Microwave path-loss characteristics in an urban area with base station antenna on top of a tall building

Much research has been reported on the microwave band as a powerful means of achieving 4th-generation mobile communications systems. The focus of this research, however, has been propagation characteristics under the assumption of low antenna height for base stations in a microcell environment. This paper, in contrast, clarifies microwave path-loss characteristics in an environment where the height of the transmitting base-station antenna is higher than that of surrounding buildings. Path-loss characteristics (attenuation coefficient, corner loss, relative loss, and standard deviation) in a non-line-of-sight (NLOS) environment with high antenna height were found to be quite different than those of a conventional low-antenna-height environment. This is because the propagation mechanism of primary waves is significantly altered by the change in antenna height. It was found, in particular, that rooftop diffracted waves come to dominate in a high-antenna-height, NLOS environment