Richard Klemm has recently retired after a distinguished career at FGAN FHR (now Fraunhofer FHR), a research institute working in the areas defence and security, and decades of service to the radar community.Ulrich Nickel has recently retired after a career as head of the research group Data Fusion for Array Sensors of the Sensor Data and Information Fusion (SDF) Department of Fraunhofer FKIE in Wachtberg, Germany.Christoph H. Gierull is a Senior Scientist with Defence R&D Canada, Ottawa Research Centre assuming the duties of Group Leader, Space-based Radar as well as Adjunct Professor at Laval University, Quebec and Simon Fraser University, British Columbia, Canada.Pierfrancesco Lombardo is Full Professor at University of Rome "La Sapienza", where he leads the "Radar, Remote Sensing and Navigation" (RRSN) group.