Self-resonant coil with coaxial-like capacitor for wireless power transfer

This paper proposes a self-resonant coil with a flexible coaxial-like capacitor and a helical coil for wireless power transfer based on magnetic resonance. The coaxial-like capacitor is used to adjust a target resonant frequency and to prevent variation of the target resonant frequency due to external objects. The capacitor can be integrated spatially adaptively with the helical coil. Due to property of its low loss, the entire self-resonator has still high Q-factor. To verify its properties and analysis results, two types of self-resonant coils were fabricated and tested. The calculated parameters of the coil are very consistent with the measured ones. The measured efficiency is also in good agreement with the theoretical one.