Abstract-A compact wearable Personal DistributedExposimeter is proposed, sensing the power density of incident radio-frequency (RF) fields on the body of a human. In contrast to current commercial exposimeters, our Personal Distributed Exposimeter, being composed of multiple compact personal wearable RF exposimeter sensor modules, minimizes uncertainties caused by the proximity of the body, the specific antenna used and the exact position of the exposimeter. For unobtrusive deployment inside a jacket, each individual exposimeter sensor module is specifically implemented on the feedplane of a textile patch antenna. The new wearable sensor module's high-resolution logarithmic detector logs RF signal levels. Next, on-board flash memory records minimum, maximum and average exposure data over a time span of more than two weeks, at a one-second sample period. Sample-level synchronization of each individual exposimeter sensor module enables combining of measurements collected by different nodes. The system is first calibrated in an anechoic chamber, and then compared to a commercially available single-unit exposimeter. Next, the Personal Distributed Exposimeter is validated in realistic conditions, by measuring the average RF power density on a human during a walk in an urban environment and comparing the results to spectrum analyzer measurements with a calibrated antenna.
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
This paper describes, for the first time, the procedure for the full design, calibration, uncertainty analysis, and practical application of a personal, distributed exposimeter (PDE) for the detection of personal exposure in the Global System for Mobile Communications (GSM) downlink (DL) band around 900 MHz (GSM 900 DL). The PDE is a sensor that consists of several body-worn antennas. The on-body location of these antennas is investigated using numerical simulations and calibration measurements in an anechoic chamber. The calibration measurements and the simulations result in a design (or on-body setup) of the PDE. This is used for validation measurements and indoor radio frequency (RF) exposure measurements in Ghent, Belgium. The main achievements of this paper are: first, the demonstration, using both measurements and simulations, that a PDE consisting of multiple on-body textile antennas will have a lower measurement uncertainty for personal RF exposure than existing on-body sensors; second, a validation of the PDE, which proves that the device correctly estimates the incident power densities; and third, a demonstration of the usability of the PDE for real exposure assessment measurements. To this aim, the validated PDE is used for indoor measurements in a residential building in Ghent, Belgium, which yield an average incident power density of 0.018 mW/m².
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