On-line accuracy assessment for the dual six-port ANA: Experimental results

When a calibration laboratory such as the National Bureau of Standards (NBS) performs a measurement for a customer, the accuracy the laboratory attaches to its measurements is a significant part of the customer´s report. In some instances, the accuracy statement may be more important to the customer than the measurement itself. Modern automated measurement systems can often perform hundreds of measurements in a fraction of a second. However, few, if any, of these systems attempt to assess the accuracy of those measurements in a real-time or on-line basis. The accuracy of a modern automatic network analyzer (ANA) is a function of a number of variables. Connector quality, operator technique, system hardware, and system calibration are just a few of the many parameters that affect the day-to-day accuracy of an automated system. This paper describes the results of the current efforts at NBS to implement on-line accuracy estimates for its dual six-port network analyzers. Results are presented showing uncertainty estimates obtained in quasi-real time during the measurement of customers devices.