Frequency scaling of rain attenuation based on microphysical characteristics for SatCom links

'Frequency scaling' relates to the variation of propagation effects as a function of frequency. The frequency scaling ratio between the Ka and V bands, derived using a model based on an integrated parameter such as rain rate, is inadequate. In fact, propagation variations due to the microphysical characteristics of rain need to be considered in order to improve the existing scaling model, particularly at higher frequencies. Many different laws for raindrop size distribution, combined with one year of measured drop size distribution (DSD), are used to study propagation sensitivity to drop size and shape. A statistical study of the normalised DSD has been carried out and two scaling models are proposed in which microphysical considerations are taken into account. Italsat and Olympus data have been used to validate this approach.