Approximation of High Intensity Radiated Field by Direct Current Injection using matrix methods based on Characteristic Mode Analysis

Abstract. This contribution discusses the approximation of radiated by conducted immunity tests by the example of High Intensity Radiated Field (HIRF) and Direct Current Injection (DCI) based on a surface current analysis. For this purpose, Characteristic Mode Analysis (CMA) is applied to provide basis functions for a surface current expansion in Characteristic Modes. Via a matrix-based basis transformation algorithm involving Characteristic Mode data of both HIRF and DCI test setups, suitable DCI surface currents are derived. The approximation of HIRF surface currents by the computed DCI surface currents is analyzed for exemplary DUTs over a broad frequency range. Within this frequency range, those DCI frequencies leading to an optimal approximation of the HIRF current are determined. Concerning practical issues in DCI testing, the influence of DCI adapter parameters on the surface current approximation is elucidated. The numerical results show that DCI can approximate HIRF at low frequencies largely independent from the DCI adapter setting, whereas at high frequencies an approximation is difficult to realize.