A Miniature L-slot Microstrip Printed Antenna for RFID

This work presents a miniature microstrip antenna at 2.45 GHz by using the slots technique. This microstrip antenna is fed by a CPW technique and designed for RFID reader system on FR4 substrate. A size reduction equal to 66.6% has been obtained compared to the conventional rectangular microstrip antenna. The total area of the final circuit is 19x31 mm2. The validated antenna has good matching input impedance with a stable radiation pattern, a loss return of -40 dB, and a gain of 1.78 dBi, a prototype of the proposed antenna has been fabricated and measured

Design and Fabrication of the Novel Miniaturized Microstrip Coupler 3dB Using Stepped Impedance Resonators for the ISM Applications

In this work, a novel miniaturized compact coupler using the shunt-stubs artificial transimission lines with high and low impedances is presented. Design of the proposed coupler is accomplished by modifying the length and impedance of the branch lines in the conventional structure with the planar resonators in order to achieve branch line coupler with compact size and improvement of the performances. First part of this work is focusing on the theorical study of the proposed resonators where the equations are obtained. Secondly, the proposed coupler is designed on FR4 susbtrate, and simulated by using the EM Solver (ADS from Agilent technologies and CST microwave studio) in order to operate in the ISM band. The obtained results show good agreement with the simulations and the coupler shows a good perfo6rmance in the hole bandwidth. The size of the proposed coupler is reduced around 50% compared to the conventional design. The last part conerns the fabrication and test of the proposed coupler. The measurement and simulation results are in good agreements

Les déterminants du choix de financement des entreprises par les banques participatives : revue de littérature empirique

L’accès des banques participatives à la scène financière a permis aux entreprises d’avoir de suppléments choix de financement notamment avec le succès qu’ont atteintes, ce choix est orienté par des critères et des déterminants se distinguant d’un contexte à autre. Cet article présente ainsi une synthèse de la littérature des analyses empiriques portant sur cet axe de recherche, depuis les premiers travaux en la matière jusqu’à la date d’achèvement du présent article

1.25 GHz – 3.3 GHz broadband solid state power amplifier for L and S bands applications

The research of a single stage broadband solid-state power amplifier based on ATF13876 transistor, which operates in the frequency ranging from 1.25 GHz ~3.3 GHz is presented in this paper. To achieve the broadband performance of the operating bandwidth, a multi-section quarter wave impedance transformer and an approximate transformation of previously synthesized lumped elements into transmission lines are adopted. With neatly design of broadband matching networks and biasing circuit, excellent matching performances and unconditionally stability are achieved over the whole operating bandwidth with a maximum gain of 17.2 dB. The large signal simulation shows that the proposed circuit reaches a saturated output power of 18.12 dBm with a maximum PAE of 27.55% and a 1-dB compression point at 5 dBm input power level. Considering the wide frequency coverage, the features of the proposed design compares favorably with the contemporary state-of-the-art

A Novel Cpw Low Cost Lowpass Filter Integrating Periodic Structures

In this work, we propose a novel design of a planar CPW lowpass “LPF” filter based on the use of periodic structures. The periodic cells are formed from a rectangular slot repeated periodically. The originality of this work is to develop a new LPF structure which is simple, low cost for fabrication and easy to associate with others microwave planar circuits. The proposed and validated LPF is a compact planar filter structure. The final circuit is simulated and optimized by using two electromagnetic solvers, ADS (Advanced Design System) and HFSS (High Frequency Structural Simulator). After many series of optimization we have validated the final circuit into simulation by using optimization methods integrated into the both solvers, taking into account a high density of meshing in order to cover the whole circuit. The fabricated LPF circuit shows good agreement between simulation and measurement results in term of matching input impedance and insertion loss with a cutoff frequency of 1.25GHz. The entire area of the proposed LPF is 35x31 mm2

A New Dual Band Printed Metamaterial Antenna for RFID Reader Applications

In this paper, we present a new dual band metamaterial printed antenna for radio frequency identification applications. The proposed antenna consists of two L-shaped slot in the radiating element for dual band operation and a complementary split ring resonator etched from the ground plane for size miniaturization. This antenna is designed and optimized by CST microwave studio on FR-4 substrate with thickness of 1.6 mm, dielectric constant of 4.4 and tangent loss of 0.025. A microstrip line with characteristic impedance of 50 ohms is used to feed this antenna. A prototype of the proposed antenna is fabricated to validate the simulation results. The measured and simulated results are in good agreement.

A new design of a microstrip rectenna at 5.8 GHz for wireless power transmission applications

Due to the ever-increasing power demand, the need of electricity and eco-friendly power in every nook and corner of the world, many reaserch topics have been devoted to deal with this problematic. This paper is taking part of the proposed solutions with the presentation of a novel 5.8 GHz rectenna system for wireless power transmission applications. In one hand, a miniaturized 5.8 GHz circular polarized patch antenna has been designed and simulated by using the Advanced Design System (ADS). In the other hand, a rectifier structure has been investigated and optimized by the use of the Harmonic Balance method available in ADS. The circuit is based on 5 HSMS2820 Schottky diodes implemented in a voltage multiplier topology and a load resistance of 1 KOhm. Both of the structures have been validated by simulation and experimental results and good agreement has been concluded

Impacts of Human Body on Antenna Radiation in Indoor Environments : Numerical Modeling and Experimental Validation

International audienceThe presence of human body has an important influence on the wireless communication systems in indoor environments. The need of efficient prediction for such coverage becomes essential. This paper present an efficient electromagnetic indoor propagation modeling, taking into account the presence of human body and the nature of materials of the complex environment, based on the Finite-Difference Time-Domain method. Numerical results are compared with measurement results and show a good agreement

A trade-off design of microstrip broadband power amplifier for UHF applications

In this paper, the design of a Broadband Power Amplifier for UHF applications is presented. The proposed BPA is based on ATF13876 Agilent active device. The biasing and matching networks both are implemented by using microstrip transmission lines. The input and output matching circuits are designed by combining two broadband matching techniques: a binomial multi-section quarter wave impedance transformer and an approximate transformation of previously designed lumped elements. The proposed BPA shows excellent performances in terms of impedance matching, power gain and unconditionally stability over the operating bandwidth ranging from 1.2 GHz to 3.3 GHz. At 2.2 GHz, the large signal simulation shows a saturated output power of 18.875 dBm with an output 1-dB compression point of 6.5 dBm of input level and a maximum PAE of 36.26%

Effect of the magnetic properties of the inclusions on the high-frequency dielectric response of diluted composites

International audienceThe high-frequency permittivity of composites consisting of a lattice of ferromagnetic wires is investigated. Experimental results using free space or coaxial line microwave measurements are reported. It is shown that the dielectric response is strongly dependent on the magnetic properties of the wires. Negative real permittivity is observed over a wide frequency range for wires with circumferential magnetization, while a resonant behavior is observed on wires with an axially magnetized core. In addition, it is shown that a moderate external field can induce large changes in the dielectric response. We prove that the underlying physics of these composites made of oriented magnetic wires is basically the same as the giant magnetoimpedance (GMI) effect. A model based on GMI equations is proposed which predicts this unusual dielectric phenomenon