Collective scattering effects of trees generated by stochastic lindenmayer systems

Abstract

Recent studies indicate that at low microwave frequencies, branches and leaves scatter collectively so that the structure of the tree and the plant becomes important. We used stochastic Lindenmayer systems to generate trees with realistic appearances. Maxwell's equations are solved numerically for a tree grown in this manner. Collective scattering effects include phase difference among scatterers, as well as coherent wave interaction. We compare the scattering cross sections calculated by three approaches: coherent interaction model, coherent addition approximation, and independent scattering approximation. Numerical results show that the inclusion of coherent wave interaction among branches and leaves at low microwave frequencies can result in significant differences of polarization signatures and cross polarization from the other two approaches. It is also shown that results of the independent scattering approximation depend critically on how the branches are classified as independent scatterers. However, results based on wave approaches are not sensitive to such classification. © 1996 John Wiley & Sons, Inc.