Investigation of an Iterative Method for Finding of Currents, Voltages and Termination Impedances of PCB Traces Based on Phase-less Near-field Data

The evaluation of near-field data can be an effective way to analyze EMI sources. In contrast to antenna measurements, near-field techniques can determine the emitted field without special requirements on the measurement environment. Moreover, critical sources can be found when current distributions can be identified. Therefore, current reconstruction methods for PCB traces were developed. With additional voltage information the termination impedances of the traces can be found. The known phase-less approaches suffers from different limitations, e.g., non-unique reconstruction results. In this paper, the necessary conditions for a unique reconstruction are discussed by investigating simulated phase-less near-field data. Based on these findings, measured near-field data of a PCB trace is evaluated, and the successful retrieval of the phase information is shown. Additionally, reconstructed voltage distributions are presented and compared to measurement data.