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Study Evaluates Measurement Uncertainty In VNAs And TDRs

In a recent study, measurement uncertainty was compared between vector network analyzers (VNAs) and time-domain reflectometers (TDRs). While both instruments are able to analyze time- or frequency-domain data to accelerate product development cycles, W. L. Gore & Associates Inc. (Gore) designed an experiment to determine if both instruments possess similar levels of measurement precision. Using a variety of manufacturers' cable assemblies with a range of insertionloss and VSWR characteristics, Gore performed a series of experiments. Initially, it tested six cable assemblies in controlled conditions on each instrument. Next, the firm evaluated the instruments' measurement uncertainty in the best-case scenario with the highest-performing assembly. To ensure TDR/VNA test parity, it then evaluated the VNA using both one-port S11 reflection and the more traditional two-port S21 transmission methods. According to Paul Pino, W. L. Gore & Associates' North American Product Engineer for Test and Measurement, "While the topic of measurement is a popular one and fundamental to the test and measurement industry, measurement uncertainty and accuracy are often ignored. Because precision is crucial in this industry, understanding the accuracy of an instrument is essential. Although our study indicated that one platform operated with significantly lower measurement uncertainty than the other, the important learning from this study is that both instruments are formidable tools, with each having its own strengths and weaknesses." For more details, visit gore. com/measurement to review Gore's white paper, "A Comparison of Measurement Uncertainty in Vector Network Analyzers and Time Domain Reflectometers."

W. L. Gore & Associates, Inc., 385 Starr Rd., Landenberg, PA 19350-9221; (302) 292-5100, FAX: (800) 757-4673, Internet:

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