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Bioelectromagnetics. 2020 Feb;41(2):164-168. doi: 10.1002/bem.22244. Epub 2019 Dec 30.

Discussion on Spatial and Time Averaging Restrictions Within the Electromagnetic Exposure Safety Framework in the Frequency Range Above 6 GHz for Pulsed and Localized Exposures.

Author information

1
Foundation for Research on Information Technologies in Society (IT'IS), Zurich, Switzerland.
2
Department of Physics, Aristotle University of Thessaloniki, Thessaloniki, Greece.
3
Department of Physics, University of Malta, Msida, Malta.
4
Swiss Federal Institute of Technology (ETH), Zurich, Switzerland.

Abstract

Both the current and newly proposed safety guidelines for local human exposure to millimeter-wave frequencies aim at restricting the maximum local temperature increase in the skin to prevent tissue damage. In this study, we show that the application of the current and proposed limits for pulsed fields can lead to a temperature increase of 10°C for short pulses and frequencies between 6 and 30 GHz. We also show that the proposed averaging area of 4 cm2 , that is greatly reduced compared with the current limits, does not prevent high-temperature increases in the case of narrow beams. A realistic Gaussian beam profile with a 1 mm radius can result in a temperature increase about 10 times higher than the 0.4°C increase the same averaged power density would produce for a plane wave. In the case of pulsed narrow beams, the values for the time and spatial-averaged power density allowed by the proposed new guidelines could result in extreme temperature increases. Bioelectromagnetics. 2020;41:164-168.

KEYWORDS:

human skin; millimeter-wave; near-field; power density; temperature increase

PMID:
31885092
DOI:
10.1002/bem.22244

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