Modal-based analysis of depth influence on SAR applied to the correlation study between averaged SAR and total dissipated power

Measurement campaigns have shown that the electric field due to a mobile handset in an homogeneous phantom globally decays exponentially with depth. The aim of this paper is to clarify this behavior, which is the basis of some fast SAR assessment techniques, so as to specify the relationship between total dissipated power in a phantom and SAR averaged in a given cube of liquid. To this purpose, a 2-D modal analysis of power absorption in cylindrical and flat phantoms is first presented. This analysis is extended to the 3-D case of a GSM mobile phone close to a flat phantom, by means of a simplified field modal expansion as well as numerical calculation