Optimized Wireless Power Transfer to RFID Sensors via Magnetic Resonance

Wireless powering of sensors through the strongly coupled magnetic resonance (SCMR) method at the RFID frequency of 27.2 MHz is studied here. The proposed system comprises of two single resonant loops and two self-resonant helical coils, in contrast to the two resonant loops traditionally used in RFID systems. The system is designed using simulation software and is validated by measurements. We illustrate that this design exhibits large efficiency at the desired frequency, which is significantly larger than the efficiency achieved by two conventional RFID loops. This is due to the large quality factor of the two single resonant loops as well as the inductively coupled pair of self-resonant helices employed in this SCMR power scheme.