-In recent years, there has been an increasing public concern about possible health hazard resulting from exposure to electromagnetic (EM) waves. Much attention has been paid to the induced of SAR in the human head for exposure to EM waves emitted from commercial cellular phone antennas. Therefore, the computation of the electric fields and SAR generated by cellular phone inside a four-tissue phantom head model is presented in this paper. The phone was considered working at 900MHz to 1800MHz bands according to the Global System of Mobile Communication (GSM). The penetration of the E-fields and averaged SAR values in 1g and 10g of tissue were computed inside the model of human head using Finite Difference Time Domain (FDTD) technique. The E-fields and SAR are then evaluated using CST Microwave Studio as it capable to do an accurate 3D simulation. The CST Microwave Studio results show that magnitude of EM field decreases exponentially with the penetration distance at a rate specified by the attenuation constant, α. Besides, the SAR is affected by operational frequency of the phone and the distance of the antenna to the human head. An experimental technique on SAR distribution needs to be done to validate the results from simulation technique.

Abstract-Ultra wideband radio (UWB) is a promising technology that offers exceptional data rates for short range communication. This paper presents the analysis of the IEEE 802.15.4a UWB physical layer (PHY), a novel short range wireless communication technology, for wireless sensor network (WSN) applications. We analysed and compared the performance of the UWB PHY using the MIXIM framework for a discrete event based simulator called OMNeT++. In this context, we present the simulation and implementation of line of sight (LOS) and non line of sight (NLOS) channel models with a variety of configurations such as data rates, bandwidth and forward error correction. An analysis on bit error rate (BER) over distance will be discussed in order to evaluate the channels performance. The results will serve as a base for future studies on deploying IEEE 802.15.4a based sensor networks with specific characteristics.