Effect of moisture content variation on dielectric properties of various plant leaves at microwave frequencies

Abstract

Overview

This study investigates the complex permittivity of Corn, Jowar, Ashoka, and Banana plant leaves over a frequency range of 500 MHz to 15 GHz using an Anritsu Shockline Vector Network Analyzer. Different moisture levels were tested to observe the changes in dielectric properties.

Findings

• The dielectric constant (ε') and dielectric loss (ε") decrease as the moisture content decreases within the tested frequency range.
• A critical moisture level (CML) was identified for each leaf type. Below this level, the values of ε' and ε" were relatively constant regardless of frequency changes.
• At moisture levels higher than the CML, ε' and ε" showed frequency dependence. Particularly above 3 GHz, ε" gradually increases, resembling the dielectric relaxation of water.
• Further comparisons of measured ε' and ε" values were made against predictions by Stogryn equations and Debye-Cole dual dispersion dielectric model, showing good agreement.

Conclusion

This study elucidates the intricate relationship between microwave dielectric properties and moisture content across different types of plant leaves, offering a detailed analysis and comparison with theoretical models.