Abstract of "Evaluation of the SAR Distribution
in the Human Head for Cellular Phones Used in a Partially Closed Environment"
The purpose of this paper is to calculate the SAR distribution in a human head exposed to the electromagnetic field emitted from a hand-held cellular phone operating in the 900 MHz range in a partially closed environment. The environment could be, for example, the interior of a car, a condition of exposure which is largely diffused nowadays. The presence of reflecting surfaces near the phone modifies the current distribution on, and the emitting properties of, the phone antenna. Therefore, the distribution of the absorbed power inside the head is different from that absorbed in the free space exposure condition.
The Finite-Difference Time-Domain (FDTD) method has been used to evaluate the SAR in a realistic, anatomically based model of the human head for different antenna-handset configurations and for different antenna-head distances. The environmental effects have been simulated through partially or totally reflecting walls located in various positions with reference to the phone.
It is found that the presence of a horizontal reflecting wall over the head decreases the SAR values in the part of the head directly exposed to the phone antenna, while increases the SAR values in the part not directly exposed. On the contrary, the presence of a vertical wall, located in proximity of the phone and parallel to it, raises the SAR values everywhere into the head.