The CSG SAR is the heart of the remote sensing system conceived by the Italian Space Agency (ASI) and by the Italian Ministry of Defence (I-MoD) for taking the baton from "COSMO' SkyMed" (CSK) [1]. This microwave imaging sensor is a multi-mode X-band radar, designed to implement a variety of acquisition techniques, with a wide span of performance and functionalities. The requirements of the system have been defined by ASI and I-MoD and negotiated with Thales Alenia Space Italia S.p.A. (TAS-I) to provide improved performance exploiting the full bandwidth that will be permitted by the updated ITU regulation, including additional modes and novel acquisition techniques (patented by TAS-I), together with a new set of experimental modes operating also in squinted modalities. In addition to that, CSG will assure continuity with the services already provided by CSK. This paper gives an outline of the architecture of the CSG SAR, illustrates the key features of the hardware designed for enabling the new required capabilities, and presents the results of a performance prediction based on the current stage of development of the radar. © VDE VERLAG GMBH · Berlin · Offenbach.