RAIN ATTENUATION AT C, KU AND KA BANDS DETERMINED USING EARTH- SATELLITE LINK BEACON SIGNALS IN TROPICAL REGION

Abstract

Spectrum congestion in frequencies below 10 GHz is pushing satellite network operators to migrate to higher bands. Nonetheless, availability and system performance can be seriously degraded at higher frequency bands when the operating link experiences severe rainfall intensity. A study has been carried out to investigate the different consequences of rain on C, Ku, and Ka band satellite links. Cumulative distribution function (CDF) analysis was performed to obtain the time exceedance percentage, which represents the percentage of link availability in determining the required fade margin. It was observed that rain attenuation experienced by the C band link was very minimal and can be assumed to be negligible, implying that this link was not severely affected by rain. On the other hand, the attained Ku and Ka bands rain fade at 99.9% availability were 10 and 29 dB respectively. The Ku band link attenuation was 32 dB at 99.99% availability. The attenuation at 99.99% availability for the Ka band link was not able to be compiled as rain attenuation exceeded 33 dB, the receiver system started to provide a saturated value. A few extrapolation techniques were used to determine the Ka band attenuation values above 33 dB. Second-degree polynomial was found to fit well with the measurement data since it has lower root mean square error (RMSE) as compared to other techniques applied.
Keywords: Rain attenuation; tropical region; C, Ku and Ka bands; Earth space satellite link; fade margin.

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