Propagation study at 4065 meters of altitude: Attenuation due to gases at Ka, Q, V and W bands using radiosonde observations

As frequency increases, gaseous attenuation in Earth-Space links becomes more relevant. High altitude sites can be an interesting option for future potential deployment of ground stations for satellites with broadband communication links under low gaseous attenuation conditions. The present paper is part of a study aimed to characterize the propagation conditions at high altitude sites, as a collaboration between Universidad Privada Boliviana and Agencia Boliviana Espacial, which operates a Satellite Ground Control Station located above 4000-m of altitude. A 2-year database of radiosonde observations carried out once a day at La Paz/El Alto Airport, located 13 km away from the station, at 4065-m of altitude and a height difference of 50 m, is exploited with the aim of estimating gaseous attenuation at Ka, Q, V and W bands. The calculations have been performed using the line-by-line method of the ITU-R P.676 Recommendation and compared to approximate methods. Results show a higher impact of attenuation caused by oxygen at 40, 50 and 75 GHz in relation to water vapor effects and prediction errors of approximate methods between 5% and 10% under these particular geographical conditions.