Chadi Nader

Modelling Resonance Frequencies of a Multi-Turn Spiral for Metamaterial Applications

The planar metal particles, consisting of a multi-turn spirals, are studied with the aim of using them to realize high impedance surfaces or as an elementary cell to create an artiflcial material. These spirals present a resonant behaviour in a certain frequency band. To obtain miniature devices, a compromise between the surface and the e-ciency of the resonance must be found. The compactness of the particles can be increased by using s spirals. However, the accuracy on resonant frequency of existing models is not su-cient for our applications. We present a simple analytical model that determines the resonant frequency from the geometric dimensions of the approximated model. This model is verifled by electromagnetic simulations and by measurements.

COPLANAR METAMATERIAL MICRO-RESONATOR

We propose a metamaterial coplanar stop-band fllter made of multi-turn rectangular spiral particles. Numerical and experimental results show the feasibility of devices with dimensions more than 10 times smaller than those in the literature and with good performances.

U-Patch Antenna for RFID and Wireless Applications

in this paper, we propose a new multi-band patch antenna structure for embedded RFID (Radio Frequency Identification) readers and wireless communications. The proposed antenna is a dual band microstrip patch antenna using U-slot geometry. The operating frequencies of the proposed antenna are chosen as 2.4 and 0.9 (GHz), obtained by optimizing the physical dimensions of the U-slot. Several parameters have been investigated using Ansoft Designer software. The antenna is fed through a quarter wavelength transformer for impedance matching. An additional layer of alumina is added above the surface of the conductors to increase the performance of the antenna.

Microstrip Bandpass Sensor Based on Distributed Capacitors

A microstrip bandpass filter with rectangular patch coupled resonator is presented. The filter is designed to be more affected by the dielectric layer above the conductors compared to the same type of parallel-coupled bandpass filter. The filter is designed to operate between 1 GHz to 3 GHz and this can be a sensor base on distributed capacitors. The agreement between the circuit simulator and measured results is excellent and gives a very good prediction for the filter characteristics. The aim of this prototype filter is to show insertion loss (IL) at the bandpass transmission response when a dielectric material is above or near the conductors. A large study around the sensibility and the effect of the dielectric layer is done in order to evaluate its performance in detection and dielectric characterization.