Detection and Correction of Element Failures Using a Cumulative Sum Scheme for Active Phased Arrays

In this paper, we propose a novel technique that integrates the detection of element failures and the correction of damaged patterns into a systematic process for active phased arrays. The proposed technique uses the framework of mutual coupling method, and its kernel is based on a cumulative sum (CUSUM) scheme that monitors attenuators and phase shifters inside transmit/receive modules. The proposed method is organized into two phases. The phase one copes with the detection of failed components. By cumulating time-series data, the CUSUM can readily detect the defective elements even though very small shifts are examined. We test the effectiveness through a 448-element active phased array. The measured results show that no type I error is found, and the type II error of the most challenging scenario is significantly reduced. The phase two aims at the correction of patterns. By integrating the experimental result provided by the phase one and a least-squares method, the proposed technique can determine the new excitations leading to reduced sidelobe levels and a desired main beam characteristic. The capability is verified through three examples including linear and planar arrays. The results show that the proposed method can correct the damaged patterns with low computational complexity.