Rain attenuation measurements using synthetic storm technique over Ahmedabad

Generation of rain attenuation time series is important for understanding the rain fade characteristics in the absence of actual fade measurements. In this paper, performance of synthetic storm technique (SST) is assessed for time series generation over Ahmedabad, a tropical location in India. Radiometric measurements at 20.2 GHz are used for attenuation calculation in zenith direction. Rain rate information is obtained from a collocated tipping bucket rain gauge. From the analysis, it is found that SST is a suitable simulation tool to estimate the fade characteristics from the rain rate measurements over this region. Rain attenuation exceedance distribution is calculated using SST along the slant path of proposed GSAT-4 satellite and it is observed that for 99.9% service availability at least 8 dB and 18 dB fade margin is required for 20.2 and 30.5 GHz links, respectively.