User`s guide

7-52
Operating Concepts
Measurement Calibration
How Effective Is Accuracy Enhancement?
In addition to the errors removed by accuracy enhancement, other systematic errors exist
due to limitations of dynamic accuracy, test set switch repeatability, and test cable
stability. These, combined with random errors, also contribute to total system
measurement uncertainty. Therefore, after accuracy enhancement procedures are
performed, residual measurement uncertainties remain.
The uncorrected performance of the analyzer is sufficient for many measurements.
However, the next three illustrations show the improvements that can be made in
measurement accuracy by using a more complete calibration routine. See Figure 7-40,
Figure 7-41, and Figure 7-42.
Figure 7-40a shows a measurement in log magnitude format with a response calibration
only. Figure 7-40b shows the improvement in the same measurement using an S11
one-port calibration. Figure 7-41a shows the measurement on a Smith chart with response
calibration only, and Figure 7-41b shows the same measurement with an S11 one-port
calibration.
Figure 7-40 Response versus S11 1-Port Calibration on Log Magnitude Format