The Investigation Of Uncertainty Sources Of Immunity To Conducted Disturbances, Induced By Radio-Frequency Fields

In the immunity measurement to conducted disturbances, induced by radio-frequency fields, the uncertainty sources of influence measurement result usually include the two important categories:the measurement instrumentation uncertainty (MIU) and the intrinsic uncertainty of the measurand. The measurement instrumentation uncertainty primarily include the measurement uncertainty that Signal generator, Power amplifier, Coupling and decoupling devices introducing. This paper mainly investigates the uncertainty of measurement that coupling and decoupling devices introducing, the same equipment is tested using the different coupling and decoupling devices (CDN, Current clamp, EM clamp). The measurement results demonstrate:For the uniform port of the same equipment, using different coupling and decoupling devices, even if other test setup is completely same, There are huge differences for the measurement result, especially in the higher frequency band,There are the differences of more than27dB among the measurement results. So variation of the coupling and decoupling devices has a great effect on measurement uncertainty. The intrinsic uncertainty of the measurand include the measurement uncertainty that measurement setup, the measurand specification and equipment level introducing, this paper mainly investigates the uncertainty that the variation of the measurement setup introducing. It takes the five possible variations of the measurement setup into account. for example, the Common mode impedance variation of the accessory equipment, the height variation of positioning the cable under the test, the distance variation between the equipment under the test and the Coupling and decoupling devices, the distance variation between the AE and the Coupling and decoupling devices, the grounding manner of the Coupling and decoupling devices etc. the measurement results demonstrate:the small variation of the measurement setup will introduce the very distinct uncertainty for the immunity to conducted disturbances, induced by radio-frequency fields, especially in the higher frequency band, There are the differences of more than20dB among the measurement results. So during immunity measurement to conducted disturbances, induced by radio-frequency fields, in order to ensure uniformity and high repeatability of test, we should control these decisive factors according to the standard.