Hassen Zairi

Analysis of a new annular multi-slits antenna using wave concept iterative process in cylindrical coordinates

In this paper, a new antenna for satellite applications is proposed. This antenna is designed to operate at any frequency desired. It consists of a circular microstrip patch antenna which incorporates concentric annular slits, and it is printed on a grounded substrate. The details of the proposed antenna design and numerical results are presented and discussed. The wave concept iterative procedure in cylindrical coordinates is used to analyze this new antenna. Using the proposed procedure, less computing time and memory are needed to calculate the electromagnetic parameters of the annular multi-slits antenna.

A new wave concept iterative method in cylindrical coordinates for modeling of circular planar circuits

The purpose of this paper is the formulation of a Wave Concept Iterative Process (WCIP) for the analysis of the microwave planar circuits printed between two dielectric mediums in a cylindrical metallic box. This method is based on the transverse wave formulation. It also uses the Hankel Transform to express the integral relation in a spectral domain. An example of annular ring and circular patch loaded by annular ring has been studied and the obtained results validate the new approach. The good agreement between the simulation results and the experimental published data justifies the design procedure and validates the present analysis approach.

Modelling of two-dimensional periodic arrays using iterative method

The paper presents an implementation of an iterative method, based on the wave concept, for numerical modelling of radiating stratified periodic structures composed of metallic patches deposited on a dielectric layer. This method includes a two dimensional fast Fourier transformation (FFT-2D) in a periodic wave guide environment. The studied technique is applied to characterize a periodic FSS structure. A comparison of simulation results with the available literature allows the validation of the iterative approach.

Low loss substrate integrated waveguide slot antenna

Recently, substrate integrated waveguides are the best choice for micro-wave and millimeter-wave applications thanks to their integrability and good performance, what made them a good alternative for rectangular and planar waveguides. The SIW structure suffers from three kinds of losses, radiation losses, dielectric loss and conductor loss. The SIW vias risk a radiation loss due to the space between them. Dielectric loss is due to the loss tangent of the material of the substrate, Ohmic loss is caused by the conductivity of the metallic plans and vias. This paper presents an optimization on an SIW slot antenna structure to minimize losses. This optimization provided a better Quality factor, better gain and decreased losses.

Design and development of circular filter using QSIW resonator

In this paper, we present a new Quarter-Mode Substrate Integrated Waveguide filter (QMSIW). A prototype of the proposed filter operating at 8.88 GHz was simulated under CST Microwave Studio and HFSS software. Return losses represent better than 20dB, while the simulated insertion losses represent 0.4dB. The simulated results of this filter show good agreement, with a size reduction of about 75 and 50 percent compared to the SIW and HMSIW filters, respectively. The proposed QMSIW filter has a wide bandwidth, low losses and a compact size, the total size being less than 12 mm × 6.7 mm × 0.508 mm without the feed lines.

Concentric annular slot antenna

This paper focuses primarily on improving the gain of the circular microstrip patch antenna thanks to the presence of two concentric annular slots. The proposed antenna is excited by a coaxial probe and the design was aided by simulation through using CST resonance antenna at 4.38GHz with gain of 10.2dB and 12.1dB without and with slot respectively. This band covers the band of Radar applications.

A compact bandpass substrate integrated waveguide filter

The present paper highlights a compact and low cost bandpass substrate integrated waveguide (SIW) filter with two cavities. The (SIW) filter has well-known advantages of low insertion loss and high selectivity. It provides a significant solution to the integration of planar and nonplanar circuits. As the simulated results show, the stopband rejection of filter is more than 30dB while the insertion loss is less than -0.8dB at the bandpass, thus due to the effects of the high Q resonators.

A new iterative method for analysing nonlinear photonic-crystal structures

The article presents an efficient iterative method for analysing non-linear photonic crystals. The new approach is used for analysing a frequency converter constructed with a 2D pillar-type photonic crystal waveguide structure. The considered converter uses the non-linear properties and the compound waveguide structure. The analysis is based on the iterative resolution of two relationships between incident and reflected volume-waves. The reflection operator is expressed using Hankel functions. Numerical results have been obtained with moderate CPU time and memory requirement. Simulations obtained are in agreement with recent published results.