On the Spatial Averaging of Multiple Narrowband Electromagnetic Field Measurements: Methods and Uncertainty Estimation

Methods of computational prediction can be used or specific measurements have to be performed for the estimation of human exposure to nonionizing electromagnetic fields at a certain place. According to the exposure standards, the predicted or the measured values have to be spatially averaged in an area representing the dimensions of the human body and compared with the adopted maximum permissible levels of exposure. In this paper, methods for spatial averaging nonionizing electromagnetic fields are discussed. Moreover, methods for estimating spatial average uncertainty of the total field strength values and of the summation of exposure quotients when narrowband measurements are performed in a multiple-frequency environment are proposed. Furthermore, since maximum field values have to be averaged according to the most widely accepted exposure standards, the traffic-dependent power level variation issue is also addressed. In particular, for GSM systems, an extrapolation method to the maximum possible field levels using data from real-time measurements when the frequency allocation per operator base station and the spatial distribution of the exposure sources are unknown is also proposed. Finally, an uncertainty estimation procedure associated to the extrapolated levels is presented.