Insertion loss measurement of a ferrite clamp used in the CISPR 22 radiated emission measurements

The CISPR published an amendment to CISPR 22 for requesting ferrite clamps attached on EUT cables and specified the insertion loss of the clamps. But there are no specifications for the insertion loss measurement. Hence, theoretical and experimental investigations have been carried out to develop an appropriate measurement method with requisite measuring instruments. A 150 /spl Omega/ instrument consisting of a cylindrical rod and a ground plane is proposed. Then, the measurement uncertainty is evaluated with respect to the errors attributable to (1) the position of ferrite cores under measurement, (2) the characteristic impedance of the measuring instrument, and (3) the eccentric displacement of a ferrite core. In addition, more accurate measurements are carried out using the TRL calibration procedures.