MEASURED SCATTERED SIGNALS AT 4 GHz CONFIRM STRONG SPECULAR REFLECTIONS OFF BUILDINGS

摘要

For the frequency coordination of new microwave links in urban areas,new models of interference are needed which accurately take into account scattering from buildings.In previous work,we have shown analytically that large specular reflections of microwave signals off butidings are Dossible and that such reflected signals would preclude the success of a link constructed in those direclions.We report measurements of building reflections in the Fresnel region which clearly show the existence of large specular reflections which would cause severe interference into radio links.The measured specular reflection is 20 to 30 dB highor than the diffusely scattered energy and is caused by reflection from a building illuminated by a sidelobe 17 dB below the boresighi beam of the transmitter indicating that a reflection in the main beam would cause interference which may be 37 to 47 dB highor than that predicted by terrain scatter models.