TABLE OF CONTENTS In this chapter, passive DF systems used for radar warning and ELINT purposes will be described in terms of the DF concepts and antenna technologies presented thus far. System configurations typical of present-day implementations will be detailed in various generic block diagrams. In each case, the reader should identify the type of system and, if monopulse, determine the class and method of satisfying the criteria for angle extraction. This recognition process will develop an appreciation of the potential a given system has to attain specific goals. Some systems are designed for warning, some for data gathering, and some for high accuracy; in each case, a specific design offers advantages and disadvantages. A wide instantaneous bandwidth receiver may be readily jammed; a narrow bandwidth system will lose data but may be more accurate measuring the data it does process. It is hoped that by following these rules, the reader will develop an insight into system "entropy," or overall capability to achieve a desired objective.
In the microwave region, angle-of-arrival data is used primarily as a means of determining the line-of-bearing of a signal or the position of an emitter with respect to either the DF host vehicle or the overall situational geography. The first case is usually for threat warning, where the identification, direction, and rate of closure are important factors for self-protection. The second case is for electronic order of battle (EOB) for the purposes of calibrating the signal environment, to determine the circle of...
