Octagonal Configuration Research Articles

Compact MIMO UWB antenna integration with Ku band for advanced wireless communication applications

This paper introduces a compact Multiple Input Multiple Output (MIMO) Ultrawideband (UWB) antenna seamlessly integrated with the Ku band, tailored for wireless communication applications. The MIMO antenna employs octagonal radiators, crafted from a tapered microstrip line-fed rectangular patch, etched on an economically efficient FR4 substrate measuring 40 × 23 mm2. The octagonal configuration is achieved by introducing a rectangular patch to the central radiator, while parasitic stubs are strategically employed to mitigate coupling among MIMO elements. The antenna demonstrates an extensive operational bandwidth spanning 3.28–17.8 GHz, covering UWB, extended UWB, and Ku-band spectrums globally allocated for heterogeneous applications. With a peak gain of 4.93 dBi and an efficiency of 95.34%, the proposed MIMO antenna showcases superior performance. Key performance parameters, including a low envelope correlation coefficient (ECC) of 0.003 and a substantial diversity gain (DG) of 9.997 dB, are thoroughly analyzed. Comparative assessments against recent works validate the novelty and potential of the proposed antenna for integration into compact wireless systems. This study underscores the success of the antenna design in achieving a harmonious balance of compactness, wide operational bandwidth, and high performance, positioning it as a promising candidate for diverse wireless communication applications.

Three dimensional flow over elliptic cylinders arrays in octagonal arrangement

A numerical study of flow characteristics around eight elliptic cross-section cylinders in an octagonal configuration is presented. The axis ratio of elliptic cylinder is taken as 1:2. Three spacings between the cylinders (0.07 m, 0.14 m and 0.2 m), two angles of attack (α=0° and α=15°) and two Reynolds numbers (Re=4060 and Re=45800) are considered to investigate the parametric influences. The flow is modelled using three-dimensional large eddy simulation. Simulations are performed by utilizing ANSYS Fluent software. The results comprise of flow patterns and force coefficients (drag and lift). It is seen that both the drag and lift forces acting on the cylinders vary with the spacings values, angle of attack and Reynolds numbers. The lift force peaks at α=15° and Reynolds number 45800. The drag force on the upstream cylinder reaches its peak at α=0° and Reynolds number 4060. It is observed that the drag on the upstream cylinders decreases as the value of the Reynolds number increases. Contours of velocity and subgrid turbulent viscosity are also presented. Moreover, it is concluded from the present study that the effect of change in the Reynolds number on flow characteristics is more significant as compared to the change in the spacing between the cylinders.

Large eddy simulation of flow over square cylinder arrays in an octagonal configuration at subcritical Reynolds numbers

AbstractIn this study, fluid flow over an array of eight, 0.029 m × 0.029 m, square cross‐section cylinders in an octagonal configuration is studied numerically. The mean force coefficients (drag and lift) and the vortex formation characteristics of the array are calculated numerically by utilizing a three‐dimensional large eddy simulation mathematical model for turbulence. The numerical simulation is performed with commercial software ANSYS Fluent 19R1. To investigate the parametric influences, three spacings between the cylinders (0.07, 0.14, and 0.2 m), two array attack angles (0° and 15°), and two Reynolds numbers (4060 and 45 800) are considered. The results comprise flow patterns and force coefficients' variations with Reynolds numbers. The lift force of the downstream cylinder reaches its maximum at α = 15°, and the drag force of the upstream cylinders finds its peak at α = 0°. It is observed through velocity and viscosity contour plots that vortex formation length near the cylinder increases at higher Reynolds number. Velocity vector plots are also presented to show fluid flow behavior near the cylinder. Furthermore, the predicted mean forces on the cylinders are slightly different for different Reynolds numbers, spacings, and angles of attack.

Design and Characterization of an Extremely-Sensitive, Large-Volume Gamma-Ray Spectrometer for Environmental Samples.

A large volume gamma spectrometer was designed and constructed to analyze foodstuffs and environmental samples having low radionuclide concentrations. This system uses eight 11-cm × 42.5-cm × 5.5-cm NaI(Tl) detectors, chosen due to their relatively high sensitivity and availability and arranged in an octagonal configuration. The sensitive volume of the system is ~28 cm in diameter and ~42 cm deep. Shielding consists of an 86-cm × 86-cm square, 64-cm-tall lead brick enclosure with 18-cm-thick lead walls lined by 0.3-cm-thick copper plates. An aluminum top was machined to suspend the detectors within this shield. The shielding reduces background counts by 72% at 100 keV and 42% at 1,000 keV. The positional variability in sensitivity of the well was determined by both simulation and experiment. A 2.1-L volume of nearly uniform sensitivity, varying less than 10%, exists in the well's center. Energy resolutions of 14.6% and 7.8% were measured for Am and Cs, respectively. Energy resolution shows a 0.2% variation for both Am and Cs as a function of position within all regions of the well's central sensitive volume. Dead time was also determined to be less than 35% for all sources measured in the system, the largest of which had an activity of 1,760 kBq. Simulated results for various source geometries show higher counts for smaller samples, especially at lower energies due to less attenuation of low energy photons. Minimum detectable activities were determined for all source energies used, less than 5.1 Bq kg for reasonable background and sample counting times.

UWB Coplanar Waveguide Octagonal Antenna

This paper concerns the design of a new ultra-wideband antenna with an octagonal configuration and reduced size. The prototype has been simulated and designed. It has shown a permissible agreement between simulations and measures and an operation of ultra-wideband from 2.38 to 14 GHz (142 %) for wireless applications.

A 2.3-14 GHz UWB planar octagonal antenna with modified ground plane

This article concerns the design of a new ultra-wideband antenna with an octagonal configuration and reduced size. The prototype has been simulated and designed as a monopole. It has shown a permissible agreement between simulations and measures and an operation of ultra-wideband from 2.3 to 14 GHz (143.55%) for wireless applications. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:474–479, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27342

New UWB antenna design for wireless communications

AbstractThe presented work in this article concerns a new ultra‐wideband antenna design with an octagonal configuration and reduced dimensions. Different prototypes have been simulated and implemented in the form of monopoles. These prototypes have shown an admissible agreement between simulations and measurements and ultra‐wide bands running from 3.1 to 14 GHz for wireless applications. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:692–697, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26666

Synthesis and characterization of phase-purity Cu 9BiS 6 nanoplates

Single crystalline Cu 9BiS 6 nanoplates have been synthesized via a hydrothermal route. The X-ray diffraction (XRD) showed these resultant nanoplates having cubic symmetry with the cell constant of 0.556 nm. The morphology of these nanoplates identified by scanning electron microscopy (SEM) was the hexagonal and octagonal configurations respectively. Microstructure characterized by transmission electron microscopy (TEM) revealed six side surfaces of the hexagonal nanoplate coincident with the {110} lattice planes and the octagonal nanoplate enclosed by the four {100} and four {110} lattice planes. Optical diffuse reflectance measurement demonstrated that these Cu 9BiS 6 nanoplates have a band gap of 1.25 eV.

Large volume CsI(Tl) scintillators for exotic particle search in /sup 90/Zr

The E0 transition of first excited /sup 90/Zr nucleus has been studied with an octagonal configuration of 30 cm length CsI(Tl) scintillators and a strong /sup 90/Sr /spl beta/ source. To study a contribution of yet unknown neutral particles or phenomena in this transition, the precision measurement of even conventional transition processes with electron- and photon pairs is necessary. The rates for these transition modes are substantially small, and the background reduction from the data is of primary importance. Based on the present observation, we introduce somewhat nobel attempt to the efficient rare decay experiment as well as a method for position measurement of low energy /spl gamma/ rays.

Smooth quasi‐homogeneous gridding of the sphere

AbstractWe describe a variational technique for generating smooth quasi‐homogeneous numerical grids covering the sphere. This work extends our earlier studies of non‐standard global grids by relaxing the requirement of conformality to admit a greater degree of homogeneity. The motivation for this extension is to increase the minimum grid distance and thus to enable a larger time step to be used within an Eulerian grid‐point model. The grids described here are specified by balancing terms in a variational principle that penalizes departures of grid‐point density from smoothness and homogeneity. Grids generated by the new procedure are tested in both the cubic and octagonal configurations we have described in our earlier studies. The time‐step restriction is successfully alleviated without significant loss of solution accuracy.

Optimizing short-term plume containment: comparison of well arrangements : Suguino, H H; Peralta, R C Proc Symposium on Geology and Hydrology of Hazardous-Waste, Mining-Waste, Waste-Water and Repositories Sites in Utah, Salt Lake City, 1989P43–50. Publ Salt Lake City: Symposium and Field Conference, 1989 (Utah Geological Association Publication 17)

Abstract Three well configurations were compared in terms of short-term ground-water contaminant plume containment. These include parallel, octagonal and combination systems. Each system had three extraction wells upgradient and three injection wells downgradient of the contaminant plume. For each system, optimal pumping values and resulting potentiometric surface smoothness were computed for a hypothetical plume. Tested models utilized linear programming optimization and simulation via the response matrix method. The octagonal well configuration required less pumping for a pumping period of 8 days, than did the parallel or combination systems. The octagonal configuration resulted in the smoothest potentiometric surface, in terms of difference in final head at observation wells compared with those at the contaminant source.