Wearable Antennas for Body-Centric Communications: Design and Characterization Aspects
Keywords:
Antenna characterization, antenna design, optimization, radiation efficiency, SAR, wearable antennaAbstract
Wearable antennas exhibit numerous challenges in terms of design and optimization due to the specific environment in which they operate. Therefore, the design of such antennas is a non-trivial task, as multiple constraints have to be satisfied. We present an algorithm for design-and-optimization of flexible wearable antennas with high radiation efficiency and low specific absorption rate, that takes into account the dielectric loading of the human body. It provides a list of feasible antenna designs, not just a single solution, and identifies the optimal wearable antenna design. Numerical examples on the design and optimization of a wearable antenna (based on a dipole structure with a reflector) to demonstrate the validity and efficiency of the proposed algorithm are given. The optimal antenna design shows robust on-body performance and provides a suitable balance between small antenna size (antenna surface is 2214 mm2), high radiation efficiency (57.73%), and low value of the maximum 10 g average SAR (0.112 W/kg) on a homogeneous semisolid phantom. Finally, the optimal antenna design is fabricated. The antenna performance is studied under different conditions: on a homogeneous semisolid phantom, on a liquid phantom, on a three-layer semisolid phantom, on a human arm and in the free space. A good agreement between simulated and measured antenna performance is observed.
Downloads
References
P. Hall and Y. Hao, Antennas and Propagation for Body-Centric Wireless Communications, 2nd ed., Artech House, London, 2012.
Q. H. Abbasi, M. U. Rehman, K. Qaraqe, and A. Alomainy, Advances in Body-Centric Wireless Communication: Applications and State-of-the-Art, IET, London, 2016.
N. F. M. Aun, P. J. Soh, A. A. Al-Hadi, M. F. Jamlos, G. A. E. Vandenbosch, and D. Schreurs, “Revolutionizing wearables for 5G,” IEEE Microwave Magazine, vol. 18, no. 3, pp. 108-124, May 2017.
A. Y. I. Ashyap, Z. Z. Abidin, et al., “Inverted E-shaped wearable textile antenna for medical applications,” IEEE Access, vol. 6, pp. 1-9, June 2018.
K. Ito, N. Haga, M. Takahashi, and K. Saito, “Evaluations of body-centric wireless communication channels in a range from 3 MHz to 3 GHz,” Proceedings of the IEEE, vol. 100, no. 7, pp. 2356- 2363, July 2012.
W. -C. Chen, B. DeLong, R. Vilkhu, and A. Kiourti, “Enabling batteryless wearables and implants,” ACES Journal, vol. 33, no. 10, pp. 1106- 1108, Oct. 2018.
S. Dumanli, L. Sayer, E. Mellios, X. Fafoutis, G. S. Hilton, and I. J. Craddock, “Off-body antenna wireless performance evaluation in a residential environment,” IEEE Trans. on Antennas and Propagt., vol. 65, no. 11, pp. 6076-6084, Nov. 2017.
G. Conway, S. Cotton, and W. Scanlon, “An antennas and propagation approach to improving physical layer performance in wireless body area networks,” IEEE J. on Selected Area in Comm., vol. 27, no. 1, pp. 27-36, Jan. 2009.
A. Pellegrini, A. Brizzi, et al., “Antennas and propagation for body-centric wireless communications at millimeter-wave frequencies: A review,” IEEE Antennas and Propagt. Magazine, vol. 55, no. 4, pp. 262-287, Aug. 2013.
H. Khaleel, Innovation in Wearable and Flexible Antennas, WIT press, Southampton, 2015.
Ł. Januszkiewicz, P. D. Barba, and S. Hausman, “Optimization of wearable microwave antenna with simplified electromagnetic model of the human body,” OpenPhys., vol. 15, pp. 1055-1060, Nov. 2017.
A. Zare and S. Baghaie, “Application of ant colony optimization algorithm to pattern synthesis of uniform circular antenna array,” ACES Journal, vol. 30, no. 8, pp. 810-818, Aug. 2015.
P. Rocca and R. Haupt, “Biologically inspired optimization of antenna arrays,” ACES Journal, vol. 29, no. 12, pp. 1047-1059, Dec. 2014.
K. Fertas, H. Kimouche, M. Challal, H. Aksas, R. Aksas, and A. Azrar, “Design and optimization of a CPW-fed tri-band patch antenna using genetic algorithms,” ACES Journal, vol. 30, no. 7, pp. 754- 759, July 2015.
Z. Li, Y. Erdemli, J. Volakis, and P. Papalambros, “Design optimization of conformal antennas by integrating stochastic algorithms with the hybrid Finite-Element method,” IEEE Trans. on Antennas and Propagt., vol. 50, no. 5, pp. 676-684, May 2012.
D. Prado, J. Álvarez, M. Arrebola, M. Pino, R. Ayestarán, and F. Las-Heras, “Efficient, accurate and scalable reflectarray phase-only synthesis based on the Levenberg-Marquardt algorithm,” ACES Journal, vol. 30, no. 12, pp. 1246-1255, Dec. 2015. [17] X. Travassos, D. Vieira, and A. Lisboa, “Antenna optimization using multiobjective algorithm,” ISRN Communications and Networking, vol. 2012, pp. 1-8, 2012.
P. Nepa and H. Rogier, “Wearable antennas for off-body radio links at VHF and UHF bands: Challenges, the state of the art, and future trends below 1 GHz,” IEEE Antennas and Propagt. Magazine, vol. 57, no. 5, pp. 30-52, Oct. 2015.
N. H. M. Rais, P. J. Soh, F. Malek, S. Ahmad, N. B. M. Hashim, and P. S. Hall, “A review of wearable antenna,” Loughborough Antennas & Propagation Conference, pp. 225-228, Nov. 2009.
B. Gupta, S. Sankaralingam, and S. Dhar, “Development of wearable and implantable antennas in the last decade: A review,” in Proceedings of the 10th Mediterranean Microwave Symposium (MMS '10), pp. 251-267, Aug. 2010.
S. Dhupkariya, V. K. Singh, and A. Shukla, “A review of textile materials for wearable antenna,” J. Microwave Eng. Technol., vol. 1, no. 3, pp. 2349-9001, Oct. 2015.
C. A. Balanis editor, Modern Antenna Handbook, John Wiley & Sons, Inc., Hoboken, 2008.
A. Al-Sehemi, A. Al-Ghamdi, N. Dishovsky, N. Atanasov, and G. Atanasova, “On-body of a compact planar antenna on multilayer polymer composite for body-centric wireless communications,” AEU – International Journal of Electronics and Communications, vol. 82, pp. 20-29, Dec. 2017.
T. Björninen, “Comparison of three body models of different complexities in modelling of equalsized dipole and folded dipole wearable passive UHF RFID tags,” ACES Journal, vol. 33, no. 6, pp. 706-709, June 2018.
EN 62209-2, Human exposure to radio frequency fields from hand-held and body mounted devices – Human models, instrumentation, and procedures - Part 2: Procedure to determine the specific absorption rate (SAR) for wireless communication devices used in close proximity to the human body (frequency range of 30 MHz to 6 GHz), IEC, 2010.
IEEE for Recommended Practice for Determining the Peak Spatial-Average Specific Absorption Rate (SAR) in the Human Head from Wireless Communications Devices: Measurement Techniques, IEEE Standard 1528, 2003.
FCC, SAR measurement requirements for 100 MHz to 6 GHz, Aug. 2015.
L. Chen, C. Ong, C. Neo, V. V. Varadan, and V. K. Varadan, Microwave Electronics: Measurement and Materials Characterization, 1st ed., John Wiley & Sons, Ltd., 2004.
