Development of EM energy harvester for self-sustained IoT enabled sensor nodes

In this paper, a microstrip patch antenna is designed employing a rectifying circuitry to be used in the agriculture sector. The antenna works with 2.45-GHz Bluetooth/ wireless local area network. The antenna has been simulated and fabricated applying a low-priced FR4 substrate having thickness measured as 1.6mm and has a miniature dimension of 18mm×30mm. To achieve better impedance matching and improved return loss, a stub technique using slots has been employed. A single-stage rectifier is deployed with an L-type impedance-matching network. The rectifier has been fabricated on the FR4 substrate. An output voltage of 3.63V is measured across a capacitor of value 470pF. This output voltage is sufficient to drive electronic sensors deployed in the agriculture sector to assess soil temperature, moisture, and mineral contents. The application of this rectenna circuit in the next-generation Internet-of-Things IoT devices will lower the charging need and will also facilitate the battery-less operation.