Diurnal variation of slant path Ka-band rain attenuation at four tropical locations in India

Rain attenuation is very severe at Ka and higher frequencies especially in tropical regions. The conventional fade mitigation techniques are not be able to mitigate this severe fade and hence, suitable diversity technique is required for this purpose. In this paper, rain characteristics and slant path rain attenuation at 30 GHz using synthetic storm technique has been presented. Three years of high resolution rain rate data obtained from disdrometer at four tropical and equatorial locations in India have been utilized. The results indicate that the fade margin requirement is very high (above 50 dB at 30 GHz) for 99.99% link availability for these locations. However, the diurnal analysis shows that in most of the places, the rain occurrence is much less in morning/early-morning hours and therefore, the fade margin requirement will be considerably lower (around 30 dB at 30 GHz) in the morning hours compared to the afternoon hours. The result indicates the suitability of using selective time period for high link availability data communication over the locations studied.