Studies on Ku-band Propagation over Earth-Space Paths and Related Rain Parameters at a Tropical Location

Propagation measurements at Ku-band over an earth space path have been carried out at Kolkata (22°34’N, 88°29’E) by receiving a signal at 11.172 GHz from the satellite NSS-6 (geostationary at 95°E) since June 2004. The amplitudes of the co-polar signal and the cross-polar component have been monitored along with rain rate and drop size distribution measurements by an optical raingauge and a Joss-type disdrometer, respectively. The relationship between rain attenuation over the earth-space path and the rain rate gives an assessment of raining conditions along the satellite path. The degradation in the cross-polar discrimination (XPD) has been obtained during rain events and compared to the ITU-R model. Fast fluctuations of the satellite signal amplitude are studied to indicate the effect of small scale irregularities associated with the rain events. TRMM satellite data obtained with PR and TMI indicate that the rain rate has a distinct control of rain height which increases with the former, the relationship depending on the type of rain. The propagation measurements and TRMM data have been used to study the features of rain attenuation over Kolkata.