Radiometric propagation studies of rain attenuation at 19.9 GHz in tropical region (Amritsar)

A 19.9GHz Dicke-switched radiometer in superheterodyne mode has been used for measurement of rain-induced attenuation of microwave at 19.9 GHz frequency. This paper presents the results of radiometric propagation studies conducted over a period of one year at Guru Nanak Dev University, Amritsar, for determining rain induced zenith path attenuation. The zenith path attenuation has been determined by the measurements of sky noise temperature received by the radiometer. The results obtained from the experiment are presented in the form of annual cumulative distributions of rain rate, sky noise temperature, and zenith path attenuation together with worst-month statistics. The cumulative distribution of zenith path attenuation predicted by using ITU-R model overestimates the measured cumulative distribution of zenith path attenuation. The variation of zenith path attenuation with respect to rain has also been shown in the measured results. On the basis of results it is concluded that attenuation up to approximately 18 dB can be calculated accurately from sky noise measured by radiometer at rain up to rain rates of 110 mm/hr. Zenith attenuation is well correlated with rain rate and can be estimated from regression analysis which has been obtained from the scattered values of measured zenith attenuation.