Two year rain attenuation statistics over a line of sight terrestrial microwave link operating at 30 GHz in tropical region Amritsar (India)

The effect of precipitation present in the path of earth-space communication links, in terms of fading of the signal, is well known. The calculation of fade margin required for 99.99 % of the time-availability of such links requires the knowledge of rain rate and attenuation levels for 0.01 % time of the year. The International Telecommunication Union (ITU-R) has given recommendations regarding the estimation of rain rate and attenuation levels but it has been found that the recommendations are not suitable for tropical regions whereas some degree of agreement has been found for temperate regions. The paper presents the results of two year rain attenuation measurement program conducted in a tropical site Amritsar (India). The results are based upon the rain rate data collected by using a tipping bucket rain gauge and receiver data of LOS link operating at 28.75 GHz. The results presented in the form of cumulative distributions (CD) of rainfall rates and rain attenuation are compared with the calculated ones in accordance with relevant ITU-R recommendations. The experimental results are different from that predicted by ITU-R.