volume | PIER Journals

Abstract

This study investigated the relationship between temperature elevation and spatial-average SAR (specific absorption rate) in a head model of a Japanese male due to a dipole antenna. The frequencies considered are in the range between 800MHz and 3 GHz, which are used in wireless communications. Our attention focuses on the average mass of SAR which maximizes the correlation with local temperature elevation. Computational results suggested that an appropriate averaging mass of SAR did not exist over wide frequencies, which was attributed to the frequency-dependent penetration depth of electromagnetic waves. For most cases considered in this study the SAR averaging over 10 g was better than that for 1-g from the standpoint of correlating the temperature elevation. The dominant factor influencing this averaging mass is the thermal diffusion length which largely depends on the blood perfusion rate. Additionally, the heat evolved in the pinna played an important role in the correlation between spatialaverage SAR and temperature elevation.

1. ICNIRP, ``Guidelines for limiting exposure to time-varying electric, magnetic, "Guidelines for limiting exposure to time-varying electric, magnetic and electromagnetic fields (up to 300 GHz)," Health Phys., Vol. 74, 494-522, 1998.

2. IEEE, C95.1 IEEE standard for safety levels with respect to human exposure to radio frequency electromagnetic fields, 3 KHz to 300 GHz, IEEE, New York, 2005.

3. Kang, X. K., L. W. Li, M. S. Leong, and P. S. Kooi, "A method of moments study of SAR inside spheroidal human head and current distribution along handset wire antennas," J. Electromagnetic Waves and Appl., Vol. 15, No. 61-75, 61-75, 2001.
doi:10.1163/156939301X00643

4. Kouveliotis, N. K., P. J. Papakanellos, E. D. Nanou, N. I. Sakka, V. S. G. Tsiafkis, and C. N. Capsalis, "Correlation between SAR, SWR and distance of mobile terminal antenna in front of a human phantom: Theoretical and experimental validation," J. Electromagnetic Waves and Appl., Vol. 17, No. 1561-1581, 1561-1581, 2003.
doi:10.1163/156939303772681415

5. Pino, A. G., M. Arias, M. G. Sanchez, I. Cuinas, and A. A. Alonso, "Determination of safety volumes for medium-frequency emissions under standard limits of human exposure," J. Electromagnetic Waves and Appl., Vol. 17, No. 11, 1605-1611, 2003.
doi:10.1163/156939303772681460

6. Yoshida, K., A. Hirata, Z. Kawasaki, and T. Shiozawa, "Human head modeling for handset antenna design at 5 GHz band," J. Electromagnetic Waves and Appl., Vol. 19, No. 3, 401-411, 2005.
doi:10.1163/1569393054139679

7. Kiminami, K., A. Hirata, Y. Horii, and T. Shiozawa, "A study on human body modeling for the mobile antenna design at 400MHz band," J. Electromagnetic Waves and Appl., Vol. 19, No. 5, 671-687, 2005.
doi:10.1163/1569393053305080

8. Kuo, L. C., Y. C. Kan, and H. R. Chuang, "Analysis of a 900/1800-MHz dual-band gap loop antenna on a handset with proximate head and hand model," J. Electromagnetic Waves and Appl., Vol. 21, No. 1, 107-122, 2007.
doi:10.1163/156939307779391722

9. Ebrahimi-Ganjeh, M. A. and A. R. Attari, "Interaction of dual band helical and PIFA handset antennas with human head and hand," Progress In Electromagnetics Research, Vol. 77, 225-242, 2007.
doi:10.2528/PIER07081804

10. Liu, Y., Z. Liang, and Z. Q. Yang, "Computation of electromagnetic dosimetry for human body using parallel FDTD algorithm combined with interpolation technique," Progress In Electromagnetics Research, Vol. 82, 95-107, 2008.

11. Adair, E. R., B. W. Adams, and G. M. Akel, "Minimal changes in hypothalamic temperature accompanymicrowave-induced alteration of thermoregulatory behavior," Bioelectromagnetics, Vol. 5, 13-30, 1984.
doi:10.1002/bem.2250050103

12. Guyton, A. C. and J. E. Hall, Textbook of Medical Physiology, W. B. Saunders, Philadelphia, PA, 1996.

13. Hardy, J. D. and H. G. Wolff, and Goodell, Pain Sensation and Reactions, Chap. IV and X, Williams & Wilkis, Baltimore, MD, 1952.

14. Wang, J. and O. Fujiwara, "FDTD computation of temperature rise in the human head for portable telephones," IEEE Trans. Microwave Theory & Tech., Vol. 47, 1528-1534, 1999.
doi:10.1109/22.780405

15. Van Leeuwen, G. M. J., J. J. W. Lagendijk, B. J. A. M. Van Leersum, A. P. M. Zwamborn, S. N. Hornsleth, and A. N. T. Kotte, "Calculation of change in brain temperatures due to exposure to a mobile phone," Phys. Med. Biol., Vol. 44, 2367-2379, 1999.
doi:10.1088/0031-9155/44/10/301

16. Bernardi, P., M. Cavagnaro, S. Pisa, and E. Piuzzi, "Specific absorption rate and temperature increases in the head of a cellularphone user," IEEE Trans. Microwave Theory & Tech., Vol. 48, 1118-1126, 2000.
doi:10.1109/22.848494

17. Wainwright, P., "Thermal effects of radiation from cellular telephones," Phys. Med. Biol., Vol. 45, 2363-2372, 2000.
doi:10.1088/0031-9155/45/8/321

18. Hirata, A. and T. Shiozawa, "Correlation ofmaximum temperature increase and peak SAR in the human head due to handset antennas," IEEE Trans. Microw. Theory Tech., Vol. 51, No. 7, 1834-1841, 2003.
doi:10.1109/TMTT.2003.814314

19. Hirata, A., M. Morita, and T. Shiozawa, "Temperature increase in the human head for dipole antenna at microwave frequencies," IEEE Trans. Electromagnetic Compat., Vol. 45, No. 1, 109-116, 2003.
doi:10.1109/TEMC.2002.808045

20. Ibrahiem, A., C. Dale, W. Tabbara, and J. Wiart, "Analysis of the temperature increase linked to the power induced by RF source," Progress In Electromagnetics Research, Vol. 52, 23-46, 2005.
doi:10.2528/PIER04062501

21. Hirata, A., M. Fujimoto, T. Asano, J. Wang, O. Fujiwara, and T. Shiozawa, "Correlation between maximum temperature increase and peak SAR with different average schemes and masses," IEEE Trans. Electromagnetic Compat., Vol. 48, 569-578, 2006.
doi:10.1109/TEMC.2006.877784

22. Burkhart, M. and N. Kuster, "Appropriate modeling of the ear for compliance testing of handheld MTE with SAR safety limits at 900/1800 MHz," IEEE Trans. Microwave Theory Tech., Vol. 48, 1927-1934, 2000.
doi:10.1109/22.883873

23. Bit-Babik, G.A. Faraone, C. K. Chou, A. Radmadze, and R. Zaridze, "Correlation between locally averaged SAR distribution and related temperature rise in human body exposed to RF field," Proc. BEMS 2007, 2-5, 2007.

24. Hirata, A.K. Shirai, and O. Fujiwara, "Relationship between temperature elevation and spatial average SAR in Japanese human head model due to dipole antenna," IEEE International Symposium on Electromagnetic Compatibility, 2 2007.

25. Wang, J. and O. Fujiwara, "Dosimetric evaluation of human head for portable telephones," Electron. Commun. Japan, Vol. 85, No. 7, 12-22, 2002.
doi:10.1002/ecja.1107

26. Taflove, A. and S. Hagness, Computational Electrodynamics: The Finite-Difference Time-Domain Method, 2nd edition, Artech House, Norwood, MA, 2003.

27. Gabriel, C., "Compilation of the dielectric properties of body tissues at RF and microwave frequencies," Final Tech. Rep. Occupational and Environmental Health Directorate, 1996-0037, 1996.

28. Volakis, J. L., K. Caputa, M. Okoniewski, and M. A. Stuchly, "An algorithm for computations of the power deposition in human tissue," IEEE Antenna Propagat. Mag., Vol. 41, No. 4, 102-107, 1999.
doi:10.1109/74.789742

29. Yu, W., D. H. Werner, and R. Mittra, "Finite Difference Time Domain (FDTD) analysis of an artificially-synthesized absorbing medium," J. Electromagnetic Waves and Appl., Vol. 15, No. 8, 1005-1026, 2001.
doi:10.1163/156939301X00364

30. Watanabe, S. and M. Taki, "An improved FDTD model for the feeding gap of a thin-wire antenna," IEEE Microwave & Guided Wave Letts., Vol. 8, 152-154, 1999.
doi:10.1109/75.663515

31. IEEE C95.3, IEEE Recommended Practice for Measurements and Computations of Radio Frequency, IEEE Recommended Practice for Measurements and Computations of Radio Frequency, IEEE, New York, 2002.

32. Pennes, H. H., "Analysis of tissue and arterial blood temperature in resting forearm," J. Appl. Physiol., Vol. 1, 93-122, 1948.

33. Duck, F. A., Physical Properties of Tissue, Academic, New York, 1990.

34. Fiala, D., K. J. Lomas, and M. Stohrer, "A computer model of human thermoregulation for a wide range of environmental conditions: The passive system," J. Appl Physiol., Vol. 87, 1957-1972, 1999.

35. Samaras, T., A. Christ, and N. Kuster, "Effects of geometry discretization aspects on the numerical solution on the bioheat transfer equation with the FDTD technique," Phys. Med. Biol., Vol. 51, 221, 2006.
doi:10.1088/0031-9155/51/11/N02

36. Neufeld, E., N. Chavannes, T. Samaras, and N. Kuster, "Novel conformal technique to reduce staircasing artifacts at material boundaries for FDTD modeling of the bioheat equation," Phys. Med. Biol., Vol. 52, 4371-4381, 2007.
doi:10.1088/0031-9155/52/15/001

37. IEEE C95.1, IEEE Standard for Safety Levels with Respect to Human Exposure to Radio Frequency Electromagnetic Fields, IEEE Standard for Safety Levels with Respect to Human Exposure to Radio Frequency Electromagnetic Fields, 3 KHz to 300 GHz, IEEE, New York, 1991.

38. Gandhi, O. P., G. Lazzi, and C. M. Furse, "Electromagnetic absorption in the human head and neck for mobile telephones at 835 and 1900 MHz," IEEE Trans. Microwave Theory and Tech., Vol. 44, No. 10, 1884-1897, 1996.
doi:10.1109/22.539947

39. Watanabe, S., M. Taki, T. Nojima, and O. Fujiwara, "Characteristics of the SAR distributions in a head exposed to electromagnetic fields radiated by a hand-held portable radio," IEEE Trans. Microwave Theory and Tech., Vol. 44, No. 10, 1874-1883, 1996.
doi:10.1109/22.539946

40. Okoniewski, M. and M. A. Stuchly, "A study of the handset antenna and human body interaction," IEEE Trans. Microwave Theory & Tech., Vol. 44, 1855-1864, 1996.
doi:10.1109/22.539944

Prof. Akimasa Hirata

Dr. Kazuyuki Shirai

Dr. Osamu Fujiwara