Abstract
A fully passive, 3D-printed wireless sensor for detecting soil moisture levels is presented in this paper. The sensor comprises a capacitively loaded antenna whose resonant frequency changes in response to soil moisture level. Results show that a variation in soil moisture levels of 20% by weight causes a change in frequency of 16.66 %. A low-cost sensing scheme for large area soil monitoring is proposed in which the sensors are dispersed in the agricultural land and work in combination with unmanned aerial vehicles (UAVs) which record the sensor readings and send the data to a ground station. Calculations show that the sensors can be read by a UAV flying at an altitude of 298 m. Additive manufacturing technique namely 3D-printing has been used for the fabrication of the sensor.