11- and 18-GHz radio wave attenuation due to precipitation on a slant path

Measurements of attenuation at 11 and 18 GHz from precipitation have been made on a slant path over a three-year period in the Tokyo area using a sun tracker and a radiometer. Simultaneous rain attenuation measurements of a 2.9-km terrestrial path at 19 GHz were used to clarify the correlation characteristics between the terrestrial and the slant paths. The following results are presented: frequency, seasonal, annual, and elevation angle dependence of rain attenuation, rain rate distribution, effective distance, correlation characteristics of attenuation between slant and terrestrial paths, attenuation due to snowfall, and site diversity effect for a separation of 14.3 km at 18 GHz.