Propagation measurements at microwave frequencies for microcellular mobile and personal communications

A series of measurements was conducted in both rural and semiurban areas to measure radio propagation characteristics at microwave and millimeter-wave frequencies in a microcellular mobile radio environment where transmission is essentially line-of-sight (LOS). Measurements were made at 11 GHz with a fixed-site antenna located at the side of the road at heights of up to 30 ft. Data have been taken with both omnidirectional and directional antennas on the mobile, to compare received signal characteristics. It was found that, in rural and semiurban environments, propagation is dominated by interference between the direct ray and a specular, roadway-reflected ray. The average power received does not decay any faster than 1/r² over the measured range of transmitter-to-receiver separation. A wideband communication channel looks feasible, since the dual-ray interference effects and the random components of the received signals can be overcome by simple methods such as higher antenna directivity or space diversity