One of the most frequently asked questions we receive at Copper Mountain Technologies’ sales and support departments goes something like this: “What about calibration?” It’s an unfortunate reality that in the English language, Calibration has two completely distinct definitions. The first relates to checking out the instrument periodically to make sure it is operating within its specifications. “Performance test” is the procedure by which the analyzer performance is verified, typically annually. The second meaning is to do with Measurement or User calibration, a collection of techniques by which measurement accuracy is maximized and made to exclude elements of the system from those measurements (such as cables, adapters and the like). In this application note, we discuss both meanings of calibration as related to Copper Mountain Technologies’ Vector Network Analyzers (VNAs). First, we describe Annual Calibration and then later we discuss measurement calibration.

Copper Mountain Technologies produces lab-grade VNAs with outstanding measurement accuracy. As with every VNA, performing a good calibration is necessary for maximizing the accuracy of VNA measurement results, for de-embedding the effects of imperfect cables and components in the fixture, and for moving the reference plane to the DUT interfaces. There are several approaches for determination and application of VNA measurement corrections, including port extension (a relatively crude, approximate method), fixture de-embedding (with accuracy depending on correctness of the model), and calibrating with a calibration kit (a high accuracy approach). Generally, there are two broad categories of calibration kit types: traditional mechanical kits and automatic/electronic calibration modules. Within mechanical kits, there are two types of kits: those with standard “polynomial” coefficients and those with full S-parameter characterization data, also known as databased kits. This application note introduces databased calibration kits, explains why their use is growing in popularity, and describes how they can be used with Copper Mountain Technologies VNAs.