This study undertakes the determination of suitable cutoff frequency for extracting scintillation amplitude dataset from radio propagation beacons on satellite link within Akure (7.17°N, 5.18°E), Southwest Nigeria. Attempt was also made towards evaluating the spectral characteristics of scintillation parameters through power spectra density (PSD) analysis. Concurrent measurement of satellite beacon signals and meteorological parameters was carried out on Earth-space path over the location for tropospheric amplitude scintillation studies. Tektronix Y400 NetTek Analyzer and Davis Vantage Vue weather station were used for beacon and weather parameters measurements at 1 second and 1 minute integration times respectively. Data spanning one (1) year of measurement were used for the investigation. Results show that extra contributions to signal distortions by non-scintillation mechanisms during extraction of scintillation dataset from satellite radio beacon series may be eliminated by using a cutoff frequency, f c of 0.25 Hz for high pass filtering. Also, spectral slopes with lower magnitudes were found to occur more predominantly than those with higher magnitudes.

Rain constitutes a major limitation to the performance and use of terrestrial and satellite communication systems with operational frequencies greater than 10 GHz. The situation gets further complicated by fast fluctuations in the received signal amplitude due to in homogeneities in atmospheric weather conditions; a phenomenon known as amplitude scintillation. The concurrent evaluation of the two phenomena guarantees a better fade margin determination for the planning of radio communication over any location. This work employs 3 years of in-situ measurement of temperature, humidity, rainfall rate and rainfall amount for the estimation of tropospheric amplitude scintillation and rain specific attenuation over Akure (7.17° N, 5.18° E, 358 m) South West Nigeria. Davis vantage pro weather station at 1-min integration time was used for the measurement and the ITU models for rain specific attenuation (ITU-R P.838-3) and amplitude scintillation (ITU–R 618-13) were employed for the estimation. Time series and statistical analyses of the phenomena show that rain attenuation is the more prominent cause of signal degradation at Ku-band frequencies. Nevertheless, the need to make an extra fade margin allowance of about 0.25 dB due to amplitude scintillation fade subsists to forestall any loss of synchronization on the link. Also, a 3-parameter power-law expression developed for estimating amplitude scintillation fade from rain attenuation performed excellently well, as indicated by average root mean square error (RMSE) and coefficient of determination (R²) values of 0.002151 and 0.8747, respectively.

Relationship between scintillation intensity (σ _χ ) and peak-to-peak amplitude (χ _pp) is important for mitigating scintillation effects on any communication link. This study employs linear, logarithmic and polynomial functions for fitting σ _χ and χ _pp in order to determine the best model for describing the variation of the former with the latter. It also examines the frequency of occurrence of scintillation intensity and the suitable probability density function for characterizing its distribution. Data used spanned 24 months, and were obtained from measurement of EUTELSAT W4/W7 satellite beacons on 12.245 GHz frequency, 1 s integration time and 53° elevation angle, at the Department of Physics, Federal University of Technology, Akure (07°17′N, 005°18′E, 358 m) Nigeria. Results show that logarithmic function performed best in modelling χ _pp from σ _χ as indicated by high coefficient of determination and minimal root mean sqaure error values. Strong scintillation events (σ _χ > 0.5) were also found to occur less frequently as sample interval increased. Lastly, lognornal, gamma and generalised extreme value (GEV) models were found suitable for describing σ _χ distribution.

To get the best performance for a broadband wireless access, this research aims to scale a Ku-band real-time rain attenuation data to higher frequencies and estimate the degree of fading that can be observed under such conditions. Data of simultaneous measurement of satellite radio beacons and rainfall parameters, carried out between January 2017 and December 2018, at Physics Department, Federal University of Technology (07.17°N, 05.18°E, 358 m) Akure, were used for the work. The radio beacon measurement, of horizontally polarized Eutelsat W4/W7 satellite signals at 12.245-GHz frequency, and received through a 90-cm parabolic antenna positioned at 53-deg elevation angle, was conducted at 1 s integration time using Tektronix Y400 NetTek spectrum analyzer. Measurement of rainfall parameters was done at 1-min sampling intervals using Davis Vantage Vue automatic weather station, which is co-located with the receiving antenna of the satellite receiver unit. Comparing measured and estimated attenuation values at 12.245 GHz for 1%, 0.1%, and 0.01% exceedance margins result in about 64%, 40%, and 55% relative error, respectively. Similarly, relative error values between estimated and scaled attenuation values for the same exceedance margins are 72%, 53%, and 27% for 16-GHz frequency, respectively, with similar values for the 20-, 30-, and 40-GHz frequencies as well. A power-law relationship between measured rain attenuation and rain rate was developed and used to generate a location-specific expression for computing rain attenuation. This was equally found to give better performance than the International Telecommunication Union model. The results obtained in this work provide useful information for radio engineers on the rain-induced attenuation needed for the design of radio communication system that can withstand poor weather conditions.

Radio signal transmitting above the ground surface experiences attenuation as a result of absorption by vegetation and hydrometeors, refraction due to turbulence in weather parameters; and reflection from ground surface. In this study, attempt was made to compute surface refractivity from its constituent parameters, and investigate its variation with leaf wetness and soil permittivity, at seven (7) different stations across Ondo state, Nigeria. Data for the research were obtained by in-situ measurement using Davis 3125 Vantage Pro2 weather station having sensors for measuring temperature, pressure, relative humidity, leaf wetness and soil moisture content. Measurement was carried out round the clock at 10 minutes integration time for a period of two weeks at each of the study locations, and for each of rainy and dry seasons. The soil moisture content was obtained at 30cm soil depth while leaf wetness was measured by attaching its sensor directly to a projected leaf-branch; and surface refractivity was computed from pressure, temperature and humidity data. Correlation analysis was employed to measure the strength and direction of the relationship between surface refractivity and each of soil permittivity and leaf wetness. Across the locations, R ranges from 0.38 to 0.9; and 0.04 to 0.7 for rainy and dry season respectively. The value of R is statistically significant at all the stations during the rainy season and majority of the stations during the dry season; signifying that surface refractivity exhibits good spatial and temporal relationship with soil permittivity and leaf wetness across the stations albeit with varying intensities.