Weighted-Correlation Near-Field Scanning for Far-Field Radiation Source Identification

The precise identification of electromagnetic interference (EMI) sources is the primary task to be addressed when a product’s radiation emission exceeds compliance standards. However, when multiple sources work at the same frequency but with different time-domain characteristics (e.g., radiation signals are complex modulated signals), it is difficult to directly determine the location of the radiation sources by traditional near-field scanning (NFS) with spectrum analyzer measurements. In this paper, a novel weighted-correlation NFS method is proposed, which can intuitively display the far-field radiation source distribution by calculating the near-to-far field correlation. The proposed method performs the short-term fast Fourier transform (STFFT) analysis on the far-field and near-field signals, then performs deferred cross-correlation analysis on the time-frequency spectrum, and finally calculates the weighted-correlation map based on the NFS results. Two simulation cases are presented to demonstrate the effectiveness of the proposed method in accurately locating far-field radiation sources.