Comparison between radiometrically measured and predicted attenuation at 23.8 and 31.4 GHz in temperate climate

The atmospheric attenuation in the absence of liquid water, both rain and clouds, is considered as a relevant parameter for the design of low availability satellite communication systems. The absorption due to oxygen and water vapour is derived from experimental radiometric measurements, carried out for one year in Roma, Italy, and calculated with the ITU-R algorithm, based on climatic surface data. The comparison shows that clear sky attenuation, mostly due to water vapour, can be accurately estimated by simplified models, the corresponding discrepancy with the measured “truth reference” being, however, dependent upon the degree of air humidity. The resultant indications are of relevance for the design of commercial systems, especially in those climates, such as the tropics, where the vapour density is usually higher with respect to temperate zones