Estimation of the Propagation Impairments of Satellite Systems Design in the SHF and EHF Bands in Subtropical Region

摘要

Super high frequency (SHF) to extremely high frequency (EHF) bands offer many advantages such as scalability, high asymmetrical traffics and the ability to permit highspeed digital communications due to larger bandwidths among others. However, frequencies greater than 10 GHz leadto signal fading due to physical phenomena related to the propagation of radio waves through the atmosphere. In order to ensure the necessary Quality of Service (QpS) against various transmissions and other impairments at these coverages, not only rain attenuation, which is recognized to be the most significant impairment must be considered. Extra fading due to tropospheric constituents, like snow, water vapour, clouds, gaseous and scintillations caused by air turbulence must also be considered. In this paper, the effects of rain attenuation A (dB) in a heavy rainfall sub-tropical regions for SHF and EHF bands at a given carrier frequency in an average year has been estimated by the synthetic storm technique (SST) and an associated formula that links A to frequency for fixed probabilities. Additional fading due to water vapor, clouds, oxygen and scintillations is estimated by applying the ITU-R formulae. The total attenuation (rain attenuation plus other propagation impairments) obtained is applied to Quadrature Phase Shift Keying (QPSK) modulation scheme en route Earth-satellite- Earth link, with regenerative transponders, in order to obtain a specify maximum bit error rate (BER) tolerated by the end users.