Measurement of the maximum SAR in a spherical phantom when operating a mobile phone near a metallic wall

The aim of this paper is to present an experimental investigation of the specific absorption rate (SAR) in a spherical phantom head when operating a mobile phone close to a metallic wall. The mobile phone is modeled as a half-wavelength dipole antenna. The effect of the wall on the peak 10-g SAR and input characteristics of the antenna for two wall orientations are measured. The antenna is set to transmit maximum output power of 250 mW at 900 MHz. A slowly decaying sinusoidal form of the peak 10-g SAR curves, which has been predicted by numerical simulation from several authors including ourselves, is confirmed experimentally for the first time. Under the valid antenna-wall distances used in this work, maximum peak 10-g SAR increase of 7% over the free space value was recorded at the distance of 394 mm away from the wall. Simulated results obtained by the FDTD technique are also presented. Good agreement between the measured and simulated results is obtained.