Disclosed is an autonomous radar guidance of an otherwise radar-directed projectile (RDP). The preferred embodiment uses an inexpensive radar receiver with an inexpensive slow wave antenna, placed internally in a gun projectile, and on the surface of the projectile, respectively. The receiver detects the angle and range of the target relative to the body coordinates of the projectile. The radar receiver operates as a bistatic radar apparatus with the primary illumination emanating from the fire control radar directing the fire of the gun. When integrated with an on-board trajectory correcting system, such as divert thrusters of miniature proportions, the projectile autonomously refines its otherwise ballistic trajectory to the target. The trajectory refinements produce improved kills per round, with the potential for reducing the ammunition expended and time-loading on the fire control system and its guns. An alternative embodiment, in addition to receiving the target-reflected fire control emissions, receives and processes the fire control radar emissions directly in order to enhance homing accuracy.