A model of UHF propagation in urban environment

The introduction of cellular mobile telephones and other communications systems in the UHF band (300 MHz-3 GHz) has imposed the need to predict radio path loss in urban environment between an elevated antenna and mobiles at street level. Response to this need has generally been the development of empirical prediction models based on collected measurements of received signal strength. Measurements are typically reduced to give average signal strength versus range from transmitter, assuming certain antenna height, etc., as well as to give statistical properties of variations about average. The influence of parameters such as building height, street width, terrain roughness, and slope are poorly understood and are accounted for by a series of correction factors. Propagation over the rooftops is the primary propagation path over the tops of the buildings, so the propagation through the buildings or between them are neglected. We deal with the influence of the two obstacles on the receiving field. The model describes the system consisting of the elevated fixed antenna (base station), mobile antenna located at street level and two rows of buildings of different heights and at different distances. The buildings, seen as the obstacles to direct wave path, are approximated with the knife-edge shape. We present Picquenard's model and our experiences with the model.