Showing papers by "Concettina Buccella published in 2007"

Prediction of Temperature Increase in Human Eyes Due to RF Sources

Abstract: A numerical study is proposed to investigate the effects of different RF sources on the specific absorption rate (SAR) and maximum temperature increase in the human eye at different frequencies. In particular, a new model of the human head is presented and compared with an anatomical model of the visible human. The high resolution (0.5 mm) of the proposed model allows to consider more eye tissues than previous studies distinguishing the sclera from the retina and choroid. New values of blood perfusion and metabolic rate of these tissues are derived. A plane-wave field is considered as far-field exposure, while realistic models of mobile phone and dipole antennas are used as primary sources for near-field exposure. The obtained results show that the distributions of the SAR and temperature increase depend on the frequency, position, and kind of sources. Finally, attention is paid to the maximum temperature increase in the lens for the SAR values prescribed by the Commission on Non-Ionizing Radiation Protection. To this aim, a scaling approach is proposed, and significant values of temperature increase are found (about C for general public exposure and about 1.5 degC for occupational exposure) for the most critical cases of near-field exposures.

Numerical Prediction of SAR and Thermal Elevation in a 0.25-mm 3-D Model of the Human Eye Exposed to Handheld Transmitters

Abstract: A 3D numerical study is proposed to compute the specific absorption rate (SAR) and maximum temperature increase in the human eye exposed to RF fields generated by handheld transmitters. A very accurate model of the human eye is proposed using a very fine discretization with 0.25 mm cubic cells that permits to consider many eye tissues in the calculations. The numerical aspects of the bioheat equation solution in the human head are discussed. The temperature increase in the exposed human eye is predicted for widely used handheld transmitters, such as walkie-talkies, mobile phones and WiFi- based devices.

Penetration of Ultra-wideband (UWB) Communication Signals Through Walls

Abstract: Ultra-wideband (UWB) radio propagation is investigated to evaluate the signal attenuation due to walls of common materials widely used in indoor environment as glass, wood and dry wall This study is carried out by experimental and analytical techniques Time domain measurements of the shielding effect produced by panels of dispersive materials are presented The experimental set-up for UWB applications is also described A procedure based on the transmission line (TL) theory applied to shielding problems is developed to calculate the field attenuation in frequency domain and the transient results are then obtained by the Inverse Fast Fourier Transform (IFFT) The analytical and the experimental results are finally compared

Simulation of an Indoor Power Cable Network for PLC Applications

Abstract: A simulation model is proposed to evaluate the performances of power line communication (PLC) in indoor environment. The power cable used as PLC transmission vector is modeled by the multiconductor transmission line (MTL) theory. The MTL electrical parameters are obtained by the finite element method (FEM) analysis of the cable cross-section. The MTL network is modeled by two different approaches based on connection of the MTL chain matrices in frequency domain and on a series cascade of lumped pi sections in time domain. The comparisons of the calculated results with measurements are presented in the frequency range 1-30 MHz for two different configurations of the power cable network. Finally, the channel characterization for several load conditions and realistic network configurations are also performed.