An Efficient Probe Calibration Based Near-Field-to-Near-Field Transformation for EMI Diagnosis

The near-field scanning is an effective technology for electromagnetic interference (EMI) diagnosis. An accurate and efficient near-field-to-near-field transformation in the reactive near-field region of the EMI radiation source plays an important role in the near-field scanning. In this paper, an efficient near-field-to-near-field transformation based on the electromagnetic probe calibration is proposed. By using the plane wave spectrum expansion of the probe output, the magnetic fields under test on multiplanes are obtained through a single-plane probe scanning. The proposed transformation can be considered as the extension of the prior probe compensation/calibration methods (where the field on only one plane is derived). The proposed method is validated with both numerical and experimental examples. A good agreement between the results of the proposed method and the full-wave simulation is achieved. In comparison with prior probe calibration methods, the proposed method does well, especially in determining the fields below the probe's scanning plane. This is deterministically useful for accurately identifying the potential radiation sources during the EMI diagnosis.