Microwave Wireless Powering of Sensored Agricultural Tile Drainages

In this article, a new technique for wireless powering of agricultural sensors buried deep underground is introduced and experimentally investigated. In this technique, the agricultural drainage tiles are utilized as waveguides to carry electromagnetic (EM) energy over long distances. By using high-efficiency rectifiers, the propagating EM waves are then converted into dc power to charge the batteries of underground sensors. A prototype 1 GHz rectenna system is fabricated and implemented on an 8 in tile to prove this concept experimentally. Various measurements are conducted for both the rectenna and the entire tile system, including realistic scenarios such as partially covered tiles and tile in the presence of water. Considering the emerging digital agriculture, the proposed technique will open the potential for detailed underground geochemistry studies, which will allow us to better monitor the transport of liquids and gases through millions of miles of agricultural tile drainage networks.