Modifying Calibration Kits
Modifying calibration kits is necessary only if unusual standards (such as in TRL') are used
or the very highest accuracy is required. Unless a calibration kit model is provided with the
calibration devices used, a solid understanding of error-correction and the system error model
are absolutely essential to making modifications. You may use modifications to a predelined
calibration kit by modifying the kit and saving it as a user kit. The original predeflned
calibration kit will remain unchanged.
application note is 5956-4352. Although the application note is written for the HP 8510 family
of network analyzers, it also applies to the HP 8719D/20D/22D.
Several situations exist that may require a user-defined calibration kit:
kits. (Examples: SMA, TNC, or waveguide.)
default calibration kits is required. (Example: Using three offset shorts instead of open,
short, and load to perform a l-port calibration.)
Remember that the more closely the model describes the actual performance of the standard,
the better the calibration. (Example: The 7 mm load is determined to be 50.4 ohms instead
of 50.0 ohms.)
Definitions
The following are definitions of terms:
A "standard" (represented by a number 1-8) is a specific, well-defined, physical device used
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to determine systematic errors. For example, standard 1 is a short in the 3.5 mm calibration
kit. Standards are assigned to the instrument softkeys as part of a class.
A standard "type' is one of five basic types that define the form or structure of the model to
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be used with that standard (short, open, load, delay/thru, and arbitrary impedance); standard
1 is of the type short in the 3.5 mm calibration kit.
Standard "coefficients" are numerical characteristics of the standards used in the model
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selected. For example, the offset delay of the short is 32 ps in the 3.5 mm calibration kit.
A standard "class" is a grouping of one or more standards that determines which of the eight
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standards are used at each step of the calibration. For example, standard number 2 and 8
usually makes up the &IA reflection class, which for type-N calibration kits are male and
female shorts
Procedure
The following steps are used to modify or de9ne a user kit:
1. Select the predelhted kit to be modified. (This is not necessary for defining a new calibration
kit.)
2. Define the standards:
a. Define which "type" of standard it is.
b. Define the electrical characteristics (coefficients) of the standard.
3. Specify the class where the standard is to be assigned.