A New Method to Extract Impedance between Input and Output Cables in Radiated Frequency Band of Power Converter

When the radiated CM current flows on the isolated power converters with long input-output cables, radiation will be formed in space. The coupling between the input and output cables creates the antenna effect. Based on the existing radiation noise model, accurate extraction of antenna impedance is very important to calculate the radiated CM current and predict radiation noise. This paper proposes a new antenna impedance extraction method, which comprehensively considers the coupling between the antenna and coaxial cables when measuring antenna impedance with a two-port network analyzer. The coupling is reduced to ground impedance by
$\pi$
-type model, thus improving the accuracy. To verify the correctness of the proposed method, Ansys HFSS is used for simulation comparison, and the final simulation results are in good agreement with the measured results.