Age-dependence of electromagnetic power and heat deposition in near-surface tissues in emerging 5G bands

With the development of 5th generation (5G) mobile networks people of different ages will be exposed in the upper part of the microwave spectrum. From the perspective of non-ionizing radiation dosimetry, an accurate analysis of age-dependent electromagnetic power deposition and resulting heating is required. In this study, we evaluate the effect of age on exposure at 26 GHz and 60 GHz. A near-surface tissue model illuminated by a plane wave is used to asses the exposure considering both frequency-independent and frequency-dependent limits. The age-related variation of the skin thickness and tissue electromagnetic properties has been considered. Moreover, the blood flow decrease rate has been taken into account to assess the age-dependent heating. Our results demonstrate that the overall variations of the power density, specific absorption rate (SAR) and heating in the near-surface tissues are limited to about 10–15%. These variations are mainly due to the tissue permittivity and blood flow change with age. In contrast to the transmitted power density that increases with age, the peak SAR decreases at both frequencies. The peak steady-state heating increases from 5 to 70 years old by roughly 11% at 26 GHz and 13% at 60 GHz

A conformal, dynamic pattern-reconfigurable antenna using conductive textile-polymer composite

A conformal antenna with electronically tuning capability of its radiation pattern between broadside and monopole-like patterns is proposed. The antenna is based on a proximity-fed circular patch, loaded with a ring patch and four rectangular slots. The design is planar without any use of rigid shorting posts or complex feeding network. The reconfigurability is achieved by activating and deactivating the slots using PIN diodes, to switch between TM02 (monopole-like mode) and perturbed TM02 distributions (broadside mode) of the antenna. For conformability, the antenna is fabricated using highly flexible PDMS-conductive fabric composite. All the antenna parts, including the RF switches, wires, and DC biasing circuit are fully encapsulated by PDMS to provide resilience against deformation and harsh environment. Investigations on the RF performance and mechanical stability of the antenna were conducted. Under various bendings, it was demonstrated that all the antenna components, including those for electronic switching, remained intact and in working order even under radius bending of 30 mm, thus maintaining good pattern reconfigurability and overall performance. When bent, the measured results at 5.2 GHz show a stable radiation performance relative to those of the flat case (i.e., maximum gain of 2.9 dBi and efficiency of 64% in broadside mode, corresponding to 1.75 dBi and 52% in monopole-like mode). To the best of our knowledge, all these features have never been demonstrated in previously published pattern reconfigurable antennas

Wireless power transfer Exposure assessment for grounded and ungrounded human body

International audienceThis study compares the exposure of a grounded and ungrounded human body to a representative resonant wireless power transfer (WPT) system. A Duke human body model is adopted all along the paper. Exposure levels with respect to the ICNIRP basic restrictions are assessed as a function of the distance between the WPT system and the ground, and reported in terms of dosimetric quantities E99, J1cm2, as well as local and whole body SAR. Maximum allowable input power is computed for the considered scenarios. The results demonstrate that, peak dosimetric values are much higher in grounded than ungrounded scenarios independently of the distance of the WPT system from the ground. For the grounded cases, as the WPT system gets closer to the ground, higher exposure levels are induced inside the body in terms of J1cm2 and SAR10g as a difference to E99 and SARwb. Moreover, SAR10g is found to be the most restrictive dosimetric quantity. © Institution of Engineering and Technology.All Rights Reserved

Design Methodology of a Printed WPT System for HF-Band Mid-Range Applications Considering Human Safety Regulations

International audienceA methodology for the design of printed magnetically coupled resonant wireless power-transfer (WPT) systems is proposed. The design methodology aims at a well-matched system with a maximized power-transfer efficiency for mid-range applications. The system consists of two identical resonant coils driven by high-quality factor loops. The proposed design criteria allows obtaining maximum achievable transfer efficiency and impedance matching at any defined distance without any external matching circuits connected to the driven loops. For validation purposes, a printed WPT system at 10 MHz is fabricated targeting 1-m distance between the transmitting and receiving sides. Its performances in terms of reflection and transmission coefficients, as well as in terms of generated electric and magnetic fields, have been characterized numerically and experimentally. The impact of human body presence on the system has also been investigated observing the splitting in two frequencies of the common resonant frequency of the coils. A dosimetric study has been conducted using a detailed high-resolution anatomical human body model and considering E99, J1 cm2, and specific absorption rate (SAR) (local and whole body averaged SAR) as exposure metrics. It has been observed that peak exposure levels appear in different tissues depending on the body location. Compliance with the international commission on nonionizing radiation protection (ICNIRP) reference level as well as basic restrictions has been studied followed by computing the maximum allowable input power. It has been found that, with the body located 1 m away from the transmitting coil, the maximum allowable input power satisfying E99 is in the order of MW, whereas it reduces to tens of kilowatt when considering SAR and J1 cm2. The latter has been noticed to be the most restrictive dosimetric quantity. © 2016 IEEE

Wireless power transfer in presence of a body

International audienceA study of interactions between a human body and a wireless power transfer system has been presented. The system consists of two identical resonant coils driven by high quality factor loops. Four different exposure scenarios are considered using a high-resolution anatomical body model. Local specific absorption rate averaged over 10g of tissue is evaluated. Compliance with respect to the ICNIRP basic restrictions is also investigated followed by computing the maximum allowable input power. © 2016 IEEE

Local Dosimetry Applied to Wireless Power Transfer Around 10 MHz Dependence on em Parameters and Tissues Morphology

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Wireless power transfer: Are children more exposed than adults?

International audienceAiming at comparing the exposure levels among children and adults, this paper investigates the exposure due to a representative wireless power transfer system in three different human body models, i.e. adult male and female as well as a child. A dosimetry study has been performed to evaluate the exposure levels with respect to the ICNIRP basic restrictions. Differences in terms of dosimetric quantities (E99, J1cm 2, and local and whole body SAR) has been assessed and reported. Maximum allowable input power has been computed for a representative scenario. It has been found that, for the considered scenario, the exposure due to a resonant WPT system in a child is the same or lower than in an adult. Moreover, the impact of the body dimensions is more pronounced for peak RMS values of E99 and J1cm 2 compared to those obtained for SAR10g and SARwb· J1cm 2 is found to be the most restrictive dosimetric quantity for both the child and adults. © 2017 Euraap

Publisher Correction: Age-dependence of electromagnetic power and heat deposition in near-surface tissues in emerging 5G bands (Scientific Reports, (2021), 11, 1, (3983), 10.1038/s41598-021-82458-z)

International audienceThe original version of this Article contained typographical errors. In Figure 5b,d the solid lines representing the analytic results did not display correctly. The original Figure 5 and accompanying legend appear below. The original Article has been corrected

Computational microdosimetry at cellular level at millimeter wave frequencies

International audienceA microdosimetric study is performed on a canonical biological cell model in the 60-GHz band. Complex permittivity data of dielectric models of the membrane, cytoplasm, and extracellular medium at microwaves has been extrapolated to millimeter-wave (mmWave) frequencies. A quasi-static electromagnetic (EM) analysis is employed to solve the Laplace equation numerically. The results demonstrate that cellular and sub-cellular membranes are no longer able to shield the intracellular organelles at mmWave frequencies, as it is the case at lower frequencies, and almost 100% of the electric field penetrates inside the cell, reaching intracellular organelles. © 2020 IEEE