Calibration Standards

The quality of the error-correction is limited by two factors: (1) the difference between the model of the calibration standards and the actual electrical characteristics of those standards, and (2) the condition of the calibration standards. lb make the highest quality measurement calibration, follow the suggestions below:

H Use the correct standard model.

nInspect the calibration standards

nClean the calibration standards, H Gauge the calibration standards.

nUse correct connection techniques.

If you want to use calibration standards other than the default sets, you must change the standard model. (Refer to “Modifying Calibration Kit Standards” located later in this chapter.) After you enter the mathematical model for the new calibration standards, the analyzer can then use the model that corresponds to the new standards

Compensating for the Electrical Delay of calibration Standards

Short and open calibration standards in the 3.5~mm, 2.4~mm, and 2.92~mm connector types have a certain amount of electrical delay. The analyzer compensates for this delay by offsetting the calibration results by the total amount of electrical delay caused by the calibration standard in both the forward and reverse direction. As a result, if these standards are measured after a calibration, they will not appear to be “perfect” shorts or opens. This is an indication that gour UTZ.@J~ is working proper& and that it has successfully performed a calibration.

Note If you enter the opposite amount of electrical delay that was used by the analyzer during calibration, then the short calibration standard will appear to be “perfect.” The open calibration standard has additional phase shift caused by fringing capacitance. See “Calibration Considerations” in Chapter 6, “Application and Operation Concepts n

Chrifyhg We-N Connector Sex

When you are performing error-correction for a system that has type-N test port connectors,

the softkey menus label the sex of the test port connector--not the calibration standard coMe~or. For example, the label ~~~~~~~~~~ refers to the shod that fl be coMe&ed to the

female test port.

When to Use Interpolated Error-Correction

You may want to use interpolated error-correction when you choose a subset of a frequency range that you already corrected, when you change the number of points, or when you change to CW. This feature also allows you to change the parameters in a 2-port correction, such as IF bandwidth, power, or sweep time. The analyzer calculates the systematic errors from the errors of the original correction.

The quality of the interpolated error-correction depends on the amount of phase shift and amplitude change of the error coefficients between measurement points If the phase shift is cl800 per five measurement points, the interpolated error-correction can be a great improvement over uncorrected measurement.

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‘l’b a&iv&e interpolated measurement cofle&ion, press a ~~~~~~ ~~~~~~.~~~~1.

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