A Conformal Split-Ring Loop as a Self-Resonator for Wireless Power Transfer

Jingchen Wang, Mark Paul Leach, Eng Gee Lim*, Zhao Wang, Zhenzhen Jiang, Rui Pei, Yi Huang

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

17 Citations (Scopus)


A conventional printed spiral coil (PSC) has a self-resonant frequency and its equivalent circuit is a parallel inductor-capacitor (LC) circuit. It is desirable to use PSCs in wireless power transfer (WPT) applications; however, these are most commonly constituted by a series-primary and series- or parallel-secondary circuit. This paper proposes a printed conformal split-ring loop with the characteristic of a series LC circuit at its resonance frequency. Regarding the loop as a self-resonator, a magnetic-resonance coupled (MRC) WPT system with series-primary and secondary operating at 433 MHz in the industrial scientific and medical (ISM) band is presented. The maximum measured power transfer efficiency is 87.9% at a transfer distance of 22 mm, the best-reported result for such a configuration.

Original languageEnglish
Article number8721462
Pages (from-to)911-919
Number of pages9
JournalIEEE Access
Publication statusPublished - 2020


  • Wireless power transfer
  • magnetic resonance coupling
  • near fields
  • printed spiral coils
  • split-ring resonators

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