Research on Phase Characteristics of FDA‐AWACS and Direction Finding Mechanism Based on Anti‐Phase Method

ABSTRACT This paper addresses the vulnerability of airborne warning and control system (AWACS) platforms to precise interception by passive direction‐finding systems due to limited mobility and prominent electromagnetic signatures and investigates the phase‐frequency response characteristics of onboard frequency diverse array (FDA) radar and its deception mechanism against interferometric direction finders. Existing anti‐passive direction‐finding technologies such as signal quantisation reconstruction face severe payload, space and power constraints on AWACS, failing to reconcile the trade‐off between radar detectability and anti‐direction‐finding performance, which forms the core research contradiction of this study. FDA technology introduces carrier frequency modulation to construct a range‐angle‐time coupled radiation field, whose dynamic time‐varying characteristics and nonlinear phase distribution effectively disrupt the phase coherence reference of enemy passive direction‐finding systems. Its unique range‐angle coupling degrees of freedom are translated into concrete anti‐interferometric direction‐finding advantages by inducing triple interference effects on the receiving side, which cannot be achieved by traditional phased array radars. Through theoretical modelling and numerical simulation, this study systematically analyzes beamforming mechanism, phase pattern distortion and triple interference effects—instantaneous phase confusion, temporal accumulation bias, phase convergence disruption—induced by frequency diversity. Results reveal FDA's application potential for AWACS, offering key technical support to enhance survivability in complex electromagnetic environments.