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Gamma model is used to model the drop size distribution of Singapore. Specific rain attenuation is calculated using forward scattering coefficients and using ITU-R P.838-3 recommendations for vertically polarized waves at 11 GHz, 20 GHz, 30 GHz and 38 GHz at different elevation angles. Slant path attenuation is calculated using the specific rain attenuation at different elevation angles using ITU-R...
This paper proposes a model for predicting the rain attenuation along the earth-space slant propagation path. The experiment results collected for rainfall rate and for rain attenuation is described. The rainfall rate from a rain gauge and the rain attenuation for three satellite signal in both the Ku and Ka band are analyzed and used. Based on the rainfall rate data and the Ku and Ka-band beacon...
The prediction model proposed by Karasawa and Matsudo is a simplified method for the conversion of 1-minute rain rate from hourly rainfall rate data. In this paper, studies on the Karasawa and Matsudo model have been done to obtain suitable parameters for the local climatic conditions in Singapore. Data from recent years are used to derive the a and b parameters of the Karasawa and Matsudo model....
The preliminary results of the analyses performed suggest that the rainfall rate with 1 min integration time has a good agreement with the rainfall rate predicted from ITU-R model, regardless of yearly or worst month statistics. However ITU-R P.618-9 tends to underestimate the rain attenuation for the earth-space link in tropical areas like Singapore. A modified model of rain attenuation prediction...
This paper presents the specific attenuation (gamma) at 11 GHz based on measured drop size distribution (DSD). The influence of particular rain drop sizes (diameters) is presented with the conclusion that the drop diameters from 0.771 mm to 5.3 mm are important for DSD and specific rain attenuation (gamma) calculations. DSD for different rain rates are plotted using lognormal model with maximum likelihood...
This paper analyzes and presents the measured drop size distribution (DSD) for five rain rates 4.20, 22.80, 66.54, 100.57 and 141.27 mm/hr in Singapore (1deg20'N, 103deg41'E). The ranges of rain drop diameters that are critical to the DSD are identified and the significance of their relationship is analyzed. The modified gamma model is used to describe the DSD in Singapore. Root mean square error...
This paper investigates the dynamic property of a tropical forested channel due to the weather effects on UHF radio wave propagation. In this study, continuous wave (CW) envelope fading waveforms are recorded over a period of 50 seconds with static antennas. The weather induced temporal variation has been analysed with the Rician distribution function. Special attention is given to the combined effect...
In this paper, the relationship between the rainfall rate statistics from the Doppler radar system and the one minute integration time rain distributions from a rain gauge network was studied. With these investigations, a simple framework of converting the radar rainfall rate statistics to its equivalent one minute rain rates was suggested. The prediction results were evaluated, and good agreement...
Raindrop size distribution has been measured in Singapore (1deg20'N, 103deg41'E) for evaluating the rain effects on microwave propagation. In this paper, a lognormal model suitable for the region is proposed which is useful for the prediction of rain attenuation. Using the measured data, different estimators for the lognormal model are used to study the performance and find the optimal estimator for...
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