Openings

Post-Doctoral Position

5G at millimeter waves: contribution to design of a near-field dosimetry system in the 60-GHz band for user exposure assesment

Research Fields: millimeter waves, microwave modeling and systems, electromagnetic dosimetry, antennas and probes, tissue-equivalent models

Research Laboratory: Institute of Electronics and Telecommunications of Rennes (IETR), UMR CNRS 6164, University of Rennes 1, Rennes, France.

Expected Starting Date and Duration: First semester 2020 (18 months)

 

Research environment

The candidate will join Electromagnetic Waves in Complex Media Team (WAVES, www.ietr.fr/WAVES.html) of the IETR. Our research activities in biomedical electromagnetics cover a wide spectrum of fundamental and applied research spreading from multi-physics and multi-scale modeling to advanced technologies for body-centric wireless communications. The team was at the origin of pioneering innovations in biomedical electromagnetics, including the first mm-wave tissue-equivalent phantoms, novel reflectivity based surface phantom concept, new broadband multi-physics characterization technique for Debye-type materials, innovative mm-wave textile antennas for smart clothes, ultra-robust miniature implantable UHF antennas, and the first mm-wave reverberation chamber.

Research project

Context

Continuous development of mobile terminals, such as smartphones, tablets, and body-worn electronic devices, has increased the wireless data traffic that keep growing due to video streaming applications and cloud computing. The increasing need in high-performance mobile communications leads to a fast development of next-generation heterogeneous 5G cellular mobile networks. To meet the bandwidth requirement, the upper limit of the spectrum used for 5G has shifted towards the millimeter-wave (MMW) band. In coming years, MMW mobile broadband systems will be integrated in 5G networks. The new use cases and services will involve interaction of radiating devices with the human body, both in terms of the human body impact on the performance of wireless devices as well as in terms of user exposure to electromagnetic fields. This includes near-field exposure by wearable and mobile devices operating in vicinity of the human body. Radiated powers of the user terminals may result in locally very high exposure levels under near-field exposure conditions due to localized absorption at MMW. The existing standards and dosimetry methods, that were originally developed for 3G/4G broadband cellular network technology operating in sub-6GHz range, are not scalable to MMWs due to the strong absorbance of EM waves at high frequencies. This motivates research towards new solutions for accurate dosimetry in the near-field MMW scenarios aimed at anticipating the forthcoming deployment of 5G networks.

Objectives

The project deals with the design, optimization and experimental characterization of a new MMW dosimetry system and the associated methodology for near-field exposure assessment.

Project summary

Existing experimental MMW dosimetry techniques are limited to electromagnetic field measurements using free-space probes in vicinity of wireless devices. These solutions do not account for a potential increase of exposure levels due to the presence of human body and may cause underestimation of exposure levels. To overcome these limitations, we propose an alternative approach based on a solid skin-equivalent phantom model that was recently introduced by our research team in the 60-GHz band [1].  The phantom comprises a thin layer of a composite dielectric material (PDMS saturated with the carbon powder) deposited on a metallic ground plane. The properties of the dielectric layer (thickness, composition) are optimized to reproduce the reflection coefficient from the human skin. This solid tissue-equivalent model will be used as a starting point to design a MMW dosimetry system for measurements of power density accounting for perturbation of the EM fields radiated by a MMW wireless device in presence of the human body. The proposed system will integrate two key functionalities: (1) it will accurately reproduce the reflection coefficient of human skin and (2) it will enable retrieval of the power density based on the field measurements inside the tissue-equivalent phantom.

 

1) A. R. Guraliuc, M. Zhadobov, O. De Sagazan, R. Sauleau. Solid phantom for body-centric propagation measurements at 60 GHz. IEEE Transactions on Microwave Theory and Techniques, 62(6), pp. 1373–1380, Mai 2014.

2) A. Guraliuc, M. Zhadobov, R. Sauleau, L. Marnat, L. Dussopt. Near-field user exposure in forthcoming 5G scenarios in the 60-GHz band. IEEE Transactions on Antennas and Propagation, 65(12), pp. 6606–6615, Dec. 2017.

3) M. Zhadobov, C. Leduc, A. Guraliuc, N. Chahat, R. Sauleau. Antenna / human body interactions in the 60 GHz band: state of knowledge and recent advances. State-of-the-Art in Body-Centric Wireless Communications and Associated Applications, IET, pp. 97–142, Jun. 2016.

Job description

  • Conduct research and contribute to the development of the experimental setup for MMW dosimetry
  • Propose and evaluate technical solutions on various aspects of the project including numerical simulations and experimental works
  • Investigate different antennas solutions for near-field measurements
  • Simulate (using commercial software, like CST) the EM wave scattering by and propagation through metal-dielectric structures (multi-layer and/or periodic)
  • Contribute to a proof-of-concept experiment aimed at implementation and characterization of the developed solutions

Candidate

Education: PhD degree or equivalent experience.

Background: Electromagnetics, antenna design, microwave design / measurements, numerical modeling, simulations. Knowledge in electronics is welcome but not mandatory.

How to apply

To apply please send your CV, motivation letter, reference letters (optional), and a copy of your PhD diploma to maxim.zhadobov@univ-rennes1.fr