Land Vehicle-Based Wireless Power Transfer Through Soil for Enabling Batteryless Underground Soil Moisture Sensing Application

This paper reports the design and field demonstration of a land vehicle-based wireless power transfer system that can enable a batteryless underground soil moisture sensing application. The wireless power transfer system consists of a tuned primary coil exhibiting a 40cm-diameter with 2-turn, which is inductively coupled to a secondary coil buried in the soil, tuned to the same frequency at 2MHz, exhibiting 6cm-diameter and 1-turn while being interposed between two ferrite layers. The prototype system is optimized to transmit 20mW over 20cm distance (18cm-deep soil with a 2cm air gap above the ground) to energize an underground soil moisture sensor.