Modeling and calculation of the specific absorption rate for multi-antenna mobile devices

With the fast development of portable wireless devices, more and more communication and entertainment functions are featured in cell phones and other mobile devices, many of which require the integration of multiple transmitting/receiving antennas into the limited space of the device. Since each radio antenna exposes the user to some level of electromagnetic radiation, if several radios are operating concurrently, the total exposure could be cumulative, which would become a great concern. To quantify the human exposure to the RF radiation, the specific absorption rate (SAR) is introduced as a measure. Regulatory agencies have standards limiting the maximum SAR to ensure safety. In order to comply with the regulations, the SAR induced in the human head and body should be evaluated by experimental measurement or numerical simulation. When there are multiple transmitting antennas, the measurement or the simulation could take a very long time due to the fact that each phase combination needs to be taken into account. Thus a fast method to evaluate SAR is desirable. In this work, we establish various SAR models to address this problem. We investigate the accuracy and parameter dependency of the SAR models, explore their applicability in the millimeter-wave regime, which could become the mainstream frequency band in the future, and utilize them in a fast SAR evaluation scheme