The Role of Metrology in Electromagnetic Compatibility

It is the intent of this paper to present where we, Autonetics, in specific, and the industry in general are in the EMC calibration program. Since the inception of EMC specifications, a great deal of effort has been directed toward standardizing test requirements and methods to assure compatibility, while conversely the calibration and standardization of EMI measuring instrumentation has received very little attention. The existing, and especially the most recent tri-services EMC specifications, specify accuracy requirements approaching the state of the art. A detailed analysis has shown that this accuracy specification is quite difficult to meet. In recognition of these requirements, Autonetics, A Division of North American Rockwell Corporation, has initiated a three-phase program for the calibration of EMI instrumentation. A description of measurement techniques used to perform calibration of EMI instruments is presented. The problems associated with the calibration of the Field Intensity Meter (FIM), CW Signal Generators, and Impulse Generators are reviewed. Discussions are also presented on the mismatch errors that exist between the input devices and the FIM which contribute to the overall measurement accuracy. Solutions are given to improve the calibration accuracies of EMI measuring equipment which will result in a more meaningful EMI measurement. Recommendations are given to clarify the accuracy specifications imposed by the EMC standards and specifications which can result in more realistic accuracy requirements for EMI instrumentation.