A theory and model for wave propagation through foliage

A theory is presented and a model is developed to predict the effects of foliage on a line-of-sight propagating field. In view of the sparse concentration of foliage, the Foldy-Twersky theory for wave propagation through discrete random media is used to obtain the complex propagation constant for the coherent field. On the basis of the measurements of Stutzman et al. (1979), the dominant foliage components are taken to be Rayleigh-like in their scattering and absorbing characteristics. The effective fractional volume of foliage comprising the Rayleigh components is constructed as a function of frequency using forest stand table data. Trunks and branches are modeled as Rayleigh cylinders; leaves are ignored because of their small total volume. The model fails above the frequency for which the effective fractional volume goes to zero. The model provides reasonably good agreement with propagation measurements and is capable of explaining some of the observed polarization effects.