doi: 10.6028/NIST.TN.1333

Robert T. Adair and Eleanor M. Livingston

Abstract:

This paper discusses how impedance standards are derived from basic definition of impedance, constructed and used in metrology with coaxial air-line systems. Basic transmission line equations are reviewed with emphasis given to intrinsic or derived standards for obtaining the impedance in low-loss transmission line systems. A brief description is given of how impedance standards are used to calibrate the vector automatic network analyzer, and specifically, the six-port system automatic network analyzer used at the National Institute of Standards and Technology for calibration services in the radio frequency, microwave, and millimeter wave areas. Measurement uncertainties are given for 7 mm coaxial devices measured with the National Institute of Standards and Technology six-port system. The resolution of our six-port system is several orders more precise than that of the present impedance standards from which it is calibrated. Required improvements in the physical dimensions of air-line standards which permit the automatic network analyzer’s capability to be more fully utilized are given.

Keywords: radio frequency; standards; microwave; coaxial cable; impedance

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