Characterisation of building scatter of signals at microwave frequencies

In assessing the effect of site shielding where multi-path interference is a distinct possibility, building, vegetation and terrain scatters are also important factors apart from diffraction around shielding obstacles. Particularly, building scatter has been long identified as a significant interference source in urban environments. In site shielding situations, distances from possibly scattering buildings are considerably limited by space in urban areas, typically in a range from a few hundred to a few thousand meters. At microwave frequencies, buildings are immensely large relatively to the wavelength. This means that distance is usually only a very small fraction of the Rayleigh far field distance, such as the order of one hundredth. The paper describes the development of a prediction model suitable to assess scattering behaviours of buildings in site shielding. The validity of this model has been examined against measurements made from a reflector and buildings at a frequency of 11.2 GHz