S-Parameters Characterization for EMI Filters: Limitations

This paper describes the S-parameters measurement techniques for electromagnetic interference filter performance evaluation using single-ended to mixed-mode conversion and pure-mode approaches In conjunction with an SDR-based vector network analyzer, it investigates the feasibility and accuracy of these techniques. Experimental results from testing commercial off-the-shelf filters and custom-made notch filters are presented, demonstrating the capabilities and limitations of used measurement techniques, and highlighting the influence of VNA parameters on measurement accuracy and the trade-off between speed and precision of the measurement results.