Improved target direction‐of‐arrival estimation using multiple adjacent beams for airborne phased array scanning radar

Abstract

In order to avoid straddling loss, airborne phased array scanning radar transmits beams with small step angle, and then the same target can be detected again and again in multiple adjacent beams through azimuth scanning. Therefore, considering its long-range surveillance and high revisit rate, the authors may assume that the azimuth angle of the same target almost keeps unchanged during multiple beams. Furthermore, they can also model the target complex amplitude from each beam as an unknown deterministic signal with amplitude and phase difference that accounts for the antenna pattern and sampling starting time. A direction-of-arrival estimation algorithm that utilises multiple beams to obtain an accurate target angle is proposed. The signal model that jointly considers received data from multiple adjacent beams is introduced, and the maximum likelihood (ML) estimation of target angle in noise and jamming sceneries is obtained. The performance of proposed method is investigated through Monte-Carlo simulations and compared with both the Cramer-Rao lower bound and with conventional ML technique that utilises one beam. Simulation results validate the effectiveness of the presented algorithm.