Fadi Khalil

Multi-Scale Approach for the Electromagnetic Simulation of Finite Size and Thick Frequency Selective Surfaces

The scattering analysis from metallic Grid FSS consisting of rectangular perforations on a thick metallic screen illuminated by an oblique incident plane wave is presented. The grid structure is analyzed using Scale Changing Technique (SCT) which is based on the partition of the grid-plane into planar sub-domains deflned at various scale-levels. Electromagnetic interaction between subsequent scales is modeled by mutually independent Scale-Changing Networks and flnally the complete structure is simply represented by a cascade of these networks. Very good agreement is obtained between simulation results from SCT and the Finite Element Method (FEM) when computing the re∞ection/transmission coe-cients and electromagnetic fleld backscattered by thick and flnite size frequency selective surfaces. The computation time is signiflcantly reduced when using SCT-based software compared with the FEM simulation tool. The accurate prediction of the electromagnetic scattering by flnite size arrays is of great practical interest in the design and optimization of modern frequency selective surfaces (FSSs), re∞ect-arrays and transmit-arrays. A complete full-wave analysis of these structures requires generally enormous computational resources due to their large electrical dimensions which would require prohibitively large number of unknowns to be solved. The unavailability of e-cient and accurate design tools for these applications limits the engineers with the choice of low performance simplistic designs that do

Electromagnetic simulation of MEMS-controlled reflectarrays based on SCT in grid environment

The SCT-based simulation tool consists of a MATLAB code developed to run on a single machine in order to predict the phase-shift for all possible MEMS configurations. The 1024 configurations of a phase-shifter cell are obtained by the UP/DOWN positions of the 10 RF MEMS switches inserted in the slit of the 3 metallic patches (Legay, 2005). This problem represent a very computational demanding task on stand alone machines. In this work we report how parallel distributed computing in grid environment offers a very suitable tool for this specific problem. The multi-port networks are computed on GRID5000 nodes and it has yielded a 90.5% of simulation time reduction while keeping the same accuracy for the several frequency values we have tested.

Simulation of micro electro-mechanical systems (MEMS) on Grid

Complex optimization problems are of high interest for Process Systems Engineering. The selection of the relevant technique for the treatment of a given problem has already been studied for batch plant design issues. Classically, most works reported in the dedicated literature yet considered item sizes as continuous variables. In a view of realism, a similar approach is proposed in this paper, with discrete variables for representing equipment capacities, which leads to a combinatorial problem. For this purpose, a Genetic Algorithm was used, which is multiparametric by nature and a grid approach is perfectly relevant to this case study, since the GA code must be run several times, with different values of some input parameters, to guarantee its stochastic nature. This paper is devoted to the presentation of a grid-oriented GA methodology. Some significant results are highlighted and discussed.In the present paper, the methodology of interoperability between ITBL and Grid-TLSE is described. Grid-TLSE is an expert web site to provides user assistance in choosing the right solver for its problems and appropriate values for the control parameters of the selected solve. The time to solution of linear equation solver strongly depends on the type of problem, the selected algorithm, its implementation and the target computer architecture. Grid-TLSE uses the Diet middleware to distribute computing tasks over the Grid. Therefore, extending the variety of computer architecture by Grid middleware interoperability between Diet and ITBL has a beneficial impact to the expert system. To show the feasibility of the methodology, job transfering program as a special service of Diet was developed.

Grid- Based Global Electromagnetic Simulation Tool for Parametric Distributed Analysis of Array Antennas

Full-wave electromagnetic solver based on the Transmis- sion Line Matrix Method has been deployed on Grid test-bed. This Grid-based electromagnetic approach exploits the availability of com- puting node at disposal through the Grid to face the demand of ar- bitrary large simulations by allocating a corresponding amount of re- sources hence minimizing the overall elapse time. In order to highlight the beneflts of using computing Grids in electromagnetic simulations, a parametric study of planar re∞ectarray antennas based on microstrip technology has been carried out. The e-ciency of distributed comput- ing when a very large number of computation units (nodes) are involved in the computation of large and non-uniform re∞ectarray antennas is reported.