Liste des documents
Structural properties of ZnO thin films deposited by spin-coating method
ZnO thin films are deposited on the glass substrates by sol–gel spin coating technique by varying the concentration of the sol. X-ray diffraction (XRD) and scanning electron microscopy (SEM) analysis were used to investigate the effect of sol concentration on the crystallinity and surface morphology of the films. X-ray diffraction showed that ZnO films were polycrystalline and have the hexagonal structure. The crystallites are preferentially oriented with (002) and the appearance of only (002) c-axis orientation for precursor concentration at 0.1 M. Voir les détails
Mots clés : ZnO, Thin films, sol-gel, concentration
Two-Port MIMO Cylindrical Dielectric ResonatorAntenna For LTE Systems
In this paper, a single cylindrical dielectric resonatorantenna (CDRA) is designed and proposed for multi-input multioutput(MIMO) wireless communications. The proposed antennais excited from two ports and operated around the samefrequency 1.9 GHz, suitable for the 33 and 35 LTE bands. Theproposed design exhibits high isolation between the two ports,with a transmission coefficient less than -35 dB. Theelectromagnetic analysis is carried out using CST microwavestudio and HFSS software. The numerical results, obtained fromsimulation, show a good agreement in terms of S-parameters andradiation patterns. Voir les détails
Mots clés : cylindrical dielectric resonatorantenna (CDRA), multi-input multioutput(MIMO)
3D-FDTD Analysis of Rectangular Printed Monopole Antenna for UWB Applications
This paper presents numerical study of ultrawideband(UWB) patch antenna using both the FiniteDifference Time Domain (FDTD) method and Ansoft HFSSSoftware. The patch antenna, which consists of a rectangularmonopole, is fed by microstrip line and operates from 3 to 10.9GHz, covering the UWB frequency band. The numericalresults, obtained from computed FDTD model and HFSSsimulation, are given and compared in terms of reflectioncoefficients and radiation patterns, and show good agreements. Voir les détails
Mots clés : Monopole antenna, FDTD method, UWB applications.
Rectangular Dielectric Resonator Antenna Array for 5.8GHZ WLAN Applications
In this paper, design of two rectangular dielectricresonator antenna (DRA) array is presented for wireless localarea networks (WLAN) applications (in the dual frequencyrange 5.15-5.35 GHz and 5.72-5.85 GHz).The DRA array isexcited by microstrip feed line through a single slot located inthe ground plane.The numerical analysis is carried out based on the finitedifferencetime-domain (FDTD) method. The numerical resultsin term of return losses and radiation patterns of the dielectricresonator (DR) antenna operating in TE111 mode are presentedand compared with those of a commercial electromagneticsoftware HFSS. A good agreement between the two simulatedresults was obtained. Voir les détails
Mots clés : Rectangular DRA array, wireless local area network (WLAN), FDTD method
Numerical Analysis of a Microstrip MIMO Antenna Array
In this paper, we present a simulation anddesign of a microstrip MIMO antenna array. The basic configuration is a microstrip patch antennas consist of ametallic patch on one side of the dielectric substrate with aground plane on the other side. The antenna system consists of2x4 radiating elements of similar geometry printed on asubstrate. The designed antenna is excited using the microstripfeeding .The theoretical analysis is based on the finitedifferencetime-domain (FDTD) method. In these analyses thecharacteristics of the MIMO antenna arrays are presented interms of return loss, mutual coupling, gain and radiationpatterns. The proposed antenna is simulated by using HighFrequency Structure Simulator (HFSS). The designed antennais suitable for MIMO systems operating for several WLANapplications. Voir les détails
Mots clés : Microstrip antenna, MIMO system, Resonant Frequency, Radiation Pattern, FDTD Method.
Ultra-Wideband Antenna Integrated with Dual-Band Dielectric Resonator
In this paper, we proposed a novel integrated ultrawideband(UWB) monopole antenna with dual-band antenna.The antenna consists of planar rectangular with semi-ellipticalbase and a rectangular dielectric resonator (DRA) with dualbandoperation. Both of them are excited via coplanar waveguide(CPW) lines. The numerical results show that the planarmonopole provides a -10dB impedance bandwidth between 2GHzand 12 GHz which largely covers the entire UWB spectrum, andthe rectangular DRA operates at two bands; 5.7-6.2 GHz and 8.2-9.7 GHz. The electromagnetic analysis is carried out using CSTmicrowave studio and HFSS software. The numerical results,obtained from simulation, are given and compared in terms of Sparameters and radiation patterns. Voir les détails
Mots clés : CPW-fed line, dielectric resonator antenna (DRA), Dual-band antenna, Integrated antennas, UWB antenna.
Performance Evaluation of Omni-Directional Circular UWB Disc Antenna Conformed on a Cylindrical Surface
The cylindrical geometry can offer certain desirable antenna characteristics that are not provided by planar elements. In this paper a conformal omni-directional circular disc antenna which is mounted on a cylindrical surface feeding by a microstrip line is presented and proven to operate equally well compared to its planar rival. The return losses and the radiation pattern characteristics of the proposed antenna are studied using the commercially available electromagnetic software CST studio suiteTM , and high frequency structure simulator HFSS. Compared with the planar shape and the cylindrical conformal antenna existing, the proposed structure possesses an important wideband which is needed for many wearable electronics applications. Voir les détails
Mots clés : Conformal antenna, UWB antenna, CST simulator, HFSS simulator.
Experimental Investigations of an Omni-directional Dielectric Resonator Antenna for UWB Systems
In this paper, a new dielectric resonator antenna(DRA) is presented and investigated for ultra wideband (UWB)applications. The UWB antenna has a U-shape and excited by amicrostip fed monopole. The proposed antenna was simulatedand designed using two electromagnetic simulators. To validateour design, a prototype antenna was fabricated and measured.From the measurements, the U-shaped DRA has a 117.6 %impedance bandwidth (from 2.94 GHz to 11.34 GHz, for returnloss below -10 dB, largely covering the UWB spectrum band).Moreover, the proposed antenna provides an omni-directionalradiation pattern. With these features, the present antenna canbe used in ultra-wideband wireless systems. Voir les détails
Mots clés : Dielectric Resonator Antennas, Measurements, Radition Pattern, UWB applications.
Hybrid Shape Descriptors for an Improved WeldDefect Retrieval in Radiographic Testing
In this paper, four region-based shape descriptors well reported in the literature are used to characterize weld defect types ofcrack, lack of penetration, porosity and solid inclusion, usually encountered in radiographic testing of welds. The rectangularity and the roundness in the geometric descriptor (GEO) are used in order to propose anhybridization algorithm so that the hybrid descriptor issued from GEOand each of the other descriptors becomes more discriminant in suchapplication where, due to bad radiographic image quality and weld defect typology, the human film interpretation is often inconsistent andlabor intensive. According to the results given in the experiments, theefficiency of the proposed hybrid descriptors is confirmed on the welddefects mentioned above where, the retrieval scores are significantly improved compared to the original descriptors used separately. Voir les détails
Mots clés : Weld decfec, radiography, shape descriptor, hybridization
NUMERICAL STUDY OF THE PROPAGATION OF TWO CHIRPED VECTOR SOLITONS IN BIREFRINGENT OPTICAL FIBERS WITH VARIABLE COEFFICIENTS
In this work, we study numerically the propagation of two chirped optical vector solitons in birefringent optical fibers with variable coefficients using the compact split step Padé scheme (CSSPS). In the case of one managed chirped vector soliton, a negative chirp makes the vector soliton broadening, while; a positive chirp leads to a vector soliton compression. The effect of the chirp on the vector soliton temporal width of an amplification system (σ> 0) is greater than that in a loss system (σ< 0). The evolution of two managed chirped vector solitons is submitted not only to the effect of the chirp, but also to the interaction between the adjacent vector solitons. In all the cases, the energy of each managed chirped vector soliton is conserved. Voir les détails
Mots clés : vector solitons, chirped solitons, birefringent optical fibers, compact split step Padé scheme, coupled higher-order nonlinear Schrodinger equations with variable coefficients, temporal waveform.