CHARACTERISTICS OF THE SAR DISTRIBUTIONS IN A HEAD EXPOSED TO ELECTROMAGNETIC-FIELDS RADIATED BY A HAND-HELD PORTABLE RADIO

This paper presents characteristics of the specific absorption rate (S AR) distributions calculated by tile finite-difference time-domain (FD TD)) method using a heterogeneous and realistic head model and a reali stic hand-held portable radio model. The difference between the SAR di stributions produced by a 1/4-wavelength monopole antenna and those pr oduced by a 1/2-wavelength dipole antenna is investigated, The depende nce of the maximum local SAR on he distance d(a) between the auricle o f the head and tile antenna of the radio is evaluated, It is shown tha t the maximum local SAR decreases as the antenna length extends front 1/4 to 1/2 of the wavelength. The maximum local SAR's in a head model with auricles are larger than those in one without auricles. The depen dence of the SAR on the electrical inhomogeneity of the tissues in the head model is not significant with regard to the surface distribution and the maximum local SAR when the radio is near the head, IL is also shown that the maximum local SAR is not strongly dependent oil the po sition of the hand when the hand does mot shade the antenna, Furthermo re, the SAR's experimentally measured in a homogeneous head phantom ar e compared with the calculated SAR's.