scholarly journals Realizing Efficient Wireless Power Transfer in the Near-Field Region Using Electrically Small Antennas

10.5772/28897 ◽  
2012 ◽  
Author(s):  
Ick-Jae Yoon ◽  
Hao Ling
Keyword(s):  
Near Field ◽  
Wireless Power Transfer ◽  
Field Region ◽  
Power Transfer ◽  
Wireless Power ◽  
Electrically Small Antennas ◽  
Small Antennas

scholarly journals Separation-Independent Wearable 6.78 MHz Near-Field Radiative Wireless Power Transfer using Electrically Small Embroidered Textile Coils

Energies ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 528 ◽  
Author(s):  
Mahmoud Wagih ◽  
Abiodun Komolafe ◽  
Bahareh Zaghari
Keyword(s):  
High Efficiency ◽  
Near Field ◽  
Wireless Power Transfer ◽  
Mobile Systems ◽  
Power Transfer ◽  
Wireless Power ◽  
Electrically Small Antennas ◽  
Link Efficiency ◽  
Free Band ◽  
End To End

Achieving a wireless power transfer (WPT) link insensitive to separation is a key challenge to achieving power autonomy through wireless-powering and wireless energy harvesting over a longer range. While coupled WPT has been widely used for near-field high-efficiency WPT applications, the efficiency of the WPT link is highly sensitive to separation and alignment, making it unsuitable for mobile systems with unknown or loose coupling such as wearables. On the other hand, while ultra-high frequency (UHF) and microwave uncoupled radiative WPT (0.3–3 GHz) enables meters-long separation between the transmitter and the receivers, the end-to-end efficiency of the WPT link is adversely limited by the propagation losses. This work proposes radiative WPT, in the 6.78 MHz license-free band, as a hybrid solution to separation-independent WPT, thus mitigating the losses associated with coil separation. Resonant electrically small antennas were fabricated using embroidered textile coils and tuned using L-matching networks, for wearable WPT. The antenna’s efficiency and near-fields have been evaluated numerically and experimentally. The proposed WPT link achieves a stable forward transmission of S 21 > − 17 dB and S 21 > − 28 dB, independent of coil separation on the XZ and XY planes respectively, in a 27 m 3 volume space. The presented approach demonstrates the highest WPT link efficiency at more than 1-m separation and promises higher end-to-end efficiency compared to UHF WPT.

Sign in / Sign up

Export Citation Format

Share Document