Seamless metamaterial integration into slotted resonators for compact high-performance near-field wireless power transfer system design

Abstract This paper presents a novel design concept for near-field wireless power transfer (WPT) systems that leverages the seamless integration of metamaterials (MTMs) into slotted resonators. This approach enhances magnetic field ( $$\textbf{B}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>B</mml:mi> </mml:math> ) distribution, strengthens evanescent wave coupling, and hence improves overall WPT performance. An MTM structure exhibiting negative permeability at the operating frequency of 433 MHz was designed and incorporated into a square-slot-based resonator. Electromagnetic (EM) analysis revealed increased current density and subsequently enlarged $$\textbf{B}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>B</mml:mi> </mml:math> around the resonator. Additionally, impedance matching, key parameter extraction, and equivalent circuit (EC) modeling were performed using the effective J-inverter method. The developed WPT system, with compact dimensions of 30 $$\times$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mo>×</mml:mo> </mml:math> 30 $$^{\text {2}}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mmultiscripts> <mml:mrow/> <mml:mrow/> <mml:mtext>2</mml:mtext> </mml:mmultiscripts> </mml:math> , achieved a power transfer efficiency of 82% at 33 mm. The design was experimentally validated, showing excellent agreement among EM simulations, EC modeling, and measurement results. Finally, performance comparison with other reported systems confirmed the superiority and practical effectiveness of the proposed design in enabling compact and highly efficient WPT systems.