Nathalie Raveu

Improvement in the wave concept iterative procedure through spectral connection.

An improvement of the wave concept iterative procedure (WCIP) is implemented for bulky devices without involving excessive computational storage and simulation times. The description of such features has been a major difficulty since both small and large dimensions exist which led to hardened constraints when accuracy is required. An alternative consists in the use of appropriate modifications and interfaces of coarse numerical meshes (Macropixel) which allow implementation of fine feature within circuit area. These concepts were validated through comparison between measurement and simulated results performed by classical and improved WCIP method, for patch antennas.

Scale Changing Technique for MEMS-controlled phase-shifters

The original scale changing technique is applied to the electromagnetic modeling of MEMS-controlled phase-shifters used in reconfigurable reflectarrays. The phase shift is derived from the simple cascade of networks, each network describing the electromagnetic coupling between two scale levels. This technique allows computing quasi-instantaneously the 1024 phase-shifts achieved by 10 RF-MEMS switches distributed on the surface of the phase-shifter. Moreover sensitivity as regards of RF-MEMS switches losses was discussed. Experimental data are given for validation purposes

Electromagnetic modeling of planar almost periodic structures

After the presentation of almost periodic structures and their interest in circuits, antennas and diffraction, one focus the study on bidimensional structures which have periodic cells but non periodical patterns inside the cells. The bi-dimensional leaky waves antennas array with a central feed and the circuit in package made up with metallic via in an arbitrary arrangement are particular cases of almost-periodic structures. Two numerical methods are used for modeling the almost periodic planar structures: the method of moments and the wave concept iterative procedure.

Scale changing technique design and optimisation tool for active reflect-arrays cell

This study deals with the design and optimisation of an active phase-shifter cell for MEMS-based reflect-arrays. Technological implementation was investigated in order to enhance the cell performances. The sensitivity of these performances to MEMS capacitance ratio as well as MEMS failure were studied. Those studies were performed using the scale changing technique (SCT). Lastly, extra performance improvement was investigated using genetic algorithm and DOE- based optimisation techniques.

Sinrd Circuits Analysis with Wcip

This article presents the Wave Concept Iterative Procedure (WCIP), an efficient method for characterization of substrate integrated Non-Radiative Dielectric (SINRD) passive circuits based on wave concept formulation and its iterative solution. WCIP simulations are compared to measurements and Finite Element Method simulations. A good agreement is achieved with computation time saving.

CALCULATION OF THE MUTUAL COUPLING PARAMETERS AND THEIR EFFECTS IN 1-D PLANAR ALMOST PERIODIC STRUCTURES

This paper proposes a new modal analysis based on Floquets theorem which is needful for the study of a 1-D periodic phased array antenna excited by arbitrary located sources. This analysis requires an accurate estimation for calculation of the mutual coupling parameters (for example: mutual impedances or admittances ...) between the array elements and their efiects integrating a large planar radiating structure. Two difierent formulations are suggested, in spectral and spatial domains, to solve the problem and to calculate the coupling coe-cients between the neighbouring elements in a periodic environment. Important gain in the running time and used memory is obtained using Floquet analysis. One numerical method is used for modeling the proposed structures: the moment method combined with Generalized Equivalent Circuit (MoM-GEC).

Modeling of infinite passive planar structures using scale-changing technique

Scale-changing technique has been successfully used for the modeling of a passive infinite reflectarray. The obtained results are successfully validated using HFSS simulation results. This technique has proven to be more time-efficient as compared to the conventional full-wave techniques especially for the geometries where greater number of scales can be defined e.g. in case of frequency selective surfaces or structures which utilize active MEMS. The scale-changing technique is intended to be used for the finite array problems in the near future to model the mutual coupling between the cells.

Multi-scale approach for the electromagnetic modelling of MEMS-controlled reflectarrays

A new approach, named the scale changing technique, is performed here for the electromagnetic modelling of reflect arrays controlled by radio-frequency micro- electromechanical switches. Based on the partition of the reflectarray surface in planar sub-domains with various scale levels, this technique derives the phase- shift dynamics from the simple cascade of networks, each network describing the electromagnetic coupling between two scale levels. Higher-order modes allow the accurate representation of the electromagnetic field local variation while lower-order modes are used for coupling the various scales.

WCIP APPLIED TO SUBSTRATE INTEGRATED WAVEGUIDE

This article presents an e-cient method for characteriza- tion of substrate integrated passive circuits. The analysis is based on the wave concept formulation and the iterative resolution of a system of two equations between incident and re∞ected waves. Simulations ob- tained are compared with analytical references and HFSS simulations. A good agreement is achieved with computation time saving.

Wcip Applied to Active Plasma Circuits

The Wave Concept Iterative Procedure is validated for multi-layered substrate with frequency dependent and negative index media. By shifting the plasma frequency, reconflgurable fllter design is proposed with a center frequency tunability of 25%. Sensitivity to collisional plasma is proposed.