Abstract:The amount of water deposits on the receiving dish antenna can cause additional losses and consequently contaminate the actual slant-path attenuation. Only a few research works have been reported in the literature on the measurement of wet antenna attenuation (WAA) and the technique(s) of extracting the losses from the total attenuation in tropical and equatorial climates, characterized with heavy rainfall intensities of convective kind. Therefore, the adverse effects of antenna losses due to rain on a 11. 843… Show more
“…This can cause additional attenuation called wet antenna attenuation. A series of experiments and studies on wet antenna attenuation have been conducted [24][25][26][27][28][29][30][31][32][33][34][35][36][37]. For example, an experiment on the wet antenna attenuation of terrestrial line-of-sight links in the 23-, 26-, and 38-GHz frequency bands formed the basis for a method that calculates the wet antenna attenuation using the annual statistical rain attenuation and rainfall rate [24].…”
Accurate prediction of rain attenuation is critical for the design of terrestrial line-of-sight link systems above 5 GHz, particularly for millimetre-wave frequency. Anomalous behaviour in the adjustment factor in existing rain attenuation prediction models is significantly greater than 1 at short distances and has been reported. To solve this problem and improve the accuracy, a rain attenuation prediction model for terrestrial lineof-sight links is proposed. The total rain attenuation described in the model accounts for the contributions of wet antenna attenuation and path rain attenuation. In addition, a rainfall rate adjustment factor is proposed. The proposed model has a root-mean-square error of 21.54% in prediction, which is an improvement compared to other existing models. Because the rainfall rate adjustment factor used in the model approaches 1 at short distances, the model can be applied to rain attenuation prediction for short-distance links. The results will assist designers to design link margins more accurately.
“…This can cause additional attenuation called wet antenna attenuation. A series of experiments and studies on wet antenna attenuation have been conducted [24][25][26][27][28][29][30][31][32][33][34][35][36][37]. For example, an experiment on the wet antenna attenuation of terrestrial line-of-sight links in the 23-, 26-, and 38-GHz frequency bands formed the basis for a method that calculates the wet antenna attenuation using the annual statistical rain attenuation and rainfall rate [24].…”
Accurate prediction of rain attenuation is critical for the design of terrestrial line-of-sight link systems above 5 GHz, particularly for millimetre-wave frequency. Anomalous behaviour in the adjustment factor in existing rain attenuation prediction models is significantly greater than 1 at short distances and has been reported. To solve this problem and improve the accuracy, a rain attenuation prediction model for terrestrial lineof-sight links is proposed. The total rain attenuation described in the model accounts for the contributions of wet antenna attenuation and path rain attenuation. In addition, a rainfall rate adjustment factor is proposed. The proposed model has a root-mean-square error of 21.54% in prediction, which is an improvement compared to other existing models. Because the rainfall rate adjustment factor used in the model approaches 1 at short distances, the model can be applied to rain attenuation prediction for short-distance links. The results will assist designers to design link margins more accurately.
Rain-induced attenuation above 10 GHz can be severe at heavy rain rates resulting in deep fading, which can negatively impact the quality of receive signal level at the Earth station receiver. The dearth of direct measurement data in most of the tropical and equatorial climates has motivated the campaign for collection of rain attenuation data on slant paths in these regions. This is mainly due to a huge receiver margin required for such measurement, and which is very difficult to obtain by using a spectrum analyzer. The measurement results of rain rates and rain-induced attenuation in vertically polarized signals propagating at 10.982 GHz in a tropical Malaysian climate are presented in this study. The measured attenuation is compared with large-scale prediction models. As shown in the statistically-tested results, the Bryant model yields the best overall fit, while the Crane model yields the worst overall fit. The results show that the models have relatively good prediction capabilities in the Malaysian tropical climate; however, their prediction errors still need to be minimized. Therefore, in this study, a correction factor is proposed to enhance their predictions.
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