A novel structure of a near-field communication (NFC) loop antenna for mobile phones with a metal back case is proposed. The proposed structure of the metal back case itself can operate as an NFC loop antenna through the design of a simple single turn loop antenna on the top portion of the metal back case, so that the simple structure of the proposed NFC loop antenna can reduce the overall thickness of the NFC antenna for slim mobile phones. Since a sintered ferrite sheet with generally higher relative permeability (μr ≈ 200) must be used to reduce the performance deterioration of the conventional NFC loop antennas due to the eddy current in the battery pack of a mobile handset, the cost of these conventional NFC antennas is high, and they are considerably fragile. In this paper, the proposed NFC antenna is designed without the ferrite sheet and in the optimal location to ensure minimum interference from the adjacent metallic components.
2. Want, R., "Near field communication," IEEE Pervasive Comput., Vol. 10, No. 3, 4-7, 2011.
3. Fischer, J., "NFC in cell phones: The new paradigm for an interactive world [Near-Field Communications]," IEEE Comm. Mag., Vol. 47, No. 6, 22-28, 2009.
4. Finkenzeller, K., RFID Handbook: Radio-Frequency Identification Fundamentals and Applications, Wiley, London (UK), 2003.
5. Pyykkonen, M., et al., "Designing tangible user interfaces for NFC phone," Advances in Human-Computer Interaction, 1-6, 2012.
6. Ortego, I., et al., "Inkjet printed planar coil antenna analysis for NFC technology applications," Int. J. Antennas Propag., 1-6, 2012.
7. Eun, H., H. Lee, and H. Oh, "Conditional privacy preserving security protocol for NFC applications," IEEE Trans. Consum. Electron., Vol. 59, No. 1, 153-160, 2013.
8. Lee, B., B. Kim, F. J. Harackiewicz, B. Mun, and H. Lee, "NFC antenna design for low permeability ferromagnetic material," IEEE Antennas Wirel Propag. Lett., Vol. 13, 59-62, 2014.
9. Lee, B., B. Kimand, and S. Yang, "Enhanced loop structure of NFC antenna formobile handset applications," Int. J. Antennas Propag., 1-6, 2014.
10. Wong, K. L. and C. H. Chang, "WLAN chip antenna mountable above the system ground plane of a mobile device," IEEE Trans. Antennas Propag., Vol. 53, No. 11, 3496-3499, 2005.
11. Wong, K. L. and C. I. Lin, "Internal GSM/DCS antenna backed by a step-shaped ground plane for a PDA phone," IEEE Trans. Antennas Propag., Vol. 54, No. 8, 2408-2410, 2006.
12. Su, S., "Two-patch-PIFA system with comparable polarization radiation for tablet-computer applications with complete, metal back cover," Microw. Opt. Technol. Lett., Vol. 55, No. 12, 2815-2821, 2013.
13. Anguera, J., et al., "Multiband handset antenna with a parallel excitation of PIFA and slot radiators," IEEE Trans. Antennas Propag., Vol. 58, No. 2, 348-356, 2009.
14. Ahn, J. H., Y. J. Kim, and D. H. Kim, "Mobile terminal having metal case and antenna structure,", U.S. Patent No. 8,054,231, Nov. 8, 2011.
15. Kato, N., et al., "Antenna apparatus,", U.S. Patent No. 0,900,619, Apr. 7, 2015.
16. Nakano, S., "Antenna apparatus and communication terminal,", U.S. Patent No. 8,922,438, Dec. 30, 2014.
17. NXP Semiconductors, "AN190810: PN544 C2 antenna design guide," Application Note, Rev. 1.0, Apr. 2010.
18. EMVco, "EMV contactless specification for payment systems: Book D," EMV Contactless Communication Protocol Specification, Rev. 2.2, Jun. 2012.