Prediction of Ka-Band Terrestrial Rain Attenuation using 2-year Rain Drop Size Distribution Measurements in Northern Taiwan

Abstract

In this paper, we study rain attenuation at Ka-band in northern Taiwan from long-term experimental measurements using a Ka-band (28.35 GHz) CW system at vertical polarization, optical rain gauge, and 2D optical distrometer that measures the rain drop size distribution (DSD). The DSD were measured and analyzed for different seasons under various rain rates. The variability of DSD in both space and time was clearly shown even in the not so large area of Northern Taiwan. It follows that a relationship between rain rate and DSD was established. From statistical regress, it was also found that the DSD follows the Gamma distribution best in most cases. Making use of the Gamma-distribution for DSD along with a two-year set of continuously measured data (2002–2003), a semi-empirical rain attenuation model was then developed. To validate the model, we compared it with the measured data. The results show that the proposed model matched very well with in-situ measurement from a two-year data set.