Study of variation of complex permittivity of tree leaves with moisture content, over microwave frequency range

Abstract

The vector network analyzer (Anritsu Shockline Model-MS46322A) is used for the measurement of complex permittivity of the Banyan (Ficus benghalensis), Neem (Azadirachta indica), and Papaya (Carica papaya) tree leaves over 0.5 GHz to 15 GHz frequency range. The dielectric constant (ε’) and dielectric loss (ε”) of the leaves are found to decrease with decrease in moisture content at given frequency. Further the ε’ of leaves decreases with increase in frequency at a fixed moisture content. ε” of wet leaves increases with increase in frequency at higher moisture content towards relaxation frequency of water but at lower moisture contents in the leaves, ε” decreases with increase in frequency. The measured values of ε’ and ε” are compared with the values calculated using Debye-Cole dual-dispersion dielectric model, and results are found to match very well with the values calculated using the model.