The extragalactic sources at mm wavelengths

The frequency range between 10 and 100 GHz, contains continuum signals of interest both for astrophysical and cosmological studies. However, astrophysical continuum signals along our line of sight towards the CMB modify (like in the case of the Sunyaev-Zel''dovich effect) or contaminate (like the signals from the Milky Way or from other galaxies) the CMB signal, complicating the full exploitation of the CMB maps. So, characterizing the foreground properties in the same observational frequency range of CMB observations, in addition to being of interest per sè, is of crucial importance to fully exploit the data collected by CMB-targeted missions. In this thesis we have discussed the characterization of the radio source emission in the high radio frequency band through the observations of the AT20G survey and the detections of the NEWPS catalogue, we have investigate the Sunyaev-Zel''dovich effect focussing on its observability and on theoretical predictions for proto-galaxies and we have dealt with radio sources as a CMB foreground, with special reference to the ESA Planck mission.