Modeling And Simulation of Rain Attenuation Effect on Microwave Propagation

Rain attenuation poses a significant challenge to satellite communication networks, resulting in signal degradation, increased path loss, and reduced coverage, particularly in tropical regions and at frequencies above 10 GHz. This study examines average rain-induced attenuation and rainfall data for microwave links operating at 11 GHz, 13 GHz, 14 GHz, 18 GHz, and 23 GHz, with a rainfall rate of 50 mm/h, over a terrestrial link in Port Harcourt, Rivers State, Nigeria. The city's terrain, encompassing urban, suburban, and rural environments, serves as a representative model for broader applications across Nigeria. Situated in the coastal region, Port Harcourt experiences annual rainfall ranging from 2000 mm to 2400 mm. Satellite communication is frequently hindered by persistent rain attenuation, occasionally leading to outages lasting minutes, hours, or even days. Data for this analysis were sourced from the Nigerian Meteorological Agency (NIMET), and also the International Telecommunication Union's Radio-wave Propagation (ITU-R P.618-13) model was employed to estimate long-term rain attenuation for these frequency bands. Python and Excel software were used for data analysis and simulation. The results obtained show that higher frequencies experience greater attenuation. As the frequency increases, the rain attenuation also increases significantly. At any given percentage, attenuation increases with frequency. At 0.001%, 23 GHz has the steepest curve due to its higher attenuation value of 57.63 dB. Lower frequencies have relatively flatter curves, representing reduced attenuation. This helps to clearly show the trend at very small percentages of time. Attenuation decreases rapidly as the percentage of time exceeds increases. Also, the analysis revealed significant attenuation from June to September, coinciding with the peak rainfall period in the region. This study underscores the substantial impact of rain fade on signal attenuation at higher frequencies in Port Harcourt. The findings provide critical insights for satellite communication engineers to optimize the planning and design of microwave links in the region throughout the year.