This paper presents electromagnetic energy absorption in the homogeneous and layered human body models due to body-worn UWB antennas, at frequencies of 3, 6 and 8 GHz. Typical small planar UWB antennas are used in this study: printed UWB disc monopole and UWB slot antenna. Distances of 2, 5 and 10mm (reactive near-field region) between antennas and human body were chosen, approximating realistic scenarios of operation in Wireless Body Area Networks. To approximate different parts of the human body, or body variations among different users, we compare results obtained for the planar homogeneous (muscle) model with those for three-layer body models (skin, fat and muscle), with different thicknesses of the skin (0.5- 2mm) and fat (1-9mm) tissue. For these body models we investigate the electromagnetic energy absorption mechanism by examining the peak 1-g SAR and peak SAR (without mass averaging). Based on our results we present and discuss new finding concerning the general electromagnetic energy absorption mechanism in human tissues under reactive near-fields exposure conditions.
1. Stuchly, M., "Electromagnetic fields and health," IEEE Potentials, Vol. 12, No. 4, 34-39, 1993. doi:10.1109/45.283813
2. Rosen, A., M. A. Stuchly, and A. Vander Vorst, "Applications of RF/microwaves in medicine," IEEE Transactions on Microwave Theory and Techniques, Vol. 50, No. 3, 963-974, 2002. doi:10.1109/22.989979
3. Chatterjee, I., M. J. Hagmann, and O. P. Gandhi, "Electromagnetic absorption in a multilayered slab model of tissue under nearfield exposure conditions," Bioelectromagnetics, Vol. 1, 379-388, 1980. doi:10.1002/bem.2250010404
4. Chatterjee, I., M. J. Hagmann, and O. P. Gandhi, "Plane-wave spectrum approach for the calculation of electromagnetic absorption under near-field exposure conditions," Bioelectromagnetics, Vol. 1, 363-377, 1980. doi:10.1002/bem.2250010403
5. Kuster, N., "Multiple multipole method for simulating EM problems involving biological studies," IEEE Transactions on Biomedical Engineering, Vol. 40, No. 7, 611-620, 1993. doi:10.1109/10.237691
6. Kuster, N. and Q. Balzano, "Energy absorption mechanism by biological bodies in the near field of dipole antennas above 300 MHz," IEEE Transactions on Vehicular Technology, Vol. 41, No. 2, 17-23, 1992. doi:10.1109/25.120141
7. Meier, K., V. Hombach, R. Kastle, R. Y.-S. Tay, and N. Kuster, "The dependence of electromagnetic energy absorption upon human-head modeling at 1800 MHz," IEEE Transactions on Microwave Theory and Techniques, Vol. 45, No. 11, 2058-2062, 1997. doi:10.1109/22.644237
8. Lazzi, G., C. M. Furse, and G. P. Ghandi, FDTD computation of electromagnetic absorption in the human head from mobile telephones, Proc. of the 18th Annual Technical Meeting of the Bioelectromagnetics Society-BEMS, 1996.
9. Christ, A. and N. Kuster, "Differences in RF energy absorption in the heads of adults and children," Bioelectromagnetics, No. 9, 2005.
10. Pitchers, S. M. and D.A. Eves, "A protocol for body centric networks," IEE Eurowearable, 4-5, 2003.
11. Zasowski, T., F. Althaus, M. Stger, A. Wittneben, and G. Trster, UWB for noninvasive wireless body area networks: Channel measurements and results, IEEE Conference on Ultra Wideband Systems and Technologies, No. 11, 2003.
12. Hao, Y., A. Alomainy, P. S. Hall, Y. I. Nechayev, C. G. Parini, and C. C. Constantinou, Antennas and propagation for body centric wireless communications, 2005. IEEE/ACES International Conference on Wireless Communications and Applied Computational Electromagnetics, 3-7, 2005.
13. Chen, Z. N., X. H. Wu, H. F. Li, N. Yang, and M. Y. W. Chia, "Considerations for source pulses and antennas in UWB radio systems," IEEE Transactions on Antennas and Propagation, Vol. 52, No. 7, 1739-1748, 2004. doi:10.1109/TAP.2004.831405
14. Klemm, M., I. Z. Kovacs, G. F. Pedersen, and G. Troster, "Novel small-size directional antenna for UWB WBAN/WPAN applications," IEEE Transactions on Antennas and Propagation, No. 12, 2005.
15. Klemm, M. and G. Troster, "Integration of electrically small UWB antennas for body-worn sensor applications," IEE Wideband and Multi-band Antennas and Arrays, 141-146, 2005. doi:10.1049/ic:20050302
16. Chen, Z. N., A. Cai, T. See, and M. Chia, Small planar UWB antennas in proximity of human head, 2005 IEEE International Conference on Ultra-Wideband (ICU 2005), 5-8, 2005.
17. Cai, A., T. See, and Z. N. Chen, "Study of human head effects on UWB antenna," 2005 IEEE International Workshop on Antenna Technology: Small Antennas and Novel Metamaterials (IWAT 2005), 7-9, 2005.
18. Alomainy, A., Y. Hao, C. G. Parini, and P. S. Hall, "Comparison between two different antennas for UWB onbody propagation measurements," IEEE Antennas and Wireless Propagation Letters, Vol. 4, 31-34, 2005. doi:10.1109/LAWP.2005.844143
19. Klemm, M., I. Locher, and G. Troster, A novel circularly polarized textile antenna for wearable applications, The 34rd European Microwave Conference (EuMC), 11-14, 2004.
20. Bharatula, N. B., M. Stger, P. Lukowicz, and G. Trster, Empirical study of design choices in multisensor context recognition system, IFAWC 2005: Proceedings of the 2nd International Forum on Applied Wearable Computing, 17-18, 2005.
21. Kang, G. and O. P. Gandhi, "Effect of dielectric properties on the peak 1-and 10-g SAR for 802.11 a/b/g frequencies 2.45 and 5.15 to 5.85 GHz," IEEE Transactions on Electromagnetic Compatibility, Vol. 46, No. 5, 268-274, 2004. doi:10.1109/TEMC.2004.826875
22. Onishi, T. and S. Uebayashi, Influence of phantom shell on SAR measurement in 3-6 GHz frequency range, 2004 International Symposium on Electromagnetic Compatibility, 3-6, 2004.
23. IT'IS Foundation, Research projects â€” bio-electromagnetics and electromagnetic compatibility, http://www.iis.ee.ethz.ch/portrait/review/2004/BioEM04.pdf.
24. Christ, A., A. Klingenboeck, and N. Kuster, Energy absorption in layered biological tissue and its consequence on the compliancetesting of body-mounted wireless devices, Progress in Electromagnetics Research Symposium 2005, 23-26, 2005.
25. Kiveks, O., T. Lehtiniemi, and P. Vainikainen, "On the general energy-absorption mechanism in the human tissue," Microwave and Optical Technology Letters, Vol. 43, No. 9, 195-201, 2004. doi:10.1002/mop.20418
26. Klemm, M. and G. Troster, "Characterization of small planar antennas for UWB mobile terminals," Wireless Communications and Mobile Computing, Vol. 5, No. 8, 501-597, 2005.
27. Qing, X., M. Y. W. Chia, and X. Wu, Wide-slot antenna for UWB applications, IEEE Antennas and Propagation Symposium, Vol. 1, 22-27, 2003.
28. Behdad, N., "A wideband multiresonant single-element slot antenna," Antennas and Wireless Propagation Letters, Vol. 3, 5-8, 2004. doi:10.1109/LAWP.2004.825093
30. Balanis, C. A., Antenna Theory: Analysis and Design, 2nd Ed. Ed., Wiley, 1996.
31. Caputa, K., M. Okoniewski, and M. A. Stuchly, "An algorithm for computations of the power deposition in human tissue," IEEE Antennas and Propagation Magazine, Vol. 41, No. 8, 102-107, 1999. doi:10.1109/74.789742
32. IEEE Standard for Safety Levels With Respect to Human Exposure to Radiofrequency Electromagnetic Fields, 3 kHz to 300 GHz, IEEE Std. C95.1, 2002.