Increasing the performance of radar imaging systems will directly improve the effectiveness of automatic target recognition (ATR) systems. New ideas and solutions have been proposed in the recent NATO SET-250 Research Task Group (RTG) on multi-dimensional radar imaging, which initiated its activities in March 2017 and concluded them in October 2021. The goal of the SET-250 was to further develop systems and algorithms by using radar systems with extended dimensionality, such as multi-frequency, multi-polarisation and multi-view/multi-pass. In view of the increasing number of drone-like platforms, multi-dimensional radar needs to be assessed and compared against mono-dimensional radars in terms of their ability to provide valid support for classification and recognition of such targets. One of the major efforts that has been made within the RTG has been the organisation and execution of the RAF Spadeadam Trials, which have seen the employment of four different airborne radar systems. A range of unique results were obtained that are summarised in the various chapters of this book. This second volume of Multidimensional Radar Imaging contains declassified material that was generated within SET-250 and is key reading for anyone involved in researching or developing SAR radar imaging systems.