Rain Intensity Estimation Using Satellite Beacon Signal Measurements A Dual Frequency Study

The Alphasat Scientific Experiment is a satellite propagation experiment representing the continuation of the European Space Agency's (ESA's) commitment to the characterization of the Ka and Q band radio channel. Among several institutions across Europe, Budapest University of Technology and Economics is also taking part in the propagation experiment. The measurement site is located at the university, continuously recording the unmodulated carrier levels of 39.402 GHz and 19.701 GHz along with the main meteorological parameters. The most important phenomenon that causes attenuation is the rain, considering the millimetre wave propagation. Rain intensity is usually measured by different kind of weather sensors, like tipping-bucket, drop-counter type rain gauges or disdrometers. Nevertheless, a point rainfall rate measurement e.g. at the location of the terrestrial endpoint of the radio link usually not correctly represents the rain distribution along the radio path, especially in case of long terrestrial or satellite connections. This paper evaluates the relationship between rain attenuation and rainfall intensity by using the experimental data of Ka/Q band. We extract the rain intensity information by using the measured attenuation on the radio path. For this purpose we process both the Ka and Q-band beacon signals that are transmitted by the Alphasat Aldo Paraboni payload. The dual-frequency approach allows the comparison of the results that may lead to a more accurate attenuation to rain intensity calculation method in the future.