Parametric model of UHF/L-wave propagation in city with randomly distributed buildings

Abstract

For UHF/L-band radio waves most large city buildings practically are nontransparent and their sizes more larger than the wavelength, /spl lambda/. Moreover, in the cases when buildings are randomly distributed at the rough ground surface all specific properties of city topography form the specific conditions of wave propagation inside the street level. In such an urban environment we cannot use well known deterministic models and must use the statistical description of the real building pattern inside the city and need to derive the field strength on its base. To obtain the statistical description of the city topography map, we need detailed information about the spatial distribution of city buildings and natural obstacles, the sizes and ranges of reflected and diffracted surface sections of the ground relief and the spatial distribution of scattered points of each building placed in areas surrounding the receiver and transmitter antenna. Following a previous approach we introduce the parametric model and evaluate the average intensity of total wave field in the layer of city building with randomly distributed obstacles above the rough terrain by use of single-scattering and multi-scattering problems and taking into account the diffraction from the rooftops and building corners. Then, we present the results of numerous experiments carried out by the communication group of TADIRAN in various urban areas with non-regular distributed buildings and different position of transmitter and receiver antennas. Finally, the comparison between the theoretical prediction. based on the statistical parametric model, and experimental data is presented. The possibility of using this parametric model for prediction of loss characteristics in clutter urban conditions with randomly distributed obstacles placed at the rough terrain is examined.