Simple assessment of Specific Absorption Rate (SAR) for MIMO terminals

Evaluating SAR for multi-antennas is difficult and impractical due to the arbitrary power allocation and phase of the electric fields from different antennas causing the total field to change randomly. In this context, a simple approach was recently proposed for assessing SAR when more than one antenna is transmitting simultaneously. The metric of time averaged simultaneous peak SAR (TASPS) was derived for the purpose of showing that only the stand-alone SAR for each antenna needs to be evaluated in order to verify if the SAR for multi-antenna transmissions also stays within the exposure limit. In this paper, we briefly review the derivation and illustrate the physical mechanism underlying this result for a two-antenna prototype using stand-alone and simultaneous SAR distributions.