Topic

Study on the influence of antenna topologies and topologies of entire devices of wireless communication terminals operated near the body on the resulting SAR values

Start

01.11.2006

End

31.10.2007

Project Management

University of Wuppertal

Objective

The goal of this project was to determine exposures to electromagnetic fields originating from wireless communication terminals operated near the human body. The exposure was expressed in terms of the specific absorption rate (SAR) rather than in terms of external electromagnetic field intensities. Furthermore it was examined, which potential for minimizing the SAR is offered by modifications of the devices, especially by changing the antennas’ positions and geometries, but without diminishing the communication characteristics of the devices.

The project contributed to the research programme "miniWatt II" funded by the German Federal Ministry of Education and Research (BMBF). It focused on appliances operated near the body. Equipment that is usually used with contact to the body like mobile phones, was analyzed in another part of the miniWatt II programme.

Results

The results of the project can be found in the final report, which is available as PDF-file in German (4,165 KB).

Conclusions

Regarding exposures originating from sources operated near the human body the project contributed significantly to the data available. So far scenarios have been characterized by intensities of external field strengths mainly. In this project exposure has been determined consistently by means of high-resolution anatomical models of the human body in terms of SAR. The results contain valuable information on the relationship between whole-body and maximum localized SAR levels in different scenarios and at different frequencies.

The results of the study show that a reduction of whole-body SAR by more than 80% can be achieved without a deterioration of the transmission quality (assessed using the 'mean effective gain' MEG). In contrast, minimizing the SAR by distributing the total power to multiple antennas was found to be unfavourable since - due to field interference effects in the near-field - the tolerances for the optimum position of the terminals are very small. Yet, this is no hindrance for achieving a reduction of SAR by additional use of MIMO technologies which allow an overall decrease of the power levels. Concerning MIMO technology and its potential with respect to exposure minimization, the final results of the “miniWatt II” project are expected to provide additional information on this matter.