This chapter provides the technical basis for imaging radar. It is broken into two parts, the first of which develops the system itself, showing how spatial resolution can be obtained and how an image is formed. The second section focuses on the target – which can be a discrete entity such as a house or a calibration device, or a distributed medium such as a vegetated pixel. Means by which the target can be described mathematically are derived by building on the radiation framework given in Chapt. 2.