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

Abstract

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 (SAR wb ) in real life, together with the incident power density (S inc ). The BAN consists of 4 textile antennas with integrated radio frequency receiver nodes tuned to the Global System for Mobile Communications 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 SAR wb and S inc from the averaged received power on the PDE. The PDE has 50% prediction intervals of 3 dB on S inc and 3.3 dB on the SAR wb , caused by the presence of the human body, whereas the best single textile antenna in our measurements exhibits PI 50 's of 7.1 dB on and 5 dB on SAR wb Measurements using the PDE are carried out in Ghent (Belgium), during which a median S inc = 47 μW/m² and SAR wb = 0.25 μW/kg are measured.Index Terms-specific absorption rate, radio frequency, electromagnetic fields, exposure assessment, finite-difference time-domain simulations

Measuring personal exposure from 900MHz mobile phone base stations in Australia and Belgium using a novel personal distributed exposimeter

“…The corresponding value of the PI50 for antenna aperture of the PDE was 3.3 dB, which is much lower than measured in our study for the individual antennas (i.e.13.6 dB, 6.5 dB, and 6.1 dB). The value was also lower than that reported for single antennas in the same frequency band (Thielens et al, 2013(Thielens et al, , 2015cVanveerdeghem et al 2015). This indicates that averaging over multiple antennas on the body reduces the variation on the antenna aperture.…”

“…The PDE was connected to complementary receiver electronics (Vanveerdeghem et al, 2015) that registered the received power on the antennas. The Einc (incident electric-field strength) can be determined from the received power on the PDE, using the effective antenna aperture (AA) of the set of antennas (Thielens et al, 2015b(Thielens et al, , 2015c). Onbody calibration was performed to determine the AA.…”

“…In this study, we used established on-body calibration procedures (Thielens, 2015a(Thielens, , 2015b(Thielens, , 2015c(Thielens, , 2013Vanveerdeghem et al, 2015). The calibration took place in an anechoic chamber with a transmitting antenna (TX) on one side of the chamber and a rotational platform on the other side.…”

“…In this paper, no assumptions were made on the incident polarization, since the PDE was to be used in different microenvironments that all have their own characteristic polarization distribution. Whereas Vanveerdeghem et al (2015) (6.6 cm²) and Thielens et al (2015c) used the PDE only in an urban environment and consequently a-priori assumptions could be made on incident polarizations. However, the antenna aperture is in the same order of magnitude and realistic for this type of on-body antenna (Thielens et al, 2015c;Vanveerdeghem et al, 2015).…”

“…Whereas Vanveerdeghem et al (2015) (6.6 cm²) and Thielens et al (2015c) used the PDE only in an urban environment and consequently a-priori assumptions could be made on incident polarizations. However, the antenna aperture is in the same order of magnitude and realistic for this type of on-body antenna (Thielens et al, 2015c;Vanveerdeghem et al, 2015). The corresponding value of the PI50 for antenna aperture of the PDE was 3.3 dB, which is much lower than measured in our study for the individual antennas (i.e.13.6 dB, 6.5 dB, and 6.1 dB).…”