Monopulse radar

Monopulse radar is a radar system that compares the received signal from a single radar pulse against itself in order to compare the signal as seen in multiple directions, polarizations, or other differences. The most common form is an adaptation of conical scanning radar which compares the return from two directions to directly measure the location of the target. This avoids problems in decoding conventional conical scanning systems, which can be confused by rapid changes in signal strength. The system also makes jamming more difficult. Most radars designed since the 1960s are monopulse systems.

Description

Conical scan

Conical scanning is not considered to be a form of monopulse radar, but the following summary provides background that can aid understanding.

Conical scan systems send out a signal slightly to one side of the antenna's boresight, and then rotating the feed horn to make the lobe rotate around the boresight line. A target centered on the boresight is always slightly illuminated by the lobe, and provides a strong return. If the target is to one side, it will be illuminated only when the lobe is pointed in that general direction, resulting in a weaker signal overall (or a flashing one if the rotation is slow enough). This varying signal will reach a maximum when the antenna is rotated so it is aligned in the direction of the target, by looking for this maximum and moving the antenna in that direction, a target can be automatically tracked.