Exposure of Insects to RadioFrequency Electromagnetic Fields from 2 to 120GHz

Bron: www.nature.com/articles/s41598-018-22271-3.pdf
Received: 27 September 2017
Accepted: 20 February 2018
Published: 2 March 208

Arno Thielens 1,2, Duncan Bell 3, David B. Mortimore 4, Mark K. Greco 5, Luc Martens1 & Wout Joseph 1

1 Department of Information Technology, Ghent University - imec, Ghent, B-9052, Belgium.
2 Department of Electrical Engineering and Computer Sciences, University of California Berkeley, Berkeley Wireless Research Center, Berkeley, CA, 94704, USA.
3 Department of Science and Technology, Faculty of Health and Science, University of Sufolk, Ipswitch, IP30AQ, United Kingdom.
4 Newbourne Solutions Ltd, Newbourne, Woodbridge, IP12 4NR, United
Kingdom.
5 Charles Sturt University, Medical Imaging, SDHS, Faculty of Science, Wagga Wagga, NSW 2678, Australia.

Insects are continually exposed to Radio-Frequency (RF) electromagnetic felds at diferent frequencies.
The range of frequencies used for wireless telecommunication systems will increase in the near future
from below 6GHz (2G, 3G, 4G, and WiFi) to frequencies up to 120GHz (5G). This paper is the frst
to report the absorbed RF electromagnetic power in four diferent types of insects as a function of
frequency from 2GHz to 120GHz. A set of insect models was obtained using novel Micro-CT (computer
tomography) imaging. These models were used for the frst time in fnite-diference time-domain
electromagnetic simulations. All insects showed a dependence of the absorbed power on the frequency.
All insects showed a general increase in absorbed RF power at and above 6GHz, in comparison to the
absorbed RF power below 6GHz. Our simulations showed that a shift of 10% of the incident power
density to frequencies above 6GHz would lead to an increase in absorbed power between 3–370%.

Conclusions
We investigated the absorbed radio-frequency electromagnetic power in four different real insects as a function of frequency from 2–120 GHz. Micro-CT imaging was used to obtain realistic models of real insects. These models were assigned dielectric parameters obtained from literature and used in finite-difference time-domain simulations. All insects show a dependence of the absorbed power on the frequency with a peak frequency that depends on their size and dielectric properties. The insects show a maximum in absorbed radio frequency power at wavelengths that are comparable to their body size. They show a general increase in absorbed radio-frequency power above 6 GHz (until the frequencies where the wavelengths are comparable to their body size), which indicates that if the used power densities do not decrease, but shift (partly) to higher frequencies, the absorption in the studied insects will increase as well. A shift of 10% of the incident power density to frequencies above 6 GHz would lead to an increase in absorbed power between 3–370%. This could lead to changes in insect behaviour, physiology, and morphology over time due to an increase in body temperatures, from dielectric heating. The studied insects that are smaller than 1 cm show a peak in absorption at frequencies (above 6 GHz), which are currently not often used for telecommunication, but are planned to be used in the next generation of wireless telecommunication systems. At frequencies above the peak frequency (smaller wavelengths) the absorbed power decreases slightly.


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