Hollow Cylinder Microwave Model for Stems

Abstract

Present electromagnetic models represent crop stems as full homogeneous cylinders. However, several ground measurements indicate that mature stems are hollow. In this paper, a model is presented which describes stems as hollow dielectric cylinders. The field on the surface of a hollow infinite cylinder is found at first, then applying the equivalence theorem, the scattered field from a hollow cylinder offinite length and any radius is obtained, and it is applied to the typical dimensions and permittivities ofwheat stems. The effects ofstem hollowness on microwave attenuation are investigated for a case study. Then, the extinction and bistatic scattering cross sections ofthe cylinder are included in the model developed at Tor Vergata University in order to study the effects ofstem hollowness on crop backscattering.