Close Proximity Effects of Metallic Environments on the Antiparallel Resonant Coil for Near-Field Powering

This study verifies close proximity effects of metallic environments on the antiparallel resonant coil for near-field powering based on the theoretical analysis and experimental measurements. Compared to the conventional coil with a forward loop, frequency shifting of the antiparallel resonant coil which consists of forward and reverse loops with opposite-direction currents is unchanged regardless of the proximity of metallic plates. Furthermore, highly efficient near-field powering for metallic objects can be achieved with the antiparallel resonant coil because of the added magnetic field caused by the image current of the metallic plates.