Broadband compact substrate-independent textile wearable antenna for simultaneous near- and far-field wireless power transmission

Wagih, M. , Komolafe, A., Weddell, A. S. and Beeby, S. (2022) Broadband compact substrate-independent textile wearable antenna for simultaneous near- and far-field wireless power transmission. IEEE Open Journal of Antennas and Propagation, 3, pp. 398-411. (doi: 10.1109/OJAP.2022.3167089)

Abstract

Despite an increasing interest in wearable wireless power transmission (WPT), until now, wearable antennas have been unable to simultaneously harvest from near-field resonant and far-field radiative WPT. Here, a dual-port antenna is proposed, integrating an inductive coil with a broadband monopole for near- and far-field wearable WPT. The coil acts simultaneously as a High Frequency (HF) near-field power receiver and an Ultra-High Frequency (UHF) resonator, enabling the miniaturization of the enclosed broadband monopole, both fabricated using all-textile conductors. On-body, the antenna maintains a 10 dB return loss over a measured 135% fractional bandwidth while maintaining compactness ( 0.312×0.312λ2 ). The antenna is substrate-independent and is demonstrated on two textile substrates with different dielectric properties and thicknesses. In far-field mode, the rectenna maintains over 40% efficiency from sub-1 μW /cm2 power densities. In the near-field, a WPT efficiency up to 80% can be achieved. The simulated Specific Absorption Rate (SAR) shows up to 40 and 20 dBm power reception for HF and UHF operation, respectively, without exceeding the 1.7 W/kg limit. The far-field wearable rectenna is demonstrated powering a Bluetooth Low Energy node using a BQ25504 DC-DC converter from a best-in-class low power density of 0.88 and 0.55 μW /cm2 on-body and in-space, respectively.

• Item Type: Articles
• Additional Information: This work was supported in part by the U.K. Engineering and Physical Sciences Research Council (EPSRC) under Grant EP/P010164/1, and in part by the European Commission through the EnABLES Project under Grant 730957. The work of Mahmoud Wagih was supported by the U.K. Royal Academy of Engineering and the Office of the Chief Science Adviser for National Security under the U.K. Intelligence Community Post-Doctoral Research Fellowship Programme. The work of Steve Beeby was supported by the U.K. Royal Academy of Engineering under the Chairs in Emerging Technologies Scheme
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Wagih, Dr Mahmoud
• Authors: Wagih, M., Komolafe, A., Weddell, A. S., and Beeby, S.
• College/School: College of Science and Engineering > School of Engineering > Systems Power and Energy
• Journal Name: IEEE Open Journal of Antennas and Propagation
• Publisher: IEEE
• ISSN: 2637-6431
• ISSN (Online): 2637-6431
• Published Online: 13 April 2022
• Copyright Holders: Copyright © 2021 The Author(s)
• First Published: First published in IEEE Open Journal of Antennas and Propagation 3: 398-411
• Publisher Policy: Reproduced under a Creative Commons licence