Shermila Mostarshedi

Stochastic Analysis of Scattered Field by Building Facades Using Polynomial Chaos

This paper presents a statistical assessment of scattered field from a building facade having random physical and geometrical parameters. A simple inhomogeneous model is considered for the building, and the calculation method is based on Greens functions. The basis of polynomial chaos expansion method is explained and applied to estimate the scattered electric field from a building facade having 8 random parameters, in specular and nonspecular scenarios. Uncertainty analysis and total output distribution are discussed in different diffraction zones of the building.

A Multilayered Coil Antenna for Ingestible Capsule: Near-Field Magnetic Induction Link

A compact multilayered stacked ingestible coil antenna is investigated for medical systems. The inductive link, comprising a 5-layer transmitter coil antenna and a 3-turn receiver spiral coil, is modeled through a tissue-simulating liquid modeling the human body. The diameter and the thickness of the transmitter coil are respectively equal to 1 cm and 5 mm, while the dimensions of the receiver coil are equal to 7 × 8 cm2. The variations of the position and the orientation of the capsule antenna are taken into account to evaluate the coupling response between the two magnetically coupled coils. We found that the inductive link presents an attractive option for improving the lifetime of ingestible capsules.

Near- and Far-Field Models for Scattering Analysis of Buildings in Wireless Communications

This paper presents an efficient building modeling for urban propagation prediction. By dividing the whole computation area into near and far zones, two different models are adopted for buildings. As demonstrated for a building facade, a precise description of the heterogeneities is necessary for an observation point situated in the building near field, whereas in the far-field area, a good accuracy is maintained by homogenizing the facade electric properties. Therefore, in the far area, a homogenized reflection coefficient is taken for each facade, and a radar cross section (RCS) is calculated for one or a set of far buildings, taking the multiple reflections into account. In a near area, the simulator can apply the classical ray-tracing code using the detailed facade description while taking account of far building groups through their RCS. The distance of homogenization and RCS validity is obtained using a reference method based on Greens functions.

Calculation of Reflected EM Fields by Mixed Plane Dielectric Media Using Green's Functions for Applications in Urban Environment

Greens functions for semi-infinite media are derived and used to calculate the reflected electromagnetic fields by plane composite dielectric surfaces. The method is not demanding in terms of computer resources and calculation time; it is thus applied to exterior building facades in urban environments. The method takes into account the architectural details which are usually neglected in ray-tracing algorithms.

Statistical analysis of scattered field by building facades

This paper presents a statistical assessment of scattered field from a building facade presenting random physical and geometrical parameters. A simple 2D inhomogeneous model is considered for the building and the calculation method is based on Greens functions. Polynomial chaos expansion is used for uncertainty analysis and different statistical results are presented.

Increasing contribution of stochastic methods in the characterization of complex systems: Reverberation chamber and urban environment

The use of stochastic approaches for the electromagnetic characterization of complex systems is illustrated in two cases that are reverberation chambers and urban environment. Several stochastic approaches are adopted in both cases, from a perturbative approach to the determination of distributions; the indications they provide as well as the associated requirements in terms of computation time or measurement complexity differ.

Statistical analysis of the influence of the morphology onto the whole-body exposure to radio-frequency waves

The increasing use of wireless technologies and the multiplicity of the usages arouse a lot of questions from the general public about possible health effects of these technologies. The influence of the human variability, in particular the morphology, onto the exposure induced by electromagnetic fields is one of the important topics. The development of high performance computing allows one to use nowadays the numerical dosimetry to assess the specific absorption rate (SAR) on which the associated uncertainty is a key question. But despite the large efforts that have been carried out over the last 20 years to develop computational methods as the FDTD, the evaluation of the SAR remains a time consuming procedure. Consequently, the uncertainty quantification in dosimetry is a true challenge and the propagation of the variability of the input morphological parameters through the physical model of the FDTD cannot be addressed with classical methods such as the Monte Carlo simulations. Advanced surrogate modeling techniques such as the polynomial chaos expansion (G. Blatman and B. Sudret, Journal of Computational Physics, 230(6), 2011, pp. 2345–2367) have to be used.

Advanced human RF exposure assessment using FDTD and polynomial chaos expansion

Nowadays new wireless communications systems that are using Radio Frequency (RF) Electromagnetic Fields (EMF), such as smart phones, tablets, laptops are intensively used with versatile usages. Despite the existing protection limits and this increasing usage of wireless systems, there is a public concern about possible health impacts of the RF EMF exposure.

Near ground wave propagation modeling for wireless network applications

As many applications with antennas placed near an interface are getting developed, it becomes necessary to take properly into account the impact of this interface in the wave propagation. In this article, it is shown that the classical ray-tracing approach may lead to inaccurate results, so a rigorous modeling must be envisaged. The Greens functions of this problem, written as Sommerfeld integrals, offer the possibility to deduce important guidelines which help to better understand and handle this kind of propagation.

Statistical analysis of scattered field by building facades using polynomial chaos expansion

This paper presents a statistical assessment of scattered field from a building facade presenting random physical and geometrical parameters. A simple 2D inhomogeneous model is considered for the building and the calculation method is based on Greens functions. Polynomial chaos expansion is used for uncertainty analysis and different statistical results are presented.