Study of the influence of the hand on the Specific Absorption Rate evaluation of mobile phones

The influence of the hand on the SAR (Specific Absorption Rate) assessments of mobile phones is investigated. A possible increase of the SAR value in the presence of the hand has been reported by several authors but the electromagnetic phenomenon is still unexplained. Numerical simulations are herein performed using four different mobile phones using the SAM (Specific Anthropomorphic Mannequin) phantom and a hand model at three different frequencies in order to understand the key parameters - mobile phone design, antenna type, frequency, etc. - which may influence the SAR value in the presence of the hand. An increase of the SAR is observed for one mobile phone model at 1950 MHz and for a configuration such that the distance between the antenna and the palm of the hand is about 20 mm. Additional numerical simulations and measurements performed using a dipole antenna placed in-between a flat head phantom and a flat hand phantom confirm that an increase of the SAR is obtained for some specific values of the distance between the antenna and the hand at a given frequency.