Agilent Sensitivity Analysis of One-port Characterized Devices in Vector Network Analyzer Calibrations 5991- free download

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Keysight Technologies Sensitivity Analysis of One-port Characterized Devices in Vector Network Analyzer Calibrations: Theory and Computational Analysis White Paper Abstract In this paper we present the results of a study on the use of characterized devices in microwave vector network analyzer (VNA) calibrations and measurements. We give a brief review of the theory of one-port character- ized device calibration. One-port characterized devices such as coaxial opens, shorts and loads are attractive because of their ease of handling and their ruggedness as compared to more fragile devices like sliding loads. The scattering parameter error box representation and widely used terminology of error terms in one-port VNA calibrations such as directiv- ity, source match and tracking are adopted in this paper. Based on these parameters, we examine the quality of one class of one-port VNA calibra- tions achievable through the use of characterized devices and the effects of different kinds of errors in device characterization can have on VNA calibrations. Computational analysis has revealed interesting properties of this class of calibrations that can lead to significant improvements in the accuracy of VNA measurements. Introduction Error correction techniques in two-port environment have been proposed [1,2] and used in industry for some time. In a model where the non-ideal behavior of a Vector Network Analyzer (VNA) is assumed to be separable from its ideal characteristics, it is widely accepted that a VNA can be described as a cascade of ideal reflectometers and error boxes. The error boxes are subsequently modeled by the theory of scatter- ing parameters. This is a much simplified picture compared to the complexity of the architecture of modern VNAs. However, this simple model has been very successful in explaining the error correction mechanism of a VNA. The procedure of characterizing the error boxes through the use of known devices is called network analyzer calibration. In a VNA configuration where there is only one port to be calibrated, as shown in Figure 1, the normalized components of this error box are known as directivity (D), source match (M) and tracking (T). These are three of the four 2-port S parameters of an error box, the fourth parameter has been nor- malized to unity. Gm is the reflection coefficient of the device under test modified by the error box. The test port reference plane P in Figure 1 is the plane separating the device under test and the test port of the VNA. Although we also assigned a second reference plane Q to the second port of the 2-port error box, this reference plane is only fictitious just as the 2-port error box itself. Speaker/Author: Godfrey Kwan Keysight Technologies 2002 NCSL International Workshop & Symposium In practice, one may determine the quantities D, M