Serge Toutain

Fast numerical method for electromagnetic scattering by rough layered interfaces: propagation-inside-layer expansion method.

Electromagnetic scattering from a stack of two one-dimensional rough surfaces separating homogeneous media is modeled with a rigorous integral formulation solved by the method of moments. We present an efficient numerical method for computing the field scattered by such rough layers, in reflection as well as in transmission. We call this method propagation-inside-layer expansion (PILE) due to its straightforward physical interpretation. To our knowledge, it is the first method able to handle problems for this configuration with a huge number of unknowns. We study the convergence of this method versus a coupling condition and validate it by comparison with results from the literature.

Theoretical investigation of a circular patch antenna in the presence of a left-handed medium

The influence of a left-handed medium (LHM) on the performances of a circular patch antenna is quantified numerically. For this, a homogenization procedure of the LHM is carried out in order to design the patch antenna at a suitable frequency where the losses of the LHM are low. From the first results obtained, it is noted that in the presence of the LHM, the antenna is more directive and has a higher gain.

Integration of pass-band filters in patch antennas.

In this paper, we present the possibility to insert pass-band filters directly in a patch antenna in order to reduce the size of microwave front ends and to master the bandwidth of the antenna. In a first step, commercial filters are used and mounted on the antenna. Then, we propose to develop miniaturized integrated filters which can be directly integrated into the patch antenna.

Integration of a filtering function in an electromagnetic horn

This paper deals with a new concept of filtering antenna. We set up a methodology for designing a filtering antenna based on electromagnetism - circuit joint simulation. We start from a E plane filter which we set up in a electromagnetic horn. We show that is still possible to keep control of both the filtering pattern and the radiating pattern.

Study of a leaky waveguide for the design of filtering antennas

In this paper, we present the possibility to use a leaky waveguide as a radiating structure and to create cavities into this waveguide in order to master the bandwidth of the global structure. We present here the concept of a filtering antenna and the first results about the insertion of resonators into a microstrip line that supports the first higher-order mode of propagation, and about the characterization of the radiation of this mode.

Miniaturized patch antenna for dual-frequency operation

In this paper, we present the design of a miniaturized dual frequency patch antenna. This design is based on the possibility to insert a low pass filtering structure in the basic resonator and on the effect of this structure on the fundamental resonance frequency of the patch. The reduction and filtering techniques combined allow a reduction of size of 70% with dual frequency such as 900 MHz/2 GHz. A good efficiency can be obtained at the two frequencies by choosing correctly the dimensions of the patch and the nature of the substrate.

Numerical simulations of scattering from multilayers separated by one-dimensional rough interfaces

The problem of electromagnetic wave scattering by a stack of two-dimensional Gaussian rough interfaces is solved. The scattered field is expressed from the Kirchhoff approximation where the multiple scattering phenomenon is neglected and the average field (bistatic scattering coefficient) is computed from a Monte Carlo method. The advantage of this method is that it is fast unlike the exact numerical methods as method of moments. The two rough interfaces separate three lossless and homogeneous media. The bistatic scattered field and the scattering cross section are derived in this paper for vertical and horizontal polarizations. The application of this work is the study of electromagnetic modeling of oil slicks on ocean surfaces.

Comparison of efficiency measurement methods for small antennas

The National Center for Scientific Research (CNRS) in France launched a number of specific actions (SA) in order to identify the most challenging issues to be investigated by the French research community. One of these specific actions is dedicated to antenna miniaturisation. The aim of this action is to provide a state of the art and new direction of studies in the following topics: antenna miniaturisation techniques and designs, evaluation of small antenna Q and fundamental limitation in miniaturisations, software issues: computing and benchmark, comparison of different small antennas efficiency measurement methods. This last part gathers three French university laboratories (IETR, IREENA, LEAT) and two French companies (CEA-LETI, SAGEM). Recently, three companies (TCL&ALCATEL Mobile Phones, Bluetest AB, IMST GmbH) and the Chalmers University of Technology have been interested to participate to the efficiency round robin measurements. This paper presents the work already done from January to December 2004.

Electromagnetic theory, CAD and experimental approach, bases of an efficient education in microwave and RF techniques

This paper suggests some teaching approach and gives examples to make more efficient education in microwave and RF techniques and increase the interest of students in such courses.

Use of multimode resonator for the antenna-filter multifunction design

We have presented the design of the antenna filter multi-function using a methodology based on a direct synthesis of the filtering functions and taking into account the electromagnetic constraints. We have showed that we could design either the radiant filter function or the filtering antenna function. From these results we have designed a structure with multi-mode cavities in order to make the filtering function the most compact as possible. We hope to present for the conference some multi-mode radiating filters measurements.