A robust multi-target angle pairing method for bistatic HFSWR

The bistatic high-frequency surface wave radar (HFSWR) system with two widely separated receivers offers enhanced localization accuracy but requires reliable multi-target parameter association. Existing angle pairing methods inadequately utilize multistatic observational diversity and degrade significantly when targets exhibit small angular separations or angular overlap from a single station’s perspective. This paper proposes a signal-level multi-target angle pairing algorithm for bistatic HFSWR system to address these challenges. Specifically, a spherical wave model is employed to link the echoes received by different subarrays, enabling the construction of the cross-correlation matrix. A subspace-based 2D-direction-of-arrival (DOA) loss function is then derived. Furthermore, to mitigate rank deficiency caused by insufficient angular separation, we introduce a block forward-backward spatial smoothing (BFBSS) technique, with a PM-ESPRIT-based criterion guiding its application to avoid aperture loss. Finally, a reduced-dimension DOA estimator is employed to obtain the final DOA estimates and pairing results while reducing computational complexity. Simulation results validate that the proposed algorithm delivers superior pairing robustness and estimation accuracy, even when targets exhibit angular overlap from the perspective of a single receiving station.