Electromagnetic Wave Scattering From Vegetation
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This dissertation contains the theoretical study of microwave scattering from vegetated media and the development of microwave scattering models with applications to these media. A vegetation canopy may consist of deciduous or coniferous leaves, branches, and trunks with certain size and orientation distributions. The formulation of the scattering model for each element of the canopy is carried out and its scatter patterns versus its size and orientation for like and cross polarizations are computed and presented. In particular, an extension is made where vegetation with a compound-leaf pattern is considered. For this type of vegetation, several leaves that form a specific pattern will scatter coherently as a group as opposed to each leaf scattering independently. Hence, a basic scattering element is a compound leaf with a specific leaf-pattern. Based on the study of scattering patterns of different vegetation elements, the scattering models for different vegetation media are formulated. For a leafy vegetation, we model it as a scattering layer with a given type of leaf. For a forested area, we treat it as a two-layer medium: the layer on top is the crown layer consisted of leaves and branches and below it is the trunk layer. In order to verify the validity of the theoretical models for different types of vegetation canopy, extensive comparisons between models and measurements are carried out .