Tracking and launch control radar functions for the MIM-104 Patriot missile are the responsibility of the AN/MPQ-53 radar. The Patriot is primarily an anti-ballistic missile (ABM), also capable of surface-to-air missile (SAM) operation.
Fire control for the Patriot is especially complex, as it uses a "track via missile" technique. The fire control computer constantly merges data from an active radar in the missile, sent by data link to the ground station, with the ground-based MPQ-53 phased array radar.
Patriot missiles form the lower-level of a tiered ballistic missile defense system with the Terminal High Altitude Area Defense (missile). The AN/TPY-2 radar for THAAD can cue the AN/MPQ-53 radar; the Patriot missile itself has an onboard radar.