Reducing the decoupling errors in adaptive beamformers by multistage wiener filter

The mutual coupling between antenna elements significantly deteriorates the performance of antenna arrays. Many decoupling techniques have been developed over the years. A key step of decoupling processing is to obtain the decoupling matrix (or mutual impedance matrix). However, the accurate decoupling matrix is unavailable in practice because mutual coupling depends not only on the geometry of the array, but also on the excitations of the elements. Unfortunately the decoupling errors can also lead to severe performance degradation of antenna arrays, especially for the adaptive beamformers. In this paper we propose a decoupling error reduction method based on the reduced- rank multistage Wiener filter (MWF). The reduced-rank MWF projects the weight vector of beamformer onto the Krylov subspace, which has a regularization effect that can reduce the performance degradation caused by random errors in the array. Besides having a simple implementation structure, the proposed method is computationally efficient. Moreover, simulation results show that the proposed method considerably improves the signal-to-interference-plus-noise ratio (SINR) of the beamformer when there exist decoupling errors in the array.