EXPERIMENTAL VALIDATION OF DIELECTRIC MODELS FOR SUGARCANE VEGETATION AT C-BAND MICROWAVE FREQUENCY

Abstract

Monitoring vegetation using satellite data at microwave frequency is a non-conventional method and is an essential requirement for agriculture management. The interaction of the microwave signal from the satellite sensors with the vegetation is recorded in terms of the backscattering coefficient for active sensors and in terms of emissivity and brightness temperature for passive sensors. The interaction of the microwave with vegetation is greatly influenced by one of the target properties i.e., complex dielectric constant. Dielectric models of vegetation explicate the relationship between microwave response and physical characteristics of parts of vegetation. There is a great need for experimental determination of the complex dielectric constant of vegetation and validation of the complex dielectric constant with dielectric models. The present work consists of laboratory measurements of the complex dielectric constant of sugarcane vegetation at C - band microwave frequency and analyses of the variations in the complex dielectric constant with moisture content. The Von – Hippel method is used to perform these measurements at room temperature. The experimental data is then compared with dielectric models namely Carlson Formula, Matzler, and Debye Dual dispersion model to discuss the suitability of these models for the prediction of the dielectric response for sugarcane vegetation. Further, the experimentally measured data of the complex dielectric constant is used to calculate theoretically the emissivity and brightness temperature using the Fresnel equations as these parameters are significant for microwave remote sensing of sugarcane vegetation.