Majida Fadlallah

Performances of low profile dipole antenna AMC-based surface using metamaterials structures

Artificial Magnetic Conductors (AMCs), a real version of Perfect Magnetic Conductors (PMCs), are widely used to replace surfaces of high impedance. Based on unit cells of Multiple Split-Ring Resonators (MSRRs) that are printed on low-cost dielectric grounded substrate, AMCs are employed as a ground plane for antennas. In this paper, the performance of a low profile dipole antenna positioned above a planar AMC surface is examined. The characteristics of the AMC return loss are initially investigated at the resonant frequency of 2.4 GHz. Two arrays having 49 and 81 MSRR unit cells are then simulated and modeled with the dipole antenna placed above. The results are of great importance as the directivity reaches 6 dB for the configuration of 9 × 9 unit cells. This confirms that the MSRR can perfectly replace the conventional ground plane antenna in order to improve the gain and the directivity of their radiations.

Low Frequency Noise Analysis in Advanced CMOS Devices

A review of recent results concerning the low frequency noise in modern CMOS devices is given. The approaches such as the carrier number and the Hooge mobility fluctuations used for the analysis of the noise sources are illustrated through experimental data obtained on advanced CMOS generations. Furthermore, the impact on the electrical noise of the shrinking of CMOS devices in the deep submicron range is also shown.

Effective permittivity of snow for radar detection: Numerical validation by the fem method

This paper presents a step-by-step procedure to extract the effective permittivity of dry and wet snow in an electromagnetic simulator. The S-parameters are extracted using HFSS (High Frequency Structure Simulator), which is a Finite Element Method (FEM) full wave simulator. The permittivity curve is calculated using the S21 retrieval method. The calculated permittivity is compared with theoretical mixture models (Maxwell Garnett and Bruggeman Symmetric) with a verification that it lies between the effective permittivity theoretical bounds.

Compact low profile antenna based on MSRR-AMC reflector

This paper is dedicated to the study of volumetric MSRR-based AMC structure. The characteristics of a single MSRR unit cell are investigated; and a volumetric miniaturized AMC block is then designed. In order to validate the approach used to simulate an infinite periodic structure, a block of nine aligned layers is then simulated. The next step is to add a printed dipole antenna as an application to validate the performance of the AMC block. The results are very excellent and promising if compared with the simple dipole antenna as an enhancement of 5 dB is achieved considering the directivity. The front to back ratio is found to be about 20 dB.

DC Characterization of Different Advanced MOSFET Architectures

A review of recent results concerning the DC characterization of FD- and Double Gate SOI MOSFET’s and FinFETs in modern CMOS technologies is given. By proper extraction techniques, distinction between the different interaction mechanisms is done. Parameter extraction conducted at room and low temperature clearly indicates that the mobility is directly impacted by shrinking the gate length in sub 100nm architectures.

Development of a 3D scanning system for magnetic near-field characterization

This paper presents a near-field scanning system with the design and calibration of two three dimensional (3D) magnetic field probes. They consist of three orthogonal loops, combined together, the first probe (P1) contains three conventional loops joined in a plastic cube, and the second one (P2) is a PCB probe printed on an FR4 substrate of 3.2 mm thickness. Probe P1 has a total dimension of 10x12x13 mm3 whereas in probe P2 the dimensions are reduced to 9x9x3.2 mm3. The antenna factor of the designed probes was calculated using TEM cell for a frequency range from 10 MHz to 1 GHz. The probes were validated using a standard circuit. Then they are used to characterize the radiated magnetic field from an RFID reader antenna.

Multi-Frequency Approach for Oil Spill Remote Sensing Detection

Lebanon witnessed one of its biggest dangerous environmental crisis due to the oil spill caused by Israel bombard of fuel storage tanks in war 2006. Official reports stated that around 15000 tons of heavy fuel oil spilled in sea water. The spill threatened the maritime and human life and caused severe environmental disasters. On an international scale, the European Space Agency (ESA) stated that more than 4.5 million tons of oil is the estimate of the annual spill worldwide. Therefore, it is really crucial to have an oil spill detection system that is able to specify the spill area and to provide statistical information about the situation. One of the main techniques used nowadays is airborne and satellite remote sensing systems. The European Maritime Safety Agency (EMSA) lunched in 2016 the need to use a complementary system to the present satellite maritime surveillance system. In our work, we propose the use of drones for oil spill detection. In this paper, we present a multi-frequency technique in order to detect thick oil spill in ocean. This technique is also capable of providing an estimation of the oil thickness from reflectivity measurements affected by ocean roughness and noise in electronic devices. Numerical simulations are calculated using High Frequency Electromagnetic Field Simulation (HFSS) validating the theoretical calculations.

Sampled Antenna Array Digital Beamforming for LTE-Advanced

In this paper, a beamforming system for LTE- Advanced based on Array sampling technology is proposed. Antenna Array that has been designed covers LTE mid and high bands. RF multiplexer 8x1 switch has been designed and simulated. The system is composed of agile RF frontend and FPGA digital signal processing unit.

Behavior of different structures to design AMC for Europe LTE bands

This paper is dedicated to study and compare the behaviors of conventional split ring and S-shaped resonators for designing Artificial Magnetic Conductor. S-Shape resonator is proven more technical and proficient considering its geometrical characteristics. The design can be used for communication application in Long Term Evolution bands. Results are obtained by ANSYS HFSS (High Frequency Structure Simulator); a general purpose 3D interface for the design, analysis, and simulation of electromagnetic components.

Practical design for circularly polarized dual off-center aperture-coupled microstrip antenna for GPS application

This paper is dedicated to the design of circularly polarized dual off-center aperture-coupled Microstrip antenna for GPS application. First, the dimensions of the apertures and the square patch antenna are optimized. The global performance is then investigated after integrating a hybrid directional coupler. The return loss is better than 10 dB for a wide-band of 0.28 GHz whereas the realized gain is better than 8 dB. This antenna showed the capability to receive the signals of low altitude satellites.