Browsing by Author "Omotosho, T."

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    Analysis of Attenuation Due to Atmospheric Gases Prediction Models at Ota, Nigeria
    (Science and Technology: Developments and Applications Vol. 7, 2025) Akinwumi, A.; Omotosho, T.; Usikalu, M.; Adewusi, M.; Ometan, O.; Emetere, M.
    The theory explaining the interaction between molecules and radiation of gases in telecommunication ascertained the fact that microwave signals experience significant attenuation that can appreciably degrade the quality of signal transmissions. Millimeter and sub-millimeter wave signals experience scattering and absorption while propagating through the atmosphere. The demand for satellite services is rapidly increasing on a daily basis. One of the major concerns for satellite telecommunication designers is the impacts of gas attenuation on earthspace path links, most importantly in tropical areas. This research has been directed at the analysis and comparison of gas attenuation prediction models at Covenant University, Ota, southwest Nigeria (Lat: 6.7 o N, Long: 3.23o E). Gas attenuation data were collected from the spectrum analyzer and Davis automatic weather station for a period of five years (April 2012- December 2016) from Astra 2E/2F/2G Satellite link set at an elevation angle of 59.9o on 12.245 GHz. The monthly gas attenuation was analyzed and compared with existing gas attenuation prediction models that could provide a guide to microwave propagation engineers in the tropical region. The results suggest that even during clear-sky, gas attenuation still poses a threat to the design of satellite communication on the earth-space path. The results also suggest that even during clear-sky, gas attenuation still poses a threat to the design of satellite communication on the earth-space path. Likewise, the same pattern was observed from 2013 to 2016 where Salonen’s model was reported as the lowest model and Liebe’s model gave the highest value. Therefore, the ITU-R model may be more accurate for modelling gas attenuation for the region. Hence, the statistics provided in this work will help engineers in planning and designing good telecommunication systems in the tropical region.
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    Comparative Study of Tropospheric Scintillation Prediction Models at Covenant University, Ota, Southwest Nigeria
    (Science and Technology: Developments and Applications Vol. 6,, 2025) Akinwumi, S.; Omotosho, T.; Usikalu, M; Adewusi, M.; Ometan, O.
    Knowledge of tropospheric scintillation is an important phenomenon in the design of satellite communication systems especially in the case of signal propagation. Tropospheric scintillation occurrences transpire to be one of the key signal impairments that affect earth-satellite paths in modern earth-space communication systems, most importantly at higher frequency bands (both uplink and downlink). One year of scintillation data from January 2015 to December 2015 extracted from Astra 2E/2F/2G Satellite link measurement installed at Covenant University, Ota (Lat: 6.7o N, Long: 3.23o E) Southwest Nigeria, at an elevation angle of 59.9o and a frequency of 12.245 GHz was used in this study. The analysis and the result were compared with some reputable scintillation prediction models to obtain the best performance model for the Ota region. Evaluation of four existing clear-sky scintillation models namely: ITU-R, Karasawa, Otung and Van de Kamp models have been presented in this study. From the result, it was discovered that the Karasawa model gives the lowest percentage error rate for both fade and enhancement of about 0.57% at 0.1 percent of the time and 6.93% at 0.01 percent of the time respectively and therefore was best found fit for the prediction of propagation impairment for the region. However, the model should be tested further using higher frequency bands such as Ka and V bands to confirm the accuracy of the model. The information provided in this study is useful in fading margin for antenna sizing and performance needed for satellite communication links in the region. The ground measurements from Ota have confirmed that the Karasawa model gave the best prediction for tropospheric scintillation intensity for Ota and its environment.