This paper proposes an innovative omnidirectional amplitude-comparison monopulse direction-finding deception method to address the protection requirements of frequency diverse array （FDA） airborne warning and control system （AWACS） against anti-radiation missiles （ARMs）. By establishing an FDA radar spatial radiation model and analyzing the omnidirectional amplitude-comparison direction-finding mechanism of an ARM’s passive radar seeker （PRS）， the study reveals the mechanism by which FDA generates azimuth deception through the synergistic effect of frequency offset increment Δf and power ratio Δ. Simulations demonstrate that under a configuration of 10 array elements， a 3 GHz carrier frequency， and half-wavelength array spacing， the system can induce a maximum direction-finding deviation of 2°. Error analysis shows that beamwidth variation and antenna aperture offset further exacerbate direction-finding errors. This technology effectively interferes with the PRS error voltage function and normalization processing， providing an effective electronic countermeasure for AWACS against precision strikes.

With the rapid development of unmanned aerial vehicle（UAV）， UAVs have been widely used in civil and military fields. Small UAVs with “low flight height， slow flight speed and small dimensions” characteristics are especially convenient and flexible to use and relatively inexpensive. They can be used for reconnaissance， surveillance，suicide attack and other task purposes， posing a serious threat to daily air defense security and important assets protection. The main threat patterns of the small reconnaissance UAV and payload capabilities are analized. The denial distance requirements to small UAVs are also proposed， which can provide reference for anti-UAV system development .