On the coupling integrals arising in the method of moments formulation of laterally bounded structures

A generic integral equation and method of moments formulation is presented for laterally bounded stratified media including planar metallization. The main asset of the developed approach is its flexibility, as it encompasses generic lateral boundary conditions and explicitly applies to any linear subsectional basis functions with constant surface divergence. This includes the rooftop functions on rectangular and triangular supports currently proposed in standard method of moment meshers. This approach provides closed expressions for the coupling integrals appearing in the method of moments matrix elements. These formulas are based of Green's functions modal expansions and in the possibility, conclusively demonstrated in this paper to transform the surface integrals into contour integrals allowing an efficient and systematic implementation of the procedure. Full derivations are presented for several lateral boundary conditions, including rectangular and circular metallic cavities and periodic structures. Numerical examples including the analysis of real-life planar boxed circuits are presented. In all cases the obtained results compare favourably with other existing techniques

3D-Spiral small antenna design and realization for biomedical telemetry in the MICS band

This work presents the design and realization procedure of small implantable antenna for biotelemetry applications. The radiator occupies a volume smaller than 3 cm(3) (without its biocompatible insulation), is well matched within the Medical Implanted Communications System band and shows an adequate gain (-28.5 dB) while introduced in the appropriate equivalent body medium. The latter is a homogeneous phantom with muscle dielectric properties. A prototype has been manufactured and measurements agree with theoretical predictions. Particular attention is paid to the building requirements such as the presence of glue. Specific Absorption Rate (SAR) distribution has been computed evaluating the maximum power deliverable to the antenna in order to respect the regulated SAR limitation

Enhanced backscattering by multiple nanocylinders illuminated by TE plane wave

In this paper, we study the multiple scattering by electrically small (the radius of the cylinder is much smaller than the wavelength) plasmonic nanocylinders near surface plasmon resonance. The cylinders are assumed to be identical in dimension and composition. The incident plane wave is assumed to be TE polarized so that the plasmon resonance of two-dimensional cylindrical structures (for both individual and group of cylinders) can be excited. It is found that multiple plasmonic cylinders enhance the near-field magnetic field intensity due to mutual coupling. When the electrical dimension q of the cylinders (q=k(0)R, where k(0) is the wave number of the free space and R is the radius of the cylinder) is fixed, the magnitude of the field distribution primarily depends on the positions of the cylinders at normal incidence. (C) 2008 American Institute of Physics. [DOI: 10.1063/1.2975214

Effect of realistic modeling of deep brain stimulation on the prediction of volume of activated tissue

Deep brain stimulation (DBS) is a well-established treatment for Parkinson's disease, essential tremor and dystonia. It has also been successfully applied to treat various other neurological and psychiatric conditions including depression and obsessive-compulsive disorder. Numerous computational models, mostly based on the Finite Element Method (FEM) approach have been suggested to investigate the biophysical mechanisms of electromagnetic wave-tissue interaction during DBS. These models, although emphasizing the importance of various electrical and geometrical parameters, mostly have used simplified geometries over a tightly restricted tissue volume in the case of monopolar stimulation. In the present work we show that topological arrangements and geometrical properties of the model have a significant effect on the distribution of voltages in the concerned tissues. The results support reconsidering the current approach for modeling monopolar DBS which uses a restricted cubic area extended a few centimeters around the active electrode to predict the volume of activated tissue. We propose a new technique called multi-resolution FEM modeling, which may improve the accuracy of the prediction of volume of activated tissue and yet be computationally tractable on personal computers