Vol. 63, n° 1-2, January-February 2008
Content available on Springerlink
Joe Wiart, France Télécom R&D, France
Soichi Watanabe, National Institute of Information and Technology, Tokyo, Japan
Luis M. Correia, Instituto Superior Tecnico, Lisboa, Portugal
J. Wiart, S. Watanabe, L.M. Correia
Development of a numerical model connecting electromagnetism, thermal and hydrodynamics to analyse in vitro exposure system
M. Cueille, A. Collin, C. Pivain, Ph. Leveque
XLIM-UMR CNRS, No. 6172-123 avenue Albert Thomas, 87060 Limoges cedex, France
Abstract For bioelectromagnetic studies, a complete dosimetry is essential for optimised experiments and for analysis of the biological results. In this paper, we focused on the numerical dosimetry based on electromagnetic, thermal and convection simulations. The finite difference time domain (FDTD) method is used to obtain electromagnetic fields and specific absorption rate (SAR) distributions. Often metallic losses exist and cannot be neglected, and they are considered with SAR spatial distribution to evaluate temperature elevation. Time-scaled algorithms of heat transfer equation and incompressible Navier-Stokes equations applied to in vitro bioelectromagnetic studies are presented. For hydrodynamic thermal convection, the biological medium density has to be considered variable and the heat masses can move. Two different in vitro exposure systems are presented. A test tube with high temperature gradient induced in the biological medium is studied and illustrate convection phenomena. A wire patch cell with metallic elements highlights the role of metallic losses in the increase of temperature.
Keywords Multi-physic . Dosimetry . Specific absorption rate . Thermal conduction . Thermal convection
Analysis of the numerical One-Step method for the study applied on bio electromagnetics
Jessica Silly-Carette1, David Lautru2, Man-Faï Wong1, J. Wiart1 and Victor Fouad Hanna2
1 France Telecom RESA/FACE/IOP, 92794 Issy les Moulineaux Cedex 09, France
2 UPMC, 4 place Jussieu, F-75005 Paris, France
Abstract The development of wireless technologies arises important questions about the effects of the wave propagation in the human body. To study accurately these effects, we have to use rigorous numerical methods. In this paper, we present and analyze the One-Step time domain method. This method, which was proposed by De Raedt [Phys Rev E 67(056706):1-12, 2003] for lossless media, is known to be unconditionally stable and so it can be used for applications for which the Courant-Friedrich-Levy (CFL) stability condition can be a limiting factor, e.g., for bioelectromagnetic applications. The numerical dispersion and the insertion of lossy media in the One-Step method are evaluated. The perfectly matched layer (PML) absorbing conditions are also introduced in our study.
Keywords One-Step method . Dispersion . Lossy media . PML absorbing conditions . FDTD method
Design, modelisation and optimisation of high efficiency miniature E-field probes performed on 3D ceramic prisms for SAR evaluation
Christian Person1, François Le Pennec1, Jérôme Luc2
1 GET-ENST Bretagne, LEST-CS 83818-29238, Brest, France
2 ANTENNESSA, Avenue La Pérouse, 29280 Plouzané, France
Abstract A comprehensive design methodology is proposed in this paper in order to optimise E-field probes used for evaluating the specific absorption ratio within liquid equivalent tissues exposed to radiofrequency signals. Hybrid analysis approaches are investigated, combining both electromagnetic (three dimensional) and circuit simulators. This design environment can therefore be considered for enhancing E-field detectors’ performances in terms of sensitivity, isotropy, dimensions and shape. Comparisons between simulations and measurements are presented and discussed.
Keywords SAR . E-field probe . Electromagnetic simulation . Schottky detector
Specific absorption rate assessment near a basestation antenna (2,140 MHz): some key points
Fabrice Lacroux, Emmanuelle Conil, Albert Cortel Carrasco, Azeddine Gati, Man-Faï Wong, Joe Wiart
France Telecom Research & Development Division, 38 rue du Général Leclerc, 92794 Issy Les Moulineaux cedex 9, France
Abstract In this paper, a numerical dosimetry study for a typical base-station antenna used in third generation system is presented. This study is based on the limits defined by the International Commission on Non-Ionizing Radiation Protection. The primary goal is to analyze the relationship between the antenna input powers required to reach the specific absorption rate (SAR) limit and those ones which are required to reach the power density limit. The secondary goal is to underline the key points which impact the local SAR in the case of such a directive antenna. Moreover, for these studies, two numerical approaches are used: the first one is only based on the finite difference time domain method and, in the second one, this algorithm is coupled with a method of moments simulator via a Huygens box. Investigations are made to ensure that a more suitable numerical approach is used.
Keywords Exposure assessment . Numerical dosimetry . FDTD . UMTS base-station antenna
SAR characterization inside intracranial tumors for case-control epidemiological studies on cellular phones and RF exposure
Nadège Varsier1,2, Kanako Wake2, Masao Taki1, Soichi Watanabe2, Toru Takebayashi3, Naohito Yamaguchi4, Yuriko Kikuchi3
1 Department of Electrical Engineering, Tokyo Metropolitan University, 1-1 Minami-Osawa, Hachioji-shi, Tokyo 192-0397, Japan
2 National Institute of Information and Communications Technology, Nukuikitamachi 4-2-1, Koganei, Tokyo 184-8795, Japan
3 Department of Preventive Medicine and Public Health, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582, Japan
4 Department of Hygiene and Public Health, Tokyo Women’s Medical University, 8-1 Kawadacho, Shinjuku-ku, Tokyo 162-8666, Japan
Abstract Epidemiological studies investigating whether mobile phone use is related to cancer risk have been conducted in many countries. The purpose of the work reported here was to introduce the dose metric in the exposure assessment, taking into account the spatial distribution of exposure. Distributions of specific absorption rate (SAR) inside 275 cases of brain tumors (participants in the Japanese epidemiological study) were estimated. Phones had been classified into four categories based on SAR distributions and technical specifications. Results were found to be highly dependent on phone categories. Contralateral tumors were generally categorized as non-exposed tumors (max SAR <2.5% of max SAR in the brain) and, for any phone category, the maximum SAR in 75% of the ipsilateral tumors was less than 15% of the maximum SAR in the brain. Three new exposure indices combining the duration and strength of exposure were created to be used in the Japanese epidemiological study on mobile phone use and the risk of gliomas and meningiomas.
Keywords SAR characterization . Mobile phones . Epidemiological study . Brain tumors . RF exposure . Cancer risk
Evaluation of the SAR induced in a multilayer biological structure and comparison with SAR in homogeneous tissues
Aline Pradier1, Abdelhamid Hadjem1, David Lautru2, Azeddine Gati1, Man-Faï Wong1, Victor Fouad Hanna2, Joe Wiart1
1 France Télécom, Division R&D, RESA/FACE, 38-40, rue Général Leclerc, 92794 Issy Les Moulineaux cedex 9, France
2 Université Pierre et Marie Curie, LISIF, BC 252, 4 place Jussieu, 75252 Paris cedex 05, France
Abstract Wireless systems usage has evolved, for instance, with the recent increase in the use of a hands-free kit, the mobile phone is used more and more in a body-worn position. Therefore, to check the compliance to the international limits, new methods have to be developed. In this study, we analyze the relevance of using the equivalent head liquid for the biological structure of organs that are different from that of the head. This paper compares the Specific Absorption Rate (SAR) values assessed using simulations in a flat phantom filled with the liquid used to test the compliance of mobile phone close to the head to those values obtained using a multilayer model representing the tissues of the trunk. The multilayer structures are derived from the anatomical analysis of the visible human model and corresponding to reasonable positions of a handset in a body-worn configuration. The employed sources are half-wavelength dipoles placed at different distances from those structures and operating at frequencies between 300 MHz and 6 GHz.
Keywords Body worn . Compliance testing . Dosimetry . Electromagnetic exposure . Specific Absorption Rate (SAR)
Personal RF exposimetry in urban area
G. Thuróczy, F. Molnár, G. Jánossy, N. Nagy, G. Kubinyi, J. Bakos, J. Szabó
Department of Non-Ionizing Radiation, National Research Institute for Radiobiology and Radiohygiene, Pf. 101, Budapest 1775, Hungary
Abstract The purpose of the current study was to evaluate the usefulness of a radiofrequency (RF) personal exposimeter (dosimeter) for assessing individual RF exposure in an urban environment. Measurements taken by RF personal dosimeter were also compared to preliminary site measurements taken around mobile base stations. The results from personal exposure showed that one third of the participants spent 40-70% of 24 h recording time above the detection limits (0.05 V/m), and half of subjects spent less than 10%. The highest exposure was detected during the traveling period and the lowest in bed at home. Based on our results, we concluded that site measurements cannot be used to accurately determine personal exposure. We also concluded that duration of time exposed to RF levels above the detection limit of the personal dosimeter is a useful exposure metric to compare and contrast individual RF exposure of study subjects.
Keywords Radiofrequency radiation . Public exposure . Personal exposimetry . Urban area
The Italian national electromagnetic field monitoring network
Francesco Troisi1, Marina Boumis2, Paolo Grazioso3
1 Ministero delle Comunicazioni, Viale America 201, 00144 Roma, Italy
2 Fondazione Ugo Bordoni, Via Baldassarre Castiglione 59, 00142 Roma, Italy
3 Fondazione Ugo Bordoni, Villa Griffone, 40037 Pontecchio Marconi (BO), Italy
Abstract The paper describes the Italian national electromagnetic field monitoring network that the Italian Ministry of Communications established with the technical support of Fondazione Ugo Bordoni and in collaboration with the local Environmental Protection Agencies of all Italian regions.
Keywords Electromagnetic field exposure . Italian Ministry of Communications . Radio frequency
Non-ionizing electromagnetic radiation monitoring in Greece
Antonis Gotsis, Nikolaos Papanikolaou, Dimitris Komnakos, Aamemnon Yalofas, Philip Constantinou
Mobile Radio-Communications Laboratory, School of Electrical and Computer Engineering, National Technical University of Athens, 9 Heroon Polytechneiou Street, Athens, Greece
Abstract The design, development, and operation of a network for the monitoring of the non-ionizing electromagnetic radiation in Greece is presented in this paper. Two independent sub-networks, called “Hermes” and “pedion24” have been operating since November 2002 in many areas, and more than 4,000,000 electric field strength measurements have been conducted to date. The measurement results indicate that the non-ionizing electromagnetic radiation levels are several times below the European Commission Recommendation 1999/519/EC and the Hellenic Republic Law no. 3431 reference levels.
Keywords Electromagnetic radiation . Radiation monitoring . Electric field measurement . Public safety
Occupational exposure to RF fields from base station antennas on rooftops
Tommi Alanko, Maila Hietanen, Patrick von Nandelstadh
Finnish Institute of Occupational Health, New Technologies and Risks, Topeliuksenkatu 41 a A, 00250 Helsinki, Finland
Abstract At specific situations, workers need to approach very close to the transmitting base station antennas. In this study, occupational exposure to RF fields from base station antennas was assessed at several rooftops. The measurements were carried out by mapping the power densities around the antennas. The results were compared with the ICNIRP guidelines. The results indicate that the reference levels for workers and the general public may be exceeded in front of the transmitting antenna at distances up to 1 and 2 m, respectively.
Keywords Base station . Occupational exposure . RF fields . Mobile phone antenna