Stochastic model for pulsed radio transmission through stratified forests

The paper describes a stochastic radiowave propagation model useful for assessing the effects of forests and other vegetation on communications signals in the UHF band. The stochastic electromagnetic theory employed as the basis of this model considers the forest as a planar, stratified, anisotropic, discrete, random medium, bounded above by air and below by ground, of randomly positioned and oriented canonical scatterers representing the principal forest constituents (tree trunks are represented as infinitely long, parallel, circular, dielectric cylinders; branches as short ones; and leaves as flat, circular, dielectric discs). A physically appealing representation for the mean (coherent) field component of the propagating radio wave has been obtained by recognising that the ensemble of discrete scatterers can be replaced by an equivalent continuous medium described by an effective dyadic permittivity ¿¿¿¿. The associated electromagnetic boundary-value problem is solved to identify the principal contributions to the mean field: the direct wave, the reflected wave and the lateral wave. Because the equivalent continuous medium characterised by the effective dyadic permittivity ¿¿¿¿ is linear, Fourier-transform techniques have been employed to generalise the model so that it accommodates arbitrarily modulated waveforms.