NEWS
Nov 23, 2021

Intercomparison of Calculated Incident Power Density and Temperature Rise for Exposure From Different Antennas at 10–90 GHz

Kun Li, Yinliang Diao, Kensuke Sasaki, Alexander Prokop, Dragan Poljak, Vicko Doric, Jingtian Xi, Sachiko Kodera, Akimasa Hirata, and Walid El Hajj, IEEE Access 2021, Volume 9, pp. 151654–151666, online 13 November 2021; doi: 10.1109/ACCESS.2021.3126738

Recently, international exposure guidelines/standards for human protection from electromagnetic fields were revised. For frequencies between 6–300 GHz, the permissible incident power density is defined as the reference level, which is derived from a new metric “absorbed/epithelial power density”, based on thermal modeling. However, only a few groups have computed the power density and the resultant temperature rise at frequencies >6 GHz, where exposure conditions are different. This study presents the first intercomparison study of the incident power density and the resultant temperature rise in a human body exposed to different frequency sources ranging from 10 to 90 GHz. The aim of this intercomparison is to clarify the main causes of numerical calculation errors in dosimetry analyses through objective comparison of computation results from six organizations, performed with their numerical methods with various body and antenna models. The intercomparison results indicate that the maximum relative standard deviation (RSD) of peak spatially averaged incident power densities for dipole and dipole array antennas are <22.1% and <6.3%, respectively. The maximum RSD of the heating factor, which is defined as the ratio of the peak temperature elevation at the skin surface to the peak spatially averaged incident power density in free space, for dipole and dipole array antennas is <43.2% and <41.2%, respectively. The deviations in the heating factors caused by different body models and dielectric/thermal parameters are within 33.1% and 19.6% at 10 and 30 GHz, respectively, when the antenna-to-skin model distance is >5 mm. Under this condition (>5 mm), the deviation in the heating factors caused by different antenna models at 30 GHz does not exceed 26.3%. The fair agreement among the intercomparison results demonstrates that numerical calculation errors of dosimetry analyses caused by the definition of spatially averaged incident power density are marginal.

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

  • This study presents the first intercomparison of calculated spatially averaged incident power density and the resultant temperature rise in a simplified model of the human body exposed to different millimeter wave antennas, with the aim to clarify the main sources of numerical calculation errors in the dosimetry analysis
  • The numerical calculation errors – caused by the body model, the dielectric/thermal parameters, the antenna model, and the definition of spatially averaged incident power density – are small
  • Other factors, such as the antenna type, the separation distance between the antenna and the body model, and the numerical method, may give rise to relatively large discrepancies