Rain attenuation prediction at 6.75 GHz in Malaysia using rain gauge and radiometer measurements

Attenuation due to rain is an important constraint in microwave radio link design especially at frequencies above 10 GHz in temperate climates. However, it has been shown in some literature that rain also plays an important role in radio signal attenuation below 10 GHz in tropical and equatorial climates which experience higher precipitation rates. Due to the scarcity of rain attenuation data for the tropical region, a definitive attenuation model can only be derived from long term data collection in this region. In this paper, the results of two years rain rate data and six months radiometer data are presented. The rain data is measured using a tipping bucket type (0.5 mm) rain gauge with one minute integration time. The radiometer data were taken for 45 and 90 degrees elevation using a dual channel unbalanced Dicke radiometer. Both the rain gauge and radiometer data were analysed in event and statistical terms. The attenuation derived from radiometer measurements gives a higher value of attenuation compared to rain gauge measurements. It was also found that at for 0.01% of the time, the rain rate is lower than that given by the ITU (formerly CCIR) for P region climate