MIMO radars. What are they?

Two classes of MIMO radars are briefly considered. MIMO radars with colocated antennas and coded signals represent a new and prospective concept. MIMO Radars with widely separated antennas (“Statistical MIMO radars”) are a particular case of well-known Multisite (Multistatic) radar systems. Most results presented by the authors of “Statistical MIMO radars” were obtained under much more general conditions and published many years ago. Besides, ignoring some specific features of radar by the authors of “Statistical MIMO radars” has led to serious errors.