Adaptive interference cancellation synthesized SMI and eigenspace-based method for HF surface wave radar

High frequency (HF) interference typically exhibits a time-varying or non-stationary spatial structure for the propagation through ionosphere. Adaptive interference cancellation methods are known to degrade in this case. In this paper, a new approach that effectively suppresses the non-stationary interference without degrading target visibility is presented for high frequency surface wave radar (HFSWR) circumstance. The proposed method synthesizes the sample matrix inverse (SM) and eigenspace-based beamformer, which maintains the beam pattern to keep the target response as well as cancels the interference mostly. A computationally efficient algorithm based on Lagrange multiplier methodology is proposed to compute the beamformer weights. Its excellent performance was confirmed by the experiment data of a real system.