Prediction of Target Detection Probability Based on Air-to-Air Long-Range Scenarios in Anomalous Atmospheric Environments

We investigate a target detection probability (TDP) using path loss of an airborne radar based on air-to-air scenarios in anomalous atmospheric and weather environments. In the process of calculating the TDP, it is necessary to obtain the overall path loss including the anomalous atmospheric environment, gas attenuation, rainfall attenuation, and beam scanning loss. The path loss including the quad-linear refractivity model and other radar input parameters is simulated using the Advanced Refractive Effects Prediction System (AREPS) software along the range and the altitude. For the gas and rainfall attenuations, ITU-R models are used to consider the weather environment. In addition, the radar beam scan loss and a radar cross section (RCS) of the target are considered to estimate the TDP of the airborne long-range radar. The TDP performance is examined by employing the threshold evaluations of the total path loss derived from the detectability factor and the free-space radar range equation. Finally, the TDPs are obtained by assuming various air-to-air scenarios for the airborne radar in anomalous atmospheric and weather environments.

Kajian Impelementasi Quality Control Faktor Bright Band dan Atenuasi Radar Cuaca C-Band

Weather radars have several limitations there are bright band echoes and attenuation of electromagnetic wave from radar’s beam. The purpose of this research is to conduct an analysis respect to the result of quality control from both of the limitations in 2019 which divide into four case study. Freezing level height of radiosonde used for support the identification activity of BBC phenomena. The result of BBC can reduce the BBE patterns however, it unable to function optimally in reducing all parts of the BBE patterns. Rainfall attenuation correction that have been done shows various results, either quantitatively or qualitatively. Attenuation correction is able to increase the rainfall value in product image SRI and PAC qualitatively. Quantitative analysis shows that the r and MAE values after attenuation correction of hourly rainfall have a good value besides that the attenuation correction in daily rainfall data is able to improve the estimate by 62.5%.

Analytical Approach to Critical Diameters in Raindrop Size Distribution in Durban, South Africa

Adequate information of the raindrop size distribution is very significant for the prediction and evaluation of attenuation signal due to rain. In this study, an analytical approach is adopted to determine the peak diameter where the specific rain attenuation is maxima in Durban (29º52'S, 30º58'E), South Africa; using the spherical raindrop shape at temperature T = 20ºC. The overall rainfall attenuation is computed by integrating over all the drop sizes and determine the differential change in the attenuation as observed over a fixed diameter interval, (= 0.1 mm). The critical diameters are the range of diameters where the rain attenuation is highly predominant, which constitutes the surface area under the curve and along the abscissa regions. The critical diameters are seen to coalesce around the peak diameter, at which the maximum attenuation occurs. The maximum specific rain attenuation peaks at the diameter It was observed that the peak diameter is frequency dependent while the parameters, µ, the mean and σ the standard deviation which determines the width of the distribution are found to be region-dependent. The peak attenuation for the stratiform rainfall type varies between 0.8 ≤ D ≤ 1.5 mm whereas for the convective rainfall, the specific rain attenuation peaks between 1.4 ≤ D ≤ 2.7 mm at all frequencies. A proper knowledge of the rainfall attenuation characteristics is useful for proper planning and for the purpose of link budget analysis by operators in this particular region.

Effects of Rainfall Attenuation on Frequencies 1 and 3 GHZ in Nigeria

Mobile communications are part of our everyday life. The non-ideal environment which is filled with many attenuation factors affects the electromagnetic waves, which radio communication depends. This study considers the spectral range of 1 and 3GHz. At these frequencies, interesting phenomena due to rain are supposed to happen. The study of this frequency spectrum has been undertaken in an attempt to evaluate the frequency dependence of rain effects on electromagnetic waves. The study of rain effects on communication presented in this study relied solely on rainfall data collected from Nigeria Metrological Agency (NiMet) station in Lagos, Nigeria. The months for January to December for 1981-2011 were summed together and the averages were determined. The average is then used to calculate the rain rate and rainfall attenuation using the extracted results for all the locations (Bauchi, Ikeja, Jos, Kebbi, Maiduguri and Warri). The results show that Warri has the highest rainfall rate followed by Lagos. Kebbi and Maiduguri has the least while Jos and Bauchi demonstrated moderate rainfall rates. This also deduced that attenuation has less impact on lower frequencies but increase with higher frequencies. The study reveals that at higher frequencies, the rainfall attenuation is observed to be greater.