Field Analysis and Measurement of Antiparallel Resonant Loop for Wireless Charging

Among electromagnetic compatibility considerations, radiated emissions constitute one of the areas of highest concern because wireless power and communications systems operate by emitting magnetic fields. In this paper, the radiated field of the antiparallel loop is theoretically analyzed and experimentally verified at distances in the near- and far-field regions. A reduced magnetic field strength of approximately 6 dB is obtained with the proposed antiparallel loop when compared to a conventional loop at the measuring distance up to 10 m. Furthermore, since portable devices with an NFC function require the configuration of simple structures for wireless charging, the proposed design concept for antiparallel resonant loops offers considerable benefits as it suppresses the generation of electromagnetic interference noise.