An analytic model of specific attenuation due to rain

Rain attenuation is one of the dominant factors in determining the reliability of microwave and millimeter systems; the specific rain attenuation is a fundamental quantity in calculation of rain attenuation statistics for terrestrial and earth-space paths. The power-law relationship of specific rain attenuation y/sub R/ (dB/km) and rain rate R (mm/h), y/sub R/ = kR/sup a/ is widely used and the values of k and a are usually tabulated for specific frequencies. The values tabulated are particularly convenient for estimation of specific attenuation in experimental applications or link designs at specific frequency, and the interpolated values should be used for other frequencies. However, It would be quite useful for system studies requiring calculations at many frequencies to have simple analytic expressions which give results in good agreement with the values tabulated. Regression to determine the relationships between the parameters, k and a, and frequency has been done and the regressed expressions given.