UHF (Ultrahigh Frequency) Radiowave Propagation through Forests

摘要

A model for Ultrahigh Frequency radiowave propagation through a forest of tree trunks, branches, and leaves which had been first described in a previous report has been extended. Forest characterization includes the dielectric properties of green wood and leaves, tree trunk diameter distributions, branch orientation, and canopy structure. Plots of the effective dyadic susceptibility and specific attenuation for homogeneous and non-homogeneous forests of tree trunks are presented. The theory of the anisotropic forest slab model is extended to include the forest floor and multiply-reflected space and lateral waves. Basic transmission losses versus frequency for various radiolink geometries are plotted, as are the responses to five-nanosecond pulses at 600 MHz. Incoherent multiple scattering in a two-dimensional forest of tree trunks, small or large with respect to the wavelength, is studied. Plots are shown for single-tree scatter patterns, albedos, and total cross-sections versus frequency, as well as normalized coherent and incoherent scattering intensities versus distance, and normalized frequency- and space-correlation functions. (Author)