TABLE OF CONTENTS A radar is an electromagnetic system for detection, location, and sometimes for recognition of target objects, which operates by transmitting electromagnetic signals, receiving echoes from target objects within its volume of coverage, and extracting location and other information from the echo signals [1, p. 854], This definition is a logical extension of the original term Radio Detection and Ranging. As the technology and applications of radar have advanced over a period of some 70 years, the requirements and expectations for performance beyond mere detection have become more demanding. Radar system analyses must now provide quantitative estimates of performance in all the radar's functions, for a variety of target types in a variety of complex environments. The purpose of this book is to summarize the methods and models used in these analyses.
This chapter will discuss the basic functions and subsystems of radars and the radar range equations that establish the regions within which targets can be detected. Subsequent chapters will consider the characteristics of noise and other interference components entering the receiver, the ratio of target signals to this interference required to perform a particular function, and the means by which this ratio can be obtained in the actual environments where radars operate.
The two most basic functions of radar are inherent in the acronym: detection and ranging. Angle measurement is also a basic function of most radars, and doppler velocity is often measured directly as a fourth basic quantity. Resolution
