Measuring Output VSWR For An Active Levelled Source

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Measuring Output VSWR For An Active Levelled Source (258.36 KB)

Mismatch error is one of the major contributions to measurement uncertainty in RF & Microwave calibration. When a signal source is used in calibration applications, knowledge of the output impedance (or source VSWR) is necessary to enable users to estimate the mismatch uncertainty contribution when performing their measurement uncertainty calculations. However, measuring the output match of an active levelled source can be difficult. The measurement techniques generally used for passive components cannot be used for active levelled sources. If those methods are used, they are likely to give erroneous misleading results. This paper discusses the output VSWR measurement method chosen for use in manufacturing test and calibrations systems for a new RF & Microwave source instrument. It also describes the steps taken to validate results by comparisons with other methods less well-suited for automation and production line usage.