Jul 5, 2011

Estimation Formulas for the Specific Absorption Rate in Humans Exposed to Base Station Antennas

Marie-Christine Gosselin, Günter Vermeeren, Sven Kühn, Valpré Kellerman, Stefan Benkler, Tero M. I. Uusitupa, Wout Joseph, Azeddine Gati, Joe Wiart, Frans J. C. Meyer, Luc Martens, Toshio Nojima, Takashi Hikaje, Quirino Balzano, Andreas Christ, Niels Kuster, IEEE Transactions on Electromagnetic Compatibility, Volume 53, Issue 4, pp. 909–922, November 2011, online June 9

In this study, approximation formulas for the whole-body average specific absorption rate (SAR) and the peak spatial SAR of human bodies using readily available basic antenna parameters have been developed. The formulas can be used for adults standing in the radiating near field of base-station antennas operating between 300 MHz and 5 GHz, at distances greater than 200mm. It is shown that the 95th-percentile absorption for the human population can be well approximated by the absorption mechanism and statistical data of weight, height, and body-mass index of the human population. The validation was performed numerically using three anatomical human models (Duke, Ella, and Thelonious) exposed to 12 generic base-station antennas in the frequency range 300 MHz to 5 GHz at six distances between 10mm and 3m.

The scientific and technical impact of the study can be summarized as:

  • The service provider must provide a distance to the antenna from where the exposure is below the safety limits. Until now it was based either on free-space electromagnetic fields or SAR measurements. The former leads to very conservative exposure estimates, whereas the latter is technically challenging. 
  • This study has identified the absorption mechansim in the near-field of base station antennas
  • The derived approximation formula enables conservative exposure estimations as a function of distance from the antenna using generally known antenna parameters and with minimal overestimation
  • The results have already been integrated in the latest IEC standard PT62232 approved in 2011


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