OVERVIEW

The detection and measurement performance of a radar system can be modeled and analyzed with confidence only when the target and environmental conditions are correctly represented by their models. Since a wide variety of targets are encountered, we must find target models of sufficient latitude to accommodate wide variation in characteristics of individual targets at specific times. The importance of the signal-to-noise power and energy ratios has been shown in the previous two chapters. Knowledge of the RCS of the target is essential in any such calculation. Although there are a few cases in which target RCS is constant, it generally varies considerably as the aspect angle changes, as internal motions of the target change its shape, and as radar frequency or polarization is varied. These changes force us to use statistical methods to describe the RCS. The power of interfering signals backscattered from clutter (objects other than the desired target) is also modeled statistically, and as a function of radar-clutter path geometry, radar wavelength and polarization, and type of clutter.

In measurement of target position and velocity, there are target characteristics other than its echo amplitude that are important. The echo signal consists of components scattered from points distributed over the surface of the target. The amplitude and phase of each component varies as a function of time, aspect angle, and radar frequency, and the interaction of these components affects the radar measurement process. This chapter summarizes these target characteristics and describes them in ways that permit accurate...