Research on Amplitude Characteristics of FDA‐AWACS and Direction Finding Mechanism of Anti‐Beam Search Method

ABSTRACT

Aiming at the problem that airborne warning and control systems (AWACS) are prone to passive positioning due to electromagnetic radiation and have limited survivability in modern electromagnetic countermeasures, this paper focuses on the amplitude–frequency response characteristics of frequency diverse array (FDA)‐based AWACS and the deception mechanism of antibeam search direction finding, aiming to provide theoretical support and technical solutions for antipassive direction finding. This paper constructs multidimensional radiation field analytical models for one‐dimensional and two‐dimensional FDAs, revealing their core characteristics such as distance‐angle‐time three‐dimensional coupling, multidimensional periodicity and self‐scanning without phase shifters. The principle and error mechanism of beam search direction finding are clarified, and the deception mechanism is deduced from three aspects: destruction of direction‐finding prerequisites, interference with measurement processes and degradation of direction‐finding accuracy. Three core interference mechanisms are proposed, and a quantitative model for direction‐finding deception error is established. Simulation results show that the frequency offset increment is the core control parameter; when it is ≥ 50 kHz, stable deception can be achieved for far‐field direction‐finding systems within 10–100 km and the effectiveness is more significant for high‐speed passive direction‐finding systems with a scanning speed of ≥ 1.5°/μs. The asymmetric frequency offset configuration of two‐dimensional FDAs and nonlinear frequency control functions can enhance the deception effect.