The report describes how simulations can be used for performance analysis of an AESA-based radar system mounted on a UAV. An AESA-based example system is analyzed in a use case that concerns protection of ships against anti-ship missiles. Performance is compared with an equivalent conventional radar, results are presented and conclusions are drawn. It is found that the example system shows significantly better performance; targets are captured 3-12 times faster and with a much higher tracking probability at large distances. Consequences of different design choices as well as the impact of clutter and errors in antenna modules are also included in the analysis. This work has been funded by the Swedish Armed Forces R&D programme for Sensors and low observables (FoT SoS, AT.9220420).