Whole-Body Averaged Specific Absorption Rate Estimation Using a Personal, Distributed Exposimeter

Abstract

For the first time, a body area network (BAN) is used to construct a personal, distributed exposimeter (PDE), which can measure the whole-body averaged specific absorption rate ( ${{\rm SAR}_{\rm wb}}$ ) in real life, together with the incident power density ( ${{\rm S}_{\rm inc}}$ ). The BAN consists of four textile antennas with integrated radio frequency receiver nodes tuned to the Global System for Mobile Communications (GSM) 900 downlink band. Calibration measurements at 942.5 MHz, using a human subject, are performed in an anechoic chamber. These are combined with numerical simulations to estimate both ${{\rm SAR}_{\rm wb}}$ and ${{\rm S}_{\rm inc}}$ from the averaged received power on the PDE. The PDE has 50% prediction intervals of 3 dB on ${{\rm S}_{\rm inc}}$ and 3.3 dB on the ${{\rm SAR}_{\rm wb}}$ , caused by the presence of the human body, whereas the best single textile antenna in our measurements exhibits ${{\rm PI}_{50}}$ ’s of 7.1 dB on ${\rm {S}}_{{\rm {inc}}}$ and 5 dB on ${{\rm SAR}_{\rm wb}}$ . Measurements using the PDE are carried out in Ghent, Belgium, during which a median ${{\rm S}_{\rm inc}} = 47~\mu\hbox{W}/\hbox{m}^{2}$ and ${{\rm SAR}_{\rm wb}} = 0.25~\mu\hbox{W}/{kg}$ are measured.