A Study of Rain-Induced Attenuation on Terrestrial Paths at Ku, K and Ka Bands Over Akungba-Akoko, Nigeria

Abstract

Rain attenuation is one of the main impairments that limit radio signals in high rain rate regions, especially at higher frequencies such as Ku, K and Ka frequency bands. Therefore, rain rate and rain attenuation predictions are some of the fundamental steps to consider when designing terrestrial line of sight communication links. The paper presents rain rates at 1 min integration for 0.01 percentage of time exceedance using Chebil, Lavergnat-Gole and power law conversion rain rate models for Akungba-Akoko, Ondo State, Nigeria. This was achieved using 5 min integration rainfall data for a period of three years. The rainfall data were measured by the Nigerian Environmental and Climate Observing Program (NECOP) instrumentation installed at the Adekunle Ajasin University, Akungba-Akoko. The estimated rain rates were used as input parameters to compute the total rain-induced attenuation at 0.01 percentage of time exceedance for 15 GHz, 23 GHz and 30 GHz through a path length of 10 km for vertical and horizontal polarizations, using Moupfouma, ITU-R and Lin attenuation models. Lavergnat-Gole conversion model gave the highest rain rate estimation in the region, while Lin attenuation model gave the highest estimation for total rain-induced attenuation, which is also closest to that of the ITU-R attenuation model. Generally, for all operating frequency bands and rain rates, the total rain-induced attenuation at horizontal polarization is higher compared to that at vertical polarization. Results from the analysis provide a broad knowledge of rain attenuation in the tropical region which can serve as a good preliminary design tool for terrestrial link engineers