ABSTRACT
Synthetic aperture radar (SAR) is a complex system that integrates two major parts: data collector and image formatter. In the stage of data collection, a radar transmits electromagnetic waves toward the target and receives the scattered waves [1-21]. The transmitted signal can be modulated into certain types, commonly linearly frequency modulated with pulse or continuous waveform, with or without coding [22]. The process involves signal transmission from the generator, through various types of guided devices, to the antenna, by which the signal is radiated into free space and then undergoes propagation. During the course of propagation, the signal may be attenuated before and after impinging upon the targets, experiencing certain degrees of absorption and scattering. The measured scattered signal made in bistatic or monostatic configurations is essentially in the time-frequency (delay time-Doppler frequency) domain. The role of image formatter is then to map the time-frequency data into the spatial domain in which the targets are located [5,15,16,23-29]. The mapping from the data domain to the image domain, and eventually into the target or object domain, must minimize both geometric and radiometric distortions. This chapter provides an overview of two models that define the SAR operational process-physical model and system model-to facilitate our discussions in Chapters 5, 7, and 8.
