SAR DISTRIBUTIONS IN A HUMAN-MODEL EXPOSED TO ELECTROMAGNETIC NEAR-FIELD BY A SHORT ELECTRIC-DIPOLE

The SAR distributions over a homogeneous human model exposed to a near field of a short electric dipole in the resonant frequency region wer e calculated with the spatial resolution of 1 cm(3) which approximated 1 g tissue by using the FDTD method with the expansion technique. The dependences of the SAR distribution on the distance between the model and the source and on frequency were investigated. It was shown that the large local SAR appeared in the parts of the body nearest to the s ource when the source was located at 20 cm from the body, whereas the local SAR were largest in the narrow sections such as the neck and leg s when the source was farther than 80 cm from the model. It was also s hown that, for the near-held exposure in the resonant frequency region , the profile of the layer averaged SAR distribution along the main ax is of the body of the human model depended little on frequency, and th at the SAR distribution in the section perpendicular to the main axis of the human body depended on frequency. The maximum local SAR per gra m tissue over the whole body model was also determined, showing that t he ratios of the maximum local SAR to the whole-body averaged SAR for the near-field exposure were at most several times as large as the cor responding ratio for the far-field exposure, when the small source loc ated farther than 20 cm from the surface of the human model.