The design phase of an ESA project (MEKaP-MEO Ka-band Propagation) is described. The study, involving Politecnico di Milano, Sapienza Università di Roma, Instituto de Telecomunicações-Aveiro Pole and Thales Alenia SpaceItalia, aims at characterizing the main properties of the atmospheric radio channel of a MEO Ka-band SatCom system. The propagation campaign, lasting at least two years and including four ground receivers, will rely on the MEO O3b Ka-band satellite constellation, which has key characteristics for propagation measurements, such as continuous observation time (at least one satellite is always visible) and global coverage up to mid-latitudes. The experimental data collected during the campaign will be used to test and improve the available propagation models for non-geostationary systems and to extend the experimental database of radio regulatory bodies such as the ITU-R.