Horn Antennas Loaded with Metamaterial for UWB Applications

YesIn this paper, a conical horn antenna has been designed for Ultra-Wideband ap-plications by loading its section with a metamaterial. The work aims first to compare results obtained by the wavelet-moment method to a simulation performed using HFSS. Secondly the conical horn is loaded with a very thin layer of metamaterial to enhance the radiation pattern and the bandwidth performance of the conical horn antenna and reduce the size of the antenna. The operating bandwidth of the proposed antenna is in the range of 10{13 GHz. The results obtained from HFSS and moment method are in good agreement.Electronics and Telecommunication

Analysis of the Combinatory Effect of Uniaxial Electrical and Magnetic Anisotropy on the Input Impedance and Mutual Coupling of a Printed Dipole Antenna

The main objective of this work is to investigate the combinatory effects of both uniaxial magnetic and electrical anisotropies on the input impedance, resonant length and the mutual coupling between two dipoles printed on an anisotropic grounded substrate. Three different configurations: broadside, collinear and echelon are considered for the coupling investigation. The study is based on the numerical solution of the integral equation using the method of moments through the mathematical derivation of the appropriate Green's functions in the spectral domain. In order to validate the computing method and evaluated Matlab? calculation code, numerical results are compared with available literature treating particular cases of uniaxial electrical anisotropy; good agreements are observed. New results of dipole structures printed on uniaxial magnetic anisotropic substrates are presented and discussed, with the investigation of the combined electrical and magnetic anisotropies effect on the input impedance and mutual coupling for different geometrical configurations. The combined uniaxial (electric and magnetic) anisotropies provide additional degrees of freedom for the input impedance control and coupling reduction

Analysis of Chiral and Achiral Medium Based Coplanar Waveguide Using Improved Full Generalized Exponential Matrix Technique

In this work, an analytical study of the electromagnetic propagation in a complex medium-based suspended three-layer coplanar waveguide (CPW) is carried out. The study aims at a numerical calculation of the dominant hybrid mode complex propagation constant in the CPW printed on a bianisotropic substrate. The herein considered bianisotropy is characterized by full 3×3 tensors of permittivity, permeability and magnetoelectric parameters. The study is based on the numerical derivation of the Green's functions of such a complex medium in the spectral domain. The study is carried out using the Full Generalized Exponential Matrix Technique based on matrix-shaped compact mathematical formulations. The Spectral Method of Moments (SMoM) and the Galerkin's procedure are used to solve the resulting homogeneous system of equations. The effect of the chiral and achiral bianisotropy on the complex propagation constant is particularly investigated. Good agreements with available data for an anisotropic-medium-based suspended CPW structure are achieved. Various cases of chiral and achiral bianisotropy have been investigated, and particularly, the effect on the dispersion characteristics is presented and compared with cases of isotropic and bianisotropic Tellegen media

Impedance Bandwidth Improvement of a Planar Antenna Based on Metamaterial-Inspired T-Matching Network

In this paper a metamaterial-inspired T-matching network is directly imbedded inside the feedline of a microstrip antenna to realize optimum power transfer between the front-end of an RF wireless transceiver and the antenna. The proposed T-matching network, which is composed of an arrangement of series capacitor, shunt inductor, series capacitor, exhibits left-handed metamaterial characteristics. The matching network is first theoretically modelled to gain insight of its limitations. It was then implemented directly in the 50-Omega feedline to a standard circular patch antenna, which is an unconventional methodology. The antenna's performance was verified through measurements. With the proposed technique there is 2.7 dBi improvement in the antenna's radiation gain and 12% increase in the efficiency at the center frequency, and this is achieved over a significantly wider frequency range by a factor of approximately twenty. Moreover, there is good correlation between the theoretical model, method of moments simulation, and the measurement results

Transparent 2-Element 5G MIMO Antenna for Sub-6 GHz Applications

YesA dual-port transparent multiple-input multiple-output (MIMO) antenna resonating at sub-6 GHz 5G band is proposed by using patch/ground material as transparent conductive oxide (AgHT-8) and a transparent Plexiglas substrate. Two identical circular-shaped radiating elements fed by using a microstrip feedline are designed using the finite element method (FEM) based highfrequency structure simulator (HFSS) software. The effect of the isolation mechanism is discussed using two cases. In case 1, the two horizontally positioned elements are oriented in a similar direction with a separate ground plane, whereas in case 2, the elements are vertically placed facing opposite to each other with an allied ground. In both cases, the transparent antennas span over a −10 dB band of 4.65 to 4.97 GHz (300 MHz) with isolation greater than 15 dB among two elements. The diversity parameters are also analyzed for both the cases covering the correlation coefficient (ECC), mean effective gain (MEG), diversity gain (DG), and channel capacity loss (CCL). The average gain and efficiency above 1 dBi and 45%, respectively with satisfactory MIMO diversity performance, makes the transparent MIMO antenna an appropriate choice for smart IoT devices working in the sub-6 GHz 5G band by mitigating the co-site location and visual clutter issues.This work is supported by the Moore4Medical project, funded within ECSEL JU in collaboration with the EU H2020 Framework Programme (H2020/2014-2020) under grant agreement H2020-ECSEL-2019-IA-876190, and Fundação para a Ciência e Tecnologia (ECSEL/0006/2019)

Phytochemical study of four plants from the family Myrsinaceae

International audienceFour Peruvian plants (Cybianthus magnus, Myrsine latifolia, Myrsine congesta and Myrsine sessiliflora) belonging to the Myrsinaceae family have been studied in search of molecules with antileishmanial activity. From the hydromethanolic extract of three parts of each plant (leaves, stem and roots) 10 compounds were purified and identified. The purification was performed using chromatographic methods (HPLC; semi preparative chromatography) and the structure elucidation was accomplished by 1D, 2D NMR spectra (1H-1H, 13C, DEPT, COSY, HSQC, HMBC). One new compound was isolated and identified as 5-alkylresorcinolglucoside, named Cybianthoside A, from C. magnus. From the other plants, six flavonoids were isolated: (-) catechin, catechin-3-O-rhamnopyranoside , quercetin-3-O-rhamnopyranoside, isorhamnetin-3-O-rhamnopyranoside, quercetin-3-O-arabinopyranoside and quercetin-3-O-arabinofuranoside ; one lignan: lyoniresinol-9'-O-glucopyranoside ; one resorcinol derivative: 12'Z-5-heptadec-12'-enylresorcinol and two chromanes: myrsinoic acid B and myrsinoic B methyl ester. Extracts and fractions were evaluated for their antileishmanial activity but no activity was detected

Etude phytochimique de Poraqueiba sericea.

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Zebiriosides A-P, oleanane saponins isolated by LC-SPE-NMR hyphenation from the roots of Dendrobangia boliviana

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A new 5-alkylresorcinol glucoside derivative from Cybianthus magnus

One new 5-alkylresorcinol glucoside (1) was isolated from leaves of Cybianthus magnus, along with 12 known compounds, isolated from four plants belonging to Myrsinaceae family (2, 3 isolated from C. magnus; 4-7, 10 and 11 isolated from Myrsine latifolia; 4, 8 and 9 isolated from Myrsine sessiflora; 6, 7, 10, 12 and 13 isolated from Myrsine congesta). Their structures were determined on the basis of spectroscopic analysis and by comparison of their spectral data with those reported in the literature. So far, only nine 5-alkylresorcinol glucosides were isolated from leaves of Grevillea robusta. Since resorcinols are known to exhibit strong cytotoxic activity, compounds 1 and 2 were tested against cell lines 3T3, H460, DU145 and MCF-7 for cytotoxicity in vitro and compounds 3-13 were tested for their antileishmanial activity. Compound 2 displayed a strong cytotoxic activity with IC50 values ranging between 22 and 100M for all tested cell lines. Compounds 3-13 were not active against Leishmania amazonensis amastigotes