Applicability of SAR Estimation Method Based on 2-D Scanned E-Fields to Determine Maximum Average SAR for Multi-antenna Transmitters

INTRODUCTION A multi-antenna transmitter, e.g. in Multi-Input Multi-Output (MIMO) systems, will be implemented in the user equipment (UE) of mobile communication systems in the near future [1]. Applying the standardized procedures [2][3] for obtaining the maximum average Specific Absorption Rate (SAR), which is an evaluation index for RF exposure to human, requires the measurement of the three-dimensional SAR distribution prior to determining the average SAR in each case if weighting coefficients are variable. Therefore, this process is expected to be time consuming. Procedures for estimating the SAR for a multi-antenna transmitter were proposed in [4] and [5], in which the maximum SAR at each point can be obtained. On the other hand, we proposed a measurement procedure that can obtain the SAR distributions for arbitrary weighing coefficients of antennas using a short measurement process [6]. This paper shows the numerical verification of our proposal using four dipole antennas and a flat phantom.