On the Passive Resolution of Broadcasting Targets with a Monopulse Antenna

This paper indicates a basic constraint on angular resolution of targets using monopulse measurements. The specific case at hand is the angular resolution of several broadcasting targets by a passive, standard, four-horn amplitude monopulse system. It is shown that when all broadcasting targets emit spectrally equivalent wide-sense stationary signals and the antenna and target geometry are fixed, the signals presented to the radar signal processor are equivalent to those of a canonical complex of threee broadcasting targets, one at an arbitrary angle θT, one at a null of the sum channel pattern, and one at a null of the difference channel pattern. In the case of broadband flat spectral transmission, two of the three targets in the canonical complex cannot be distinguished from receiver noise. A simple method for determining the angle (or angles) at which a monopulse antenna will attempt to track a broadcasting target complex is presented. Generalizations of this theory to active and/or more complicated monopulse systems are possible.