A two-step scanning policy for early target detection in electronically scanned antenna radars

We consider a surveillance radar system equipped with an electronically scanned antenna and study a scanning policy divided in two phases, namely, a search phase, where the antenna beam rotates to illuminate the monitored area, and a revisit phase, where some ambiguous returns are revisited for further investigation. The revisit phase introduces additional degrees of freedom for system design, that can be exploited to improve the early-warning capability of the radar. Numerical examples are provided for a realistic scenario.