Fig. 3: Simulation-based characterization of HARVEST’s sensitivity to changes in soil VWC and EC.
a Variation in the \({S}_{11}\) spectra as each nail probe—reference, VWC, and EC—was successively connected to its designated SRR on the antenna. b Recorded resonant frequencies for each SRR upon successive integration of the reference, VWC, and EC monitoring probes. c Changes in the \({S}_{11}\) spectra when HARVEST was embedded in soil and VWC was incrementally increased from 5% to 20% insets (a–c): illustrates the different stages of sensor probes attachment and placement in various soil conditions. d Calibration curve showing the frequency shift of the VWC-associated SRR (middle peak, SRRVWC) as a function of VWC. e Changes in the \({S}_{11}\) spectra when HARVEST was placed in soil with EC varied from 0.2 to 0.8 dS m⁻¹. f Calibration curve showing the change in amplitude of the EC-associated SRR (first peak, SRREC) as a function of EC. (Color-coded resonance peaks in spectra: Orange: EC resonator (SRREC), Blue: VWC resonator (SRRVWC), Green: Reference resonator (SRRRef)). Source data for Fig. 3 are provided as a Source Data file. Plant pot icons: Created in BioRender. Rahimi, R. (2025) https://BioRender.com/b8eqflj.
