Upper- and lower-bound evaluations in microwave urban LOS propagation

To model the path-loss characteristics in microwave urban line-of-sight (LOS) propagation, we performed measurements at frequencies of 3.35, 8.45, and 15.75 GHz in metropolitan Tokyo. The actual breakpoint distance was shorter than the theoretical one because of the influence of vehicles, pedestrians, and other objects on the road. This effect can be characterized by the effective road height. We also found that the breakpoint disappeared when the receiving antenna height approached the effective road height. Based on these breakpoint characteristics, we propose new upper- and lower-bound formulas for LOS path losses in urban environments