Investigation of the UHF (Ultrahigh Frequency) Mobile-Radio Propagation Channel in a Temperate-Zone Forested Environment

摘要

Experimental verification of the stochastic power-spectral-density theory of radio propagation, as applied to a mobile receiver in a forested environment, is presented. Using a novel technique to achieve fractional-hertz resolution of the diffuse and direct wave components of the Doppler-spread received spectrum, the resultant data taken at 432 MHz shows that the angle of arrival of the diffuse component of the incident energy at the receive antenna is described by an uniform probability density function for both vertical and horizontal polarizations. Given an 8.8 km transmission path with the signal penetrating 1.3 km of forest just before reaching the receiver, the ratio of coherent (direct wave) intensity to total received signal power is 42% for horizontal polarization and 5% for vertical polarization. The results of the research indicate that long transmission paths in foliage are better characterized by a forward-scattering mechanism than by a lateral wave model. (Author)