Figure 8
From: A biodegradable chipless sensor for wireless subsoil health monitoring
Experimental studies on DIRTS buried in the field when interrogated by a stationary reader and a drone-mounted reader (a) Photograph of the portable reader assembly in the field. (b) Photographs of the portable antenna loaded onto a stationary mount demonstrating RD = 10 cm, and RD = 40 cm. (c) Measured \({S}_{21(cal)}\) plotted as a function of frequency for a VWC of 6% and 9% when RD = 10 cm, and RD = 40 cm. (d) Photograph of the drone-mounted antenna hovering over a sensor tag. Inset shows the sensor tag placed at a depth of 5 cm before filling up the bored hole. (e) Measured \({S}_{21(cal)}\) plotted as a function of frequency as recorded by the drone from an elevation of ~ 40 cm for ground truth VWCs of 6% and 14.5%. (f) Comparison of the results obtained from the portable reader on the stationary mount and the drone with respect to the calibration curve obtained from the lab tests.
