A Simulation Study on the Influence of Leaf Orientation on Elliptically Polarized Microwave Propagation in a Coniferous Forest

Abstract

For an elliptically polarized wave propagating through a forested canopy a polarimetric propagation model has been developed to account for frequency, incidence angle, polarization, leaf orientation distribution, leaf size and moisture content. In this model the canopy is considered as a layer of randomly oriented scatterers. Then the loss and the depolarization factors for such a canopy are obtained via the coherent field and the coherent intensity approaches. The two approaches are shown to give identical expressions for the loss and the depolarization factor. For a coniferous canopy modeled as a layer of randomly oriented cylinders of finite length, the model gives values for the loss factor in agreement with the measurements. Numerical simulation is conducted at X-band to calculate the microwave transmission loss within a coniferous forest canopy. The simulation study reveals that the vegetation orientation distribution plays an important role in the transmission properties of an elliptically polarized wave. In addition, it was observed that the loss factor for a linearly polarized field was canopy-type-independent when the angle between the vertical axis and the incident electric field was around 50°.