The measurement and model construction of complex permittivity of vegetation

The complex permittivity of targeted objects is an important factor that influences its microwave radiation and scattering characteristics.In the quantitative research of microwave remote sensing,the study of the dielectric properties of the vegetation to establish the relationship between its specific physical parameters and complex permittivity is fundamental.In this study,six categories of vegetation samples were collected at the city of Zhangye,a key research area of the Heihe watershed allied telemetry experimental research.The vector network analyzer E8362B was used to measure the complex permittivity of these samples from 0.2 to 20 GHz by the coaxial probe technique.The research focused mainly on the corn leaves,and an empirical model was established between the gravimetric moisture and the real/imaginary parts of complex permittivity at the main frequency points of microwave sensors.Furthermore,the empirical model and the classical Debye-Cole model were compared and verified by the measured data collected from the Huailai County of Hebei Province.The results show that the newly- established empirical model is more accurate and more practical as compared to the traditional Debye-Cole model.