UHF radiowave propagation through forests

A model for UHF radiowave propagation through a forest of tree trunks, branches, and leaves is developed using the discrete scattering theory of Foldy and Lax. The forest is represented as a time-invariant ensemble of tree trunks, branches, and leaves all having prescribed location and orientation statistics. Tree trunks are modelled as infinitely-long, circular, lossy-dielectric cylinders; branches as finitely-long, circular, lossy-dielectric cylinders; and leaves as flat, circular, lossy-dielectric discs. Mathematical expressions are found for the effective dyadic susceptibilities of the equivalent continuous medium and for the specific attenuation associated with the (coherent) fields. Using biophysical parameters typical of a deciduous, hardwood forest, these expressions are found to be in reasonable agreement with experimental results. An anisotropic half-space model of the forest is reflected-, and lateral wave components of the mean field presented for a pulse of a few nanoseconds duration and a frequency of 600 Magahertz. A preliminary analysis shows the importance of the random (incoherent) field at a distance of one kilometer and at frequencies above 100 Megahertz.