A fire-control radar (FCR) is a radar which is designed specifically to provide information (mainly target azimuth, elevation, range and velocity) to a fire-control system in order to calculate a firing solution (i.e. information on how to direct weapons such that they hit the target(s)). Such radars typically emit a narrow, intense beam of radio waves to ensure accurate tracking information and to minimise the chance of losing track of the target. Some modern radars have a track-while-scan capability enabling it to function simultaneously as a fire-control radar and a search radar. This works either by having the radar switch between sweeping the search sector and sending directed pulses at the target to be tracked, or by using a phased-array antenna to generate two (or more) discrete radar beams and dividing them between both tasks.
Fire-control radars operate in three different phases:
Designation or vectoring phase: The fire-control radar must be directed to the general location of the target due to the radar’s narrow beam width. This phase ends when lock-on is acquired.
Acquisition phase: The fire-control radar switches to the acquisition phase of operation once the radar is in the general vicinity of the target. During this phase, the radar system searches in the designated area in a predetermined search pattern until the target is located or redesignated. This phase terminates when a weapon is launched.