3.1 Introduction 3.2 Radar Basics 3.3 Viewing Geometry and Spatial Resolution 3.4 Radar Image Distortions 3.5 Target Interaction and Image Appearance 3.6 Radar Image Properties 3.7 Advanced Radar Applications 3.8 Airborne vs. Spaceborne Radars 3.9 Airborne and Spaceborne Radar Systems 3.10 Endnotes