Specify Offset Menu - Agilent Technologies 8719D User Manual

calibration, the analyzer will prompt for several load positions, and calculate the ideal load
value from it.
Any standard type can be further defined with offsets in delay, loss, and standard impedance;
assigned minimum or maximum frequencies over which the standard applies; and defined as
(described next).
the analyzer can prompt the user with explicit standard labels during calibration (such as
SHORT). The function is similar to defining a display title, except that the label is limited to ten
characters

Specify offset menu

The specify offset menu allows additional specifications for a user-dellned standard. Features
specified in this menu are common to alI five types of standards.
Offsets may be specified with any standard type. This means defining a uniform length of
transmission line to exist between the standard being defined and the actual measurement
plane. (Example: a waveguide short circuit terminator, offset by a short length of waveguide.)
For reflection standards, the offset is assumed to be between the measurement plane and the
standard (one-way only). For transmission standards, the offset is assumed to exist between the
two reference planes (in effect, the offset is the thru). Three characteristics of the offset can
be dellned: its delay (length), loss, and impedance.
In addition, the frequency range over which a particular standard is valid can be defined with
a minimum and maximum frequency. This is particularly important for a waveguide standard,
since its behavior changes rapidly beyond its cutoff frequency. Note that several band-limited
standards can together be defined as the same "class" (see specify class menu). Then, if a
measurement calibration is performed over a frequency range exceeding a single standard,
additional standards can be used for each portion of the range.
Lastly, the standard must be defined as either coaxial or waveguide. If it is waveguide,
dispersion effects are calculated automatically and included in the standard model.
The following is a description of the softkeys located within the specify offset menu:
. .._ , , . , . . , . , . _ . . , . ; , . , , . . .
. ~~~~~~~ allows you to specify the one-way electrical delay from the measurement
(reference) plane to the standard, in seconds (s). (In a transmission standard, offset delay is
the delay from plane to plane.) Delay can be calculated from the precise physical length of
the offset, the permittivity constant of the medium, and the speed of light.
In coax, group delay is considered constant. In waveguide, however, group delay is
dispersive, that is, it changes significantly as a function of frequency. Hence, for a waveguide
standard, offset delay must be dellned at an inllnitely high frequency.
Application and Operation Concepts
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