consensus strategy can be extended to obtain such patterns in 2D planes under undirected or cyclic graph topology. Here, we further generalize the linear consensus law (1) to achieve such patterns under any graph network topology and (2) to extend the pattern formation in a 3D plane. Since the trochoidal patterns are 2D curves, the proposed control law allows us to specify the 2D plane in the 3D space on which the pattern will be formed. We find the conditions for pattern formation by appropriately placing the eigenvalues of the system. These patterns are not only aesthetically appealing but can also be used in applications such as like search, exploration or surveillance. The results are validated in simulation and are also demonstrated using a group of mobile robots.

Detection and analysis of spatiotemporal patterns in brain activity.

There is growing evidence that population-level brain activity is often organized into propagating waves that are structured in both space and time. Such spatiotemporal patterns have been linked to brain function and observed across multiple recording methodologies and scales. The ability to detect and analyze these patterns is thus essential for understanding the working mechanisms of neural circuits. Here we present a mathematical and computational framework for the identification and analysis of multiple classes of wave patterns in neural population-level recordings. By drawing a conceptual link between spatiotemporal patterns found in the brain and coherent structures such as vortices found in turbulent flows, we introduce velocity vector fields to characterize neural population activity. These vector fields are calculated for both phase and amplitude of oscillatory neural signals by adapting optical flow estimation methods from the field of computer vision. Based on these velocity vector fields, we then introduce order parameters and critical point analysis to detect and characterize a diverse range of propagating wave patterns, including planar waves, sources, sinks, spiral waves, and saddle patterns. We also introduce a novel vector field decomposition method that extracts the dominant spatiotemporal structures in a recording. This enables neural data to be represented by the activity of a small number of independent spatiotemporal modes, providing an alternative to existing dimensionality reduction techniques which separate space and time components. We demonstrate the capabilities of the framework and toolbox with simulated data, local field potentials from marmoset visual cortex and optical voltage recordings from whole mouse cortex, and we show that pattern dynamics are non-random and are modulated by the presence of visual stimuli. These methods are implemented in a MATLAB toolbox, which is freely available under an open-source licensing agreement.

Planar Pattern Switchable Antenna Using Phase Reconfigurable Synthesized Transmission Lines

A new planar pattern switchable antenna is presented in this letter. The phase reconfigurable synthesized transmission line (PRSTL), capable of serving as a 1 bit phase shifter with the aid of varactor diode, is integrated into the feed network as the switching element. By changing the electrical lengths of the PRSTLs, the weighting of the vertical and horizontal current components on the radiator is controlled accordingly, hence, enabling the pattern switchability. Based on the proposed concept, an exemplum with four operating states was designed and fabricated. The measured results show that the radiation can be switched among four states, i.e., end-fire, omnidirectional, and tilted angles of 60° and 120° in the azimuth plane. The efficiency is higher than 61.4%, while the dc power consumption is less than 3.3 μ W in all switching states.

Flow fluctuation induced by coaxial plasma device at atmospheric pressure

The flow structure and velocity fluctuation generated downstream from coaxial geometry dielectric-barrier-discharges are investigated at atmospheric pressure. The discharges are characterized using in-situ electrical measurements and optical diagnostics. Both streamers and glow-like discharges are detected in each alternating-current cycle. The flow structure is temporally and spatially resolved using tracer particles, and vortices are visualized in planar velocity distribution patterns. The flow upstream of the discharge is laminar; however, we discover that the spectrum of downstream fluctuation velocity exhibits a nearly Kolmogorov −5/3 slope, which is a typical feature for high Reynolds number turbulent flows. Based on the electron density measured through a line-ratio method, the dimensionless electrical body force derived from the Navier-Stokes equation is estimated to illustrate the generation of Reynolds stress. It is found that although less than 0.1% of the discharge power is converted into the fluctuation kinetic energy, the electrical body force rather than Joule heating plays a dominant role in flow fluctuation.

A low‐profile printed antenna for unidirectional beam pattern

AbstractA low‐profile antenna with an antenna gain of 6.80 dBi at 8.40 GHz is presented. This antenna radiates vertical polarization with a unidirectional beam pattern in the horizontal plane which is parallel to the ground plane. Furthermore, a monopole array antenna model is used for verification of the antenna mechanism.

Efficient and Sensitive Electrically Small Rectenna for Ultra-Low Power RF Energy Harvesting

A new electrically small antenna with size ka = 0.415 is presented, fabricated and measured in this work. This is intrinsically matched to 50 Ω, has omni-directional and linear-polarized radiation pattern in the horizontal plane with maximum directivity of 1.75 dBi and simulated radiation efficiency of 93%. The antenna in combination with a low-complex and co-planar rectifier with one single diode forms a high efficient and sensitive electrically small rectenna with ka = 0.53 at 868 MHz (UHF RFID-band in Europe). The latter has measured efficiency 22.5% for −19 dBm power input and sensitivity of −44 dBm (or equivalently 0.00028 μW/cm2 power density), while at 2.25 μW/cm2 is able to supply continuously, i.e., without a boost converter or use of any energy tank, a small electrical device with 118 μW. In order to increase the dc output voltage and the delivered dc power to the load for lower power density levels, rectenna-array configuration is exploited. Application to batteryless, backscatter wireless sensor node powering is discussed. Specifically, for a power density of 0.1237 μW/cm2 the RF energy harvesting system delivers 172 μW at 2.85 V every 22.5 s.

Fiber Embroidery of Self-Sensing Soft Actuators.

Natural organisms use a combination of contracting muscles and inextensible fibers to transform into controllable shapes, camouflage into their surrounding environment, and catch prey. Replicating these capabilities with engineered materials is challenging because of the difficulty in manufacturing and controlling soft material actuators with embedded fibers. In addition, while linear and bending motions are common in soft actuators, rotary motions require three-dimensional fiber wrapping or multiple bending or linear elements working in coordination that are challenging to design and fabricate. In this work, an automatic embroidery machine patterned Kevlar™ fibers and stretchable optical fibers into inflatable silicone membranes to control their inflated shape and enable sensing. This embroidery-based fabrication technique is simple, low cost, and allows for precise and custom patterning of fibers in elastomers. Using this technique, we developed inflatable elastomeric actuators embedded with a planar spiral pattern of high-strength Kevlar™ fibers that inflate into radially symmetric shapes and achieve nearly 180° angular rotation and 10 cm linear displacement.

Miniaturised triple‐band antenna loaded with complementary concentric closed ring resonators with asymmetric coplanar waveguide‐fed based on epsilon negative transmission line

This study presents an open-ended triple-band miniaturised metamaterial (MTM) inspired antenna based on the epsilon negative-transmission line (ENG-TL). The zeroth-order resonance (ZOR) and first-order resonance (FOR) characteristics are implemented using the ENG-TL theory. The proposed MTM antenna consists of rectangular and square-shaped complementary concentric closed ring resonator (CCCRR) in the left and right half of the asymmetric coplanar waveguide (CPW) ground plane, respectively. The CCCRR generates an extra coupling capacitance and inductance, which help for improving the gain at ZOR mode and better impedance matching at higher-order mode. The resonance characteristic of the antenna is controlled by the shunt elements due to its open-ended boundary condition. The proposed triple-band MTM antenna offers measured -10 dB impedance bandwidths of 8.54% (1.12-1.22 GHz), 10.25% (2.22-2.46 GHz) and 35.75% (2.94-4.22 GHz). All these three bands show good impedance matching with appropriate gain and high radiation efficiency and also having an omnidirectional pattern in the xz- plane and dipolar type pattern in the yz -plane. The designed antenna shows an overall dimension of 0.11 λ 0 × 0.11 λ 0 × 0.006 λ 0 at ZOR frequency (1.16 GHz).

On the Kinematics of Vehicles Relevant to Conflict Detection and Resolution

The paper presents methods to determine the time, positions, and distance of closest approach for two vehicles following arbitrary trajectories in two or three dimensions. The distance of closest approach of two vehicles following arbitrary curved trajectories is determined by two conditions: (i) the relative velocity must be orthogonal to the relative position in order for the distance to be a nonzero extremum; (ii) the radial acceleration including centripetal terms must have a direction that increases the separation for the extremum to be a minimum. This theorem on the distance of closest approach simplifies in the case of uniform motion along rectilinear trajectories. Three examples are given: (i) the two-dimensional motion of surface vehicles changing the velocity of one of them so as to enforce a given minimum separation distance; (ii) the three-dimensional motion of two aircraft, one flying horizontally and the other climbing, changing the vertical velocity of the latter to ensure a minimum separation distance set “a priori”; (iii) the case of an aircraft flying with constant velocity in a straight line so that its closest approach to another aircraft flying in a circular holding pattern in the same plane occurs at a given time chosen “a priori”.

Rhabdomyolysis revisited

The objective is to evaluate the magnetic resonance imaging (MRI) findings in rhabdomyolysis in detail and determine their correlation with the development of peripheral neuropathy.Magnetic resonance images for 23 patients with confirmed rhabdomyolysis with (n = 11) or without (n = 12) peripheral neuropathy were retrospectively reviewed for the signal intensity on T1- and T2-weighted images, intramuscular hemorrhage, enhancement pattern, shape and margin in the longitudinal plane, edema in the deep fascia and overlying subcutaneous layer, multiplicity, and bilateral limb involvement. The collected data were statistically analyzed and the relationship between the imaging findings and the development of peripheral neuropathy was determined.Abnormal signal intensities on T1- or T2-weighted images were observed for all patients except one. Fourteen patients (60.9%) showed intramuscular hemorrhage. Stippled enhancement (11/23; 47.8%) was the most common enhancement pattern. Nineteen patients (86.4%) showed a well-defined rectangular shape with a ragged margin in the longitudinal plane. The affected muscle volume usually increased (17/23; 73.9%), with edema in the deep fascia and the overlying subcutaneous layer (13/23; 56.5%). Multiplicity within a muscle, compartment, and limb was observed in 7 (31.8%), 18 (81.8%), and 16 (72.7%) patients, respectively. Bilateral involvement was observed in 7 patients (30.4%). Only multiplicity within a compartment showed a statistically significant correlation with peripheral neuropathy development.Common MRI findings in rhabdomyolysis include intramuscular hemorrhage, stippled enhancement, a well-defined rectangular shape with a ragged margin in the longitudinal plane, and multiplicity. Multiplicity within a compartment may be a predictor of the development of peripheral neuropathy.

Analysis of Planar Ornament Patterns via Motif Asymmetry Assumption and Local Connections

Planar ornaments, a.k.a. wallpapers, are regular repetitive patterns which exhibit translational symmetry in two independent directions. There are exactly $17$ distinct planar symmetry groups. We present a fully automatic method for complete analysis of planar ornaments in $13$ of these groups, specifically, the groups called $p6m, \, p6, \, p4g, \,p4m, \,p4, \, p31m, \,p3m, \, p3, \, cmm, \, pgg, \, pg, \, p2$ and $p1$. Given the image of an ornament fragment, we present a method to simultaneously classify the input into one of the $13$ groups and extract the so called fundamental domain (FD), the minimum region that is sufficient to reconstruct the entire ornament. A nice feature of our method is that even when the given ornament image is a small portion such that it does not contain multiple translational units, the symmetry group as well as the fundamental domain can still be defined. This is because, in contrast to common approach, we do not attempt to first identify a global translational repetition lattice. Though the presented constructions work for quite a wide range of ornament patterns, a key assumption we make is that the perceivable motifs (shapes that repeat) alone do not provide clues for the underlying symmetries of the ornament. In this sense, our main target is the planar arrangements of asymmetric interlocking shapes, as in the symmetry art of Escher.

SAR imaging of virtual vegetation based on a 3-D coherent scattering model

ABSTRACTIn this article, we simulate the synthetic aperture radar (SAR) image of virtual trees using an image-processing algorithm based on the radar coherent scattering model. To make simulations much closer to real SAR imaging, the changes of antenna observation angle and frequency bandwidth of SAR are considered in the image processing, and the antenna pattern in the azimuth plane is also taken into consideration in the scattering model. The combination of the scattering model and the image-processing algorithm will contribute to understanding the imaging result of SAR response to forest structures and to optimizing the design of the SAR sensor. Furthermore, a height extraction method from the interferometry of airborne single-pass SAR is used to extract vegetation height. Finally, the scattering amplitude and height images of virtual trees in a stand are simulated. The simulation results demonstrate that the combination of the radar coherent scattering model and the image-processing algorithm provides a reasonable interpretation of the images according to the scattering mechanism.

Beam‐switching millimetre‐wave antenna using cantilever‐based FSSs

A beam-switching antenna for millimetre-wave applications at 30 GHz is presented in this study. The radiation reconfigurability for a cylindrical dielectric resonator antenna (DRA) is obtained by using a cantilever-enabled frequency selective surface (FSS). The proposed cantilever-enabled FSS provides reconfigurable bandpass and band-stop performance with good isolation between them. The investigation of designed FSS is performed using electromagnetic simulation and an array of the proposed FSS unit cell is fabricated and measured using the free-space measurement method, which shows a good agreement with the simulation results. Finally, six panels of the 1 × 5 array of the proposed reconfigurable FSS are arranged in a hexagonal configuration around a cylindrical DRA to obtain a reconfigurable radiation pattern in the azimuth plane. A prototype of the proposed radiation reconfigurable DRA is fabricated and the switching radiation patterns are measured at 30 GHz.

Stress Concentration in Low-Porosity Periodic Tessellations With Generic Patterns of Elliptical Holes Under Biaxial Strain

Stress concentration in porous materials is one of the most crucial culprits of mechanical failure. This paper focuses on planar porous materials with porosity less than 5%. We present a stress-prediction model of an arbitrarily rotated elliptical hole in a rhombus shaped representative volume element (RVE) that can represent a class of generic planar tessellations, including rectangular, triangular, hexagonal, Kagome, and other patterns. The theoretical model allows the determination of peak stress and distribution of stress generated near the edge of elliptical holes for any arbitrary tiling under displacement loading and periodic boundary conditions. The results show that the alignment of the void with the principal directions minimizes stress concentration. Numerical simulations support the theoretical findings and suggest the observations remain valid for porosity as large as 5%. This work provides a fundamental understanding of stress concentration in low-porosity planar materials with insight that not only complements classical theories on the subject but also provides a practical reference for material design in mechanical, aerospace, and other industry.