An on-site dosimetry system for safety assessment using spatial harmonic components of incident EM fields

Abstract

We have previously reported on a portable dosimetry system based on a mixed FDTD-integral equation approach for rapid on-site evaluation of the SAR distributions in an anatomically-based model of the human body immersed in a complex electromagnetic environment (Lazzi and Gandhi). In the present paper, we present a different approach where we use the pre-stored responses of the human model for spatial harmonic components varying as cos (m/spl pi/x/A) cos (n/spl pi/z/B) along the horizontal (x) and vertical (z) directions, respectively. Here the dimensions A and B are taken to be larger than the dimensions of the human body along x and z directions, respectively. Unlike the Lazzi and Gandhi spatial impulse response method, we find that no more than 15 spatial harmonic components are needed to get an accuracy of less than /spl plusmn/20 percent (l dB) in the whole-body-averaged and peak 1-g SARs needed for safety compliance testing against the IEEE safety guidelines. As expected, only for very narrow area exposures as compared to the dimensions of the human body, does one need more than 15 spatial harmonic components for the desired accuracy particularly for the peak 1-g SARs. However, these situations are not very typical of the commonly encountered EM environments and spatially broader whole-body exposures are normally encountered.