Multiple antennas working at a same frequency, such as Multi-Input Multi-Output (MIMO), beamforming, phased array antenna systems, are expected to play a key role in 5G wireless communications. As such devices are used near human body, there is an increasing demand to develop measurement methods and procedures for evaluating the specific absorption rate (SAR) of them in compliance tests for radio frequency radiation protection guidelines. In this paper, we present a fast technique for estimating the SAR of multiple-antenna transmitting devices such as mobile phones or the alike, which utilize two or more antennas in communication. SAR values for arbitrary relative phase combinations of the antennas at an observation point can be estimated from SAR measurements for several pre-defined relative phases. Experimental validations on different antenna configurations have been carried out to verify the proposed estimation method. We also discuss some challenging points in the estimation technique, and point out several key issues of SAR measurements for multiple-antenna devices.
展开▼
