volume | PIER Journals

Abstract

Handset antennas strongly interact with the human body. When a user holds a handset during a phone call, the proximity of the human head considerably affects the antenna performance and eventually the quality of the wireless connection. Consequently, the assessment of the antenna parameters regarding free-space conditions is not enough to fully characterize the performance of handset antennas and a further analysis taking into account human head interaction is required. In this sense, this paper presents a study that deals with the human head interaction concerning two aspects: functional and biological. The first one analyzes the effect of the human head over the main antenna parameters (reflection coefficient, efficiency, and radiation pattern) whereas the second one evaluates the impact of the antenna over the human head in terms of Specific Absorption Rate (SAR). Four representative prototypes of radiating structures are measured in both conditions in order to compare their performance: a dual-band Planar Inverted F Antenna (PIFA), a hexa-band PIFA with a slotted ground plane, a set of coupled monopoles, and a new architecture referred as compact radiating system based on the excitation of the ground plane through a set of non-resonant ground plane boosters. A figure of merit that relates the antenna efficiency with the SAR values is proposed for comparison purposes. The results demonstrate that losses caused by the human head power absorption can be minimized if the antennas are placed in the edge located at a higher distance from the human cheek. Furthermore, the study reveals the robustness of the compact radiating system taking into account the human presence. This fact reinforces its position as an alternative solution to current handset antennas, capable of providing penta-band operation (GSM850/900, DCS, PCS, and UMTS) through ground plane boosters featured by their reduced volume of only 250 mm³.

1. Frost, F. and Sullivan, Antennas Systems, Washington, USA, 2006.

2. Geissier, M., D. Heberling, and I. Wolff, "Bandwidth and radiating properties of internal handset antennas," IEEE Antennas and Propagation Society International Symposium, Vol. 4, 2246-2249, July 2000.

3. Planar Antennas for Wireless Communications, John Wiley & Sons, New York, 2003.

4. Puente, C., J. Anguera, J. Soler, and A. Condes, "Coupled multi-band antennas," Patent Appl. WO2004/025778, Sep. September 10, 2002.

5. Lin, C. and K. L. Wong, "Printed monopole slot antenna for internal multiband mobile phone antenna," IEEE Transactions on Antennas and Propagation, Vol. 55, No. 12, 3690-3697, December 2007.
doi:10.1109/TAP.2007.910345

6. Risco, S., J. Anguera, A. Andújar, A. Pérez, and C. Puente, "Coupled monopole antenna design for multiband handset devices," Microwave and Optical Technology Letters, Vol. 52, No. 2, 359-364, February 2010.
doi:10.1002/mop.24893

7. Wu, C. and K. Wong, "Hexa-band internal printed slot antenna for mobile phone application," Microwave and Optical Technology Letters, Vol. 50, No. 1, 35-38, January 2008.
doi:10.1002/mop.22981

8. Anguera, J., I. Sanz, J. Mumbrú, and C. Puente, "Multi-band handset antenna with a parallel excitation of PIFA and slot radiators," IEEE Transactions on Antennas and Propagation, Vol. 58, No. 2, 348-356, February 2010.
doi:10.1109/TAP.2009.2038183

9. Anguera, J., I. Sanz, A. Sanz, A. Condes, D. Gala, C. Puente, and J. Soler, "Enhancing the performance of handset antennas by means of groundplane design," IEEE International Workshop on Antenna Technology: Small Antennas and Novel Metamaterials (iWAT), March 2006.

10. Anguera, J., A. Cabedo, C. Picher, I. Sanz, M. Ribó, and C. Puente, "Multiband handset antennas by means of groundplane modification," IEEE Antennas and Propagation Society International Symposium, June 2007.
doi:10.1109/TAP.2009.2038183

11. Picher, C., J. Anguera, A. Cabedo, C. Puente, and S. Kahng, "Multiband handset antenna using slots on the ground plane: Considerations to facilitate the integration of the feeding transmission line," Progress In Electromagnetics Research C, Vol. 7, 95-109, 2009.
doi:10.2528/PIERC09030605

12. Cabedo, A., J. Anguera, C. Picher, M. Ribó, and C. Puente, "Multi-band handset antenna combining a PIFA, slots, and ground plane modes," IEEE Transactions on Antennas and Propagation, Vol. 57, No. 9, 2526-2533, September 2009.
doi:10.1109/TAP.2009.2027039

13. Quintero, R. and C. Puente, "Multilevel and space-filling ground planes for miniature and multiband antennas," Patent Appl. WO2003/023900, September 13, 2001.

14. Anguera, J. and C. Puente, "Shaped ground plane for radio apparatus," Patent Appl. WO2006/070017, December 29, 2005.

15. Cabedo-Fabrés, M., E. Antonino-Daviu, A. Valero-Nogueira, and M. F. Bataller, "The theory of characteristic modes revisited: A contribution to the design of antennas for modern applications," IEEE Antennas and Propagation Magazine, Vol. 49, No. 5, 52-68, October 2007.
doi:10.1109/MAP.2007.4395295

16. Schroeder, W. L., C. T. Famdie, and K. Solbach, "Utilization and tuning of the chassis modes of a handheld terminal for the design of multiband radiation characteristics," IEEE Transactions on Antennas and Propagation, Vol. 50, No. 10, 1433-1444, October 2002.

17. Puente, C. and J. Anguera, "Handset with electromagnetic bra," Patent Appl. WO2005/083833, February 28, 2005.

18. Ozden, S., B. K. Nielsen, C. H. Jorgensen, J. Villanen, C. Icheln, and P. Vainikainen, "Quad-band coupling element antenna structure," U.S. Patent 7,274,340, September 25, 2007.

19. Anguera, J., I. Sanz, C. Puente, and J. Mumbrú, "Wireless device including a multiband antenna system," Patent Appl. WO2008/119699, March 26, 2008.

20. Anguera, J., A. Andújar, C. Puente, and J. Mumbrú, "Antennaless wireless device," Patent Appl. WO2010/015365, July 31, 2009.

21. Andújar, A., C. Puente, and J. Mumbrú, "Antennaless wireless device capable of operation in multiple frequency regions," Patent Appl. WO2010/015364, July 31, 2009.

22. Andújar, A., J. Anguera, and C. Puente, "Ground plane boosters as a compact antenna technology for wireless handheld devices," IEEE Transactions on Antennas and Propagation, Vol. 59, No. 5, 1668-1677, May 2011.
doi:10.1109/TAP.2011.2122299

23. Anguera, J., A. Camps, A. Andújar, and C. Puente, "Enhancing the robustness of handset antennas to finger loading effects," Electronics Letters, Vol. 45, No. 15, 770-771, July 2009.
doi:10.1049/el.2009.0887

24. Jung, J. M., S. Kim, K. Kong, J. Lee, and B. Lee, "Designing ground plane to reduce hand effects on mobile handsets," IEEE Antennas and Propagation Society International Symposium, 1040-1043, June 2007.

25. Su, C., C. Wu, and K. Wong, "User's hand effects on EMC internal GSM/DCS mobile phone antenna," IEEE Antennas and Propagation Society International Symposium, 2097-2100, July 2006.

26. Toftgard, J., S. N. Hornsleth, and J. B. Andersen, "Effects on portable antennas of the presence of a person," IEEE Transaction on Antennas and Propagation, Vol. 41, No. 6, 739-746, 1993.
doi:10.1109/8.250451

27. Okoniewski, M. and M. A. Stuchly, "A study of the handset antenna and human body interaction," IEEE Transactions on Microwave Theory and Techniques, Vol. 44, No. 10, 1855-1864, October 1996.
doi:10.1109/22.539944

28. Kildal, P. S. and C. Carlsson, "Comparison between head losses of 20 phones with external and built-in antennas measured in reverberation chamber," IEEE Antennas and Propagation Society International Symposium, Vol. 1, 436-439, August 2002.

29. Boyle, K. R., Y. Yuan, and L. P. Ligthart, "Analysis of mobile phone antenna impedance variations with user proximity," IEEE Transaction on Antennas and Propagation, Vol. 55, No. 2, 364-372, February 2007.
doi:10.1109/TAP.2006.889834

30. Huang, T. and K. R. Boyle, "User interaction studies on handset antennas," European Conference on Antennas and Propagation --- EuCAP, 2007.

31. Lu, D., D. Fisk, and A. Wang, "A mobile antenna design for optimal performance in human head and hand configuration," IEEE Antennas and Propagation Society International Symposium, 1048-1048, June 2007.

32. 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

33. Schiavoni, A., P. Bertotto, G. Richiardi, and P. Bielli, "SAR generated by commercial cellular phones --- Phone modeling, head modeling, and measurements," IEEE Transactions on Microwave Theory and Techniques, Vol. 18, No. 11, 2064-2071, November 2000.

34. Bernardi, P., M. Cavagnaro, S. Pisa, and E. Piuzzi, "Power absorption and temperature elevations induced in the human head by a dual-band monopole-helix antenna phone," IEEE Transactions on Microwave Theory and Techniques, Vol. 49, No. 12, 2539-2546, December 2001.
doi:10.1109/22.971647

35. Hirata, A. and T. Shiozawa, "Correlation of maximum temperature increase and peak SAR in the human head due to handset antennas," IEEE Transactions on Microwave Theory and Techniques, Vol. 51, No. 7, 1834-1841, July 2003.
doi:10.1109/TMTT.2003.814314

36. Khodabakhshi, H. and A. Cheldavi, "Human head interaction with a PIFA in cellular mobile communication," European Conference on Antennas and Propagation --- EuCAP, 2010.

37. Risco, S., J. Anguera, A. Andjar, C. Picher, and J. Pajares, "Comparison of a monopole and a PIFA handset antenna in the presence of the human head," Microwave and Optical Technology Letters, Vol. 54, No. 2, 454-459, Feb. 2012.
doi:10.1002/mop.26565

38., July 2001.
doi:10.1002/mop.26565

39. Martínez, M., O. Letschke, M. Geissler, D. Heberling, A. M. Martínez, and D. Sánchez, "Integrated planar multiband antennas for personal communication handsets," IEEE Transactions on Antennas and Propagation, Vol. 54, No. 2, 384-391, February 2006.
doi:10.1109/TAP.2005.863402

40. Kim, B., S. Park, Y. Yoon, J. Oh, K. Lee, and G. Koo, "Hexaband planar inverted-f antenna with novel feed structure for wireless terminals," IEEE Antennas and Wireless Propagation Letters, Vol. 6, 66-69, 2007.
doi:10.1109/LAWP.2007.893066

41. Hsieh, H., Y. Lee, K. Tiong, and J. Sun, "Design of a multiband antenna for mobile handset operations," IEEE Antennas and Wireless Propagation Letters, Vol. 8, 200-203, 2009.
doi:10.1109/LAWP.2008.2011655

42. Li, Z. and Y. Rahmat-Samii, "Optimization of pifa-ifa combination in handset antenna designs," IEEE Transactions on Antennas and Propagation, Vol. 53, No. 5, 1770-1778, May 2005.
doi:10.1109/TAP.2005.846807

Dr. Aurora Andujar

Dr. Jaume Anguera

Ms. Cristina Picher

Dr. Carles Puente