The scaled SAM models and SAR for handset exposure at 835 MHz

The relation between local specific absorption rate (SAR) and head size was investigated using a specific anthropomorphic mannequin (SAM) model. We assumed that the shell of the SAM model has the same properties with the head-equivalent tissue. The model was scaled to 80-100% at intervals of 5%. Five handsets with a monopole antenna operating at 835 MHz were placed in the cheek position against the scaled SAM models. They have different antenna length, antenna position, body size, or external material. SAR distributions for the scaled SAM models were computed using the finite-difference time-domain technique. Input impedance, antenna-accepted power and radiation characteristics of the handset under the test position and local SARs were compared for the different head sizes. It is found that the head size did not change significantly the overall values of peak 1 g-SAR and 10 g-SAR for the same power accepted by the handset antenna, while for the same radiation power, the larger head requires the higher antenna-accepted power and produces the higher 1 g-SAR and 10g-SAR.