Prediction of UHF path loss for forest environments

We describe radio wave propagation within terrain with vegetation, based on the measurements performed in a forested areas using low transmitter (TX) and receiver (RX) antenna elevations. We continue to investigate 3-D statistical multiparametric model of radio wave propagation above the rough terrain with some modifications made to describe multiple scattering of the signal field from randomly distributed trees, as phase screens, that model the random structure of trees with the rough surfaces and the irregular structure of branches and leaves, and other roughnesses placed on the ground surface. The scattering effects of trees and roughnesses are considered using a statistical description of an array of randomly distributed screens placed on a rough terrain. At the same time, an empirical short-range path loss model which is based on measurements carried out in typical forested areas in Denmark is considered. Comparison between results obtained from the statistical and the empirical models and those obtained from examination of the experimental data, as well as with the results of other existing models, is presented. It is shown that both models predict the exponential field intensity decay with the wide range of the power law index variations (from -2.5 to -4.3) with accuracy ±6 dB with respect to experimental data and which is better than that obtained from other existing theoretical models.