M.F. Wong

Electromagnetic propagation into reinforced-concrete walls

A 3D finite element method with decomposition on Floquets modes is presented to study the transmission parameters of building walls. The influences of gratings in concrete walls, of wall dimensions, and of the electromagnetic excitation with single field of a plane wave or with diffuse field, on wall transmission properties are then studied by this method.

A new global time-domain electromagnetic simulator of microwave circuits including lumped elements based on finite-element method

This paper proposes an extension of the Finite Element Time Domain (FETD) method for the global electromagnetic (EM) analysis of complex inhomogeneous microwave distributed circuits, containing linear or non linear lumped elements. This technique combines Maxwells equations and circuit equations, using directly SPICE software. Results are given for a capacitor, a resistor as well as a Schottky diode.

Statistical analysis of whole-body absorption depending on anatomical human characteristics at a frequency of 2.1 GHz

In this paper, we propose identification of the morphological factors that may impact the whole-body averaged specific absorption rate (WBSAR). This study is conducted for the case of exposure to a front plane wave at a 2100 MHz frequency carrier. This study is based on the development of different regression models for estimating the WBSAR as a function of morphological factors. For this purpose, a database of 12 anatomical human models (phantoms) has been considered. Also, 18 supplementary phantoms obtained using the morphing technique were generated to build the required relation. This paper presents three models based on external morphological factors such as the body surface area, the body mass index or the body mass. These models show good results in estimating the WBSAR (<10%) for families obtained by the morphing technique, but these are still less accurate (30%) when applied to different original phantoms. This study stresses the importance of the internal morphological factors such as muscle and fat proportions in characterization of the WBSAR. The regression models are then improved using internal morphological factors with an estimation error of approximately 10% on the WBSAR. Finally, this study is suitable for establishing the statistical distribution of the WBSAR for a given population characterized by its morphology.

A new global finite element analysis of microwave circuits including lumped elements

A new fullwave global analysis of complex inhomogeneous structures including passive or active, linear or non linear lumped elements is presented. Only one electromagnetic simulation of the distributed part, by a 3D finite element method using edge elements, is needed corresponding to the insertion of several lumped elements placed at the same position. Results for a resistor, a diode inserted in a microstrip circuit as well as a Gunn diode amplifier are presented and comparisons with measurements are given for an active structure.

Diakoptics using finite element analysis

A diakoptics technique based on the use of finite element method is developed in this paper. This method enables the analysis of large microwave structures by computation of subdomains. The algorithm is validated on a test case of a step in width finline discontinuity.

An hybrid formulation combining FDTD and TDPO

The finite difference time domain (FDTD) technique has been proven to be particularly well suited to study microwave circuits and antennas. However, its main limitation results from the increase in both computation time and memory storage when the studied structures become larger. On the other hand, asymptotic approaches, such as the physical optics are generally used to account for very large scatterers but are not valid to study small radiating structures. Several examples have been reported, in which a rigorous electromagnetic method was combined with an asymptotic approach in order to study small radiating sources close to large scatterers. So-called hybrid methods have been demonstrated as able to account for the environment of the antenna while maintaining the needed accuracy in the description of the antenna itself. This paper proposes a new hybrid technique that combines FDTD with the time domain physical optics (TPDO). As the whole approach is performed in the time domain, it is expected to be suitable for broadband analysis. Moreover, the physical optics allows the closeness between the small element and the large scatterer contrary to geometrical optics where the source is supposed to be far from the obstacle. Their support may even be the same but edge diffraction phenomena are not modeled.

Variability on the Propagation of a Plane Wave Using Stochastic Collocation Methods in a Bio Electromagnetic Application

In this letter, the uncertainties on the angles of propagation of a plane wave in a bio electromagnetic application are studied using two non intrusive stochastic collocation methods. The proposed techniques are used in this application, which employs a finite-difference time-domain scheme, but they can be used when applying other kinds of methods without modifying programs. The results obtained using the two approaches are compared. The stochastic collocation methods are used to determine the influence of the uncertainty on the angle of propagation of a plane wave on the obtained specific absorption rate. Global sensitivity is analyzed.

A new global time domain electromagnetic simulator of microwave circuits including lumped elements based on finite element method

This paper proposes an extension of the Finite Element Time Domain (FETD) method for the global electromagnetic (EM) analysis of complex inhomogeneous microwave distributed circuits, containing linear or non linear lumped elements. This technique combines Maxwells equations and circuit equations, using directly SPICE software. Results are given for a capacitor, a resistor as well as a Schottky diode.

Rigorous evaluation of specific absorption rate (SAR) induced in a multilayer biological structure

This paper compares the specific absorption rate (SAR) values induced in human tissues once obtained when using the equivalent liquid dielectric properties of the equivalent liquid filling the phantom used in SAR measurements and from a model that proposes realistic continuation of tissues in the human body. The calculations are performed for the case of a dipole close to a multilayer structure representing the different body tissues using integral equations techniques solved by the method of moments

Inverse source characterization for electromagnetic near field reconstruction and interaction with the environment

Antennas are sources of electromagnetic radiation. The radiation pattern and gain can be routinely obtained by measurements and characterize efficiently the radiation of the source regardless of its actual complexity. However in some applications, one may need to analyze the source interaction with its close environment in the near field region instead of the far field one. In this paper, we partition the antenna geometry with overlapping smaller spheres than the minimum one. The field at a point in the near field is the superposition of the field radiated by the sub-sources or equivalent sources circumscribed by the small spheres. The inverse or synthesis problem is to find these equivalent sources given the radiation pattern or its spherical harmonics spectrum. The radiated fields of the equivalent sources are expanded in terms of spherical harmonics which is locally associated with their minimum spheres