The rain Attenuation Characteristics at 12.7 GHz on Earth-Space Path in Bangkok

This paper presents a statistical analysis of the rainfall rate and the rain attenuation data on satellite to ground propagation path. By measuring 12.7-GHz beacon signal attenuation from satellite and the rainfall rate continuously from February 2000 to August 2002 and January 2003, respectively. The smaller integration time interval yields the higher the rainfall rate. Correlation between 10-second and 1-minute integration time of the rainfall rate is presented. Yearly cumulative distribution functions were then compared with predicted models Two predicted models, ITU-R [5] and Crane Global [4] models, for the rain attenuation and ITU-R [6] model for the rainfall rate. The Crane Global model for the rain zone H provides close predicted values to measured ones. For the rain zone G, the Crane Global model provides close values to ITU-R model; both are smaller than measured ones. The ITU-R method is proven to underestimate the rain attenuation in the equatorial region like Bangkok