Aleksandra J. Krneta

Modeling of human bodies for analysis of wireless body area networks in crowds

We present an approach for modeling of human bodies in crowds for the analysis of channel parameters in wireless body area networks. The approach uses distributed surface impedances with method of moments based on surface integral-equation formulation. It significantly reduced the computer resources needed for the electromagnetic analysis, and keeps the final results accurate in a statistical sense.

Evaluation of Potential and Impedance Integrals in Analysis of Axially Symmetric Metallic Structures to Prescribed Accuracy Up To Machine Precision

This paper presents a novel method for evaluating potential and impedance integrals appearing in the method of moment analysis of arbitrary axially symmetric metallic structures based on exact wire kernel and higher order bases. Due to new variable transforms proposed for singularity cancellation and smoothing the integrands, high accuracy up to machine precision is achieved using relatively small number of integration points. Simple formulas are determined for predicting a number of integration points needed for prescribed accuracy. Benefits of high-precision evaluation of impedance integrals are illustrated on a number of numerical examples.

Method for improving convergence of the reflected Sommerfeld integrals for a multilayered media

Reflected Sommerfeld integrals over a half-space or over a multilayered media are semi-infinite and for small heights of source and field points tend to converge slow. For improving the convergence, slowly converging terms can be asymptotically extracted, and analytically integrated. In this paper, by the use of one of the analytically solvable Bessel function integrals, a new integrand term is extracted. The results is that the convergence is improved and the numerical effort (and, thus, the computational time) reduced by the factor of ten.

Modeling of EM wave propagation in the vicinity of the human body by the use of WIPL-D software

By the means of numerical simulations using WIPL-D Pro software, some aspects of electromagnetic (EM) waves propagation in the close proximity of the human body were studied. Human torso was modeled by a homogeneous dielectric ellipsoid of appropriate electrical parameters. Transfer function between the two antennas on the body as function of their mutual distance, and intensity and polarization of the near field of one antenna on the human body were observed. Frequencies 2.45 GHz and 850 MHz, as two characteristic WBAN frequencies were chosen for the analysis. It was confirmed that on both frequencies transfer function decays approximately exponentionaly with the distance. It was determined that the polarization of the electric field of the antenna on the body significantly varies with the position. It was illustrated that the communication between antennas are established by both direct and surface (diffracted) component of the EM wave.

Matrix fill in analysis of axially symmetric antennas using very high expansion orders

The new implementation of max-ortho bases in a method for analysis of axially symmetric antennas is examined from the aspect of analysis-time requirements and average number of integration points per system matrix element. Results for a thick dipole antenna show that for the same number of unknowns, expansion orders up to 64 require fewer resources than lower order bases (i.e. 1st and 2nd order).

Analytic solutions of electromagnetic fields in inhomogeneous media

We present guidelines for teaching students how to analytically solve problems that involve inhomogeneous media in electrostatic fields, stationary current fields, and stationary magnetic fields. At the introductory level, the focus is on recognizing classes of problems that can be solved in closed form and applying simple rules, based on comparison with solutions in homogeneous media. At the intermediate level, the focus is on strict proofs based on vector calculus.

Comparison of five antennas for WBAN applications

In this paper five antennas for Wireless Body Area Networks (WBAN) will be analyzed in detail. By the use of WIPL-D Pro software, reflection losses, radiation patterns and efficiency of these antennas in free space, close to a model of an arm and of a human body were analyzed. The antennas are mutually compared with respect to the maximal and minimal gain and efficiency.