Propagation studies at Ku-band over an earth-space path at Kolkata

Abstract

Propagation measurements at Ku-band over an earth-space path have been carried out at Kolkata (22º34' N, 88º29' E) by receiving a signal at 11.172 GHz from the satellite NSS-6 (geostationary at 95ºE). The amplitudes of the co-polar signal and the cross-polar component have been monitored along with the measurements of rain rate and drop size distribution by an optical raingauge and a Joss-type disdrometer, respectively. Three phenomena studied with the experimental data are rain attenuation, depolarization and scintillation. The rain attenuation observed experimentally tallies well with the values obtained from the point rain rate using a simple attenuation model, if the rain rate is low (less than 20 mm/h). The depolarization, indicated by an enhancement of the cross-polar component of the signal, is well correlated with the rain attenuation. The presence of large rain drops is found to have a more dominant role in determining the extent of depolarization than affecting the co-polar attenuation. The scintillation observations associated with the rain events indicate that the standard deviation of fast fluctuations increases with rain attenuation following a power-law.