Mohamed Latrach

Hybrid rectenna and monolithic integrated zero-bias microwave rectifier

In this study, we have developed a hybrid sensitive rectenna (rectifier + antenna) system at 2.45 GHz. To achieve this system, we have first optimized and validated a zero-bias microwave sensitive rectifier using commercial Schottky diodes. We have then optimized and achieved a 2times2 patch antenna array, which is associated to the microwave rectifier in order to validate the rectenna system, where an RF-dc conversion efficiency of 56% has been observed experimentally. In order to minimize the rectenna dimensions, we have conducted a study using the OMMIC ED02AH 0.20-mum GaAs pseudomorphic high electron-mobility transistor process to develop and achieve a monolithic rectifier at 2.45 GHz with RF-dc conversion efficiency of 65%

Theoretical investigation of a circular patch antenna in the presence of a left-handed medium

The influence of a left-handed medium (LHM) on the performances of a circular patch antenna is quantified numerically. For this, a homogenization procedure of the LHM is carried out in order to design the patch antenna at a suitable frequency where the losses of the LHM are low. From the first results obtained, it is noted that in the presence of the LHM, the antenna is more directive and has a higher gain.

Design and experiment of RF rectifiers for wireless power transmission

This paper presents the design and experiment of series mounted diode rectifier and single stage voltage doubler rectifier at 2.45GHz for applications involving microwave power transmission. Input matching circuit and harmonics filtering at both the input and output have been optimized for high efficiency operation. The series topology is dedicated to low input power conversion. Measurement results show that 40% and 27% RF-DC conversion efficiency are achieved for 0 dBm and -5 dBm input power respectively at 2.45GHz. A maximum efficiency of 54% is obtained for an input power of 12 dBm and a 3V output DC voltage is measured at a 1KΩ DC load when the rectifier is matched to 50Ω. The voltage doubler structure is aimed for high input power conversion and exhibits more than 4V at 2.4GHz for input power above 15 dBm.

Design and optimization of a gsm printed dipole antenna for energy harvesting applications

In this paper the design and optimization of a GSM printed dipole antenna for energy harvesting is presented. A very small reflector is placed behind the antenna to increase its gain. This antenna can be used in indoor or outdoor energy harvesting applications. An interesting characteristic is its planar structure which allowing an easy fabrication with low cost. Simulations and measurements have been carried out using HFSS simulator tool and an anechoic chamber to examine the antenna characteristics as gain and radiation patterns. Comparisons between measurements and simulations are done in order to validate the suggested design.

Circular polarized square patch antenna array for wireless power transmission

Wireless power transmission is a process that takes place in any system where electrical energy is transmitted from a power source to an electrical load without a wired connection. Wireless transmission is ideal in cases where instantaneous or continuous energy transfer is needed, but interconnecting wires are inconvenient, hazardous, or impossible. Antenna has become the most vital element in any RF system due to its capability as a radio wave transceiver. A properly designed antenna is desirable to ensure efficient transfer of energy. This paper proposes a square patch antenna array 3×3 designed with a circular polarization using slots for wireless power transmission, through radio wave frequency of 2.45GHz. The array is being designed and simulated by using CST microwave software.

Cylindrical dielectric resonator antenna fed by a stair slot in the ground plane of a microstripline

A novel coupling scheme to cylindrical dielectric resonator antenna is proposed and investigated. In particular, coupling to the resonator is achieved by simple slot firstly and a stair slot secondly exited by a microstrip line. The objectives of this change are to maximize the coupling, increase the gain and miniaturize the structure antenna, achieve resonance at the desired frequency. An approximate and quick design approach is given followed by more accurate design and analysis using commercial software. The antenna was fabricated and tested. Measurements match well with simulation results.

Antenna Radiation in Typical Office Environment: Theoretical Modeling and Measurements

The increasing deployment of wireless communication systems in indoor environment, with different standards, make necessary the research for a new approach allowing the efficient and accurate prediction of their electromagnetic coverage. It becomes essential to predict the behavior of antennas in the presence of various obstacles for planning the communicating devices in the most efficient way. This paper will present an accurate and efficient electromagnetic indoor propagation modeling, based on the FDTD method taking into account the environmental complexity and the dispersive nature of materials. Numerical results are compared with measurement results, other simulation results obtained by using the commercial software HFSS will be compared and discussed.

Novel low cost compact printed antenna CPW-fed for GSM, GPS and PCS applications

In this paper, a novel study on the design and analysis of a compact printed antenna for multi-band applications are presented. The structure of the entire area is 45×45.5 mm2 and is printed on an FR-4 epoxy substrate. It is suitable for GSM/GPS/PCS applications by using an M-shaped antenna which is formed of different arms and an L-shaped shorted strip connected between the feeding line and the ground plane. Simulation results of the antenna input impedance bandwidths for, S11 ≤ (-10) dB, show that it covers the GSM, GPS and PCS bands. Also, a stable radiation pattern and an average antenna “Advanced Design System”. Also, we have conducted another study by using CST-MW to compare the results obtained with ADS which give good agreement between the both EM solvers.

High efficiency low power rectifier design using zero bias schottky diodes

In this paper we present the design of high efficiency low power rectifier for microwave energy harvesting. The proposed circuit is based on a voltage booster formed by a voltage doubler type Latour structure. The circuit topology including parasitic elements and microstrip lines has been studied and optimized for high efficiency energy conversion dedicated to low input power operations (below -10 dBm). Measurement results show 21% and 38% RF-DC conversion efficiencies for, respectively, -20 dBm and -10 dBm input power for 10 KΩ resistor load at 850 MHz. Experimental performances of the rectifier are in good agreement with the simulated ones.

Study of the directivity of a half-loop antenna coupled with magnetic metamaterial cells

The effect of associating Split Ring Resonators (SRR) or C resonators cells with a half-loop antenna is studied. Adding SRRs will shift down considerably the resonance frequency but the directivity will be almost the same. SRRs are good candidate for antenna miniaturization. Adding C resonators will increase more the directivity while the frequency shifting is not as important as with SRR cells. With a ground plane of 10 cm × 10 cm, two cells of C resonators coupled with a half-loop antenna can have a directivity of 7.35 dB at 920.4 MHz. The ground plane can be increased to get better performances.