Agilent Technologies 8753ET User Manual page 442

Operating Concepts
TRL*/LRM* Calibration (ES Models Only)
TRL Options
The
TRL/LRM OPTION
this menu:
• (calibration Z
CAL ZO:
• (set reference)
SET REF:
The characteristic impedance used during the calibration can be referenced to either the line (or match)
standard (
CAL ZO: LINE ZO
calibration impedance that is equal to the line (or match) standard.
When the
CAL ZO: LINE ZO
match the system impedance exactly (the line standard is reflectionless). After a calibration, all
measurements are referenced to the impedance of the line standard. For example, when the line standard is
remeasured, the response will appear at the center of the Smith chart. When
selected, the values entered for
standard menu) are ignored.
CAL ZO: SYSTEM ZO
impedance of the line standard. This requires a knowledge of the exact value of the Z
system reference impedance is set using
the line is set by entering the real part of the line impedance as the
standard menu. For example, if the line was known to have a characteristic impedance of 51 
= 51 ) , it could still be used to calibrate for a 50  measurement (
(
OFFSET ZO
After a calibration, all measurements would be referenced to 50  , instead of 51  . When the line standard
is remeasured, the center of the Smith chart is at the current value of
only one value of offset Z
over the frequency range of interest in order to be meaningful.
The location of the reference plane is determined by the selection of
SET REF: REFLECT
known insertion phase or electrical length. If a non-zero length thru is specified to have zero delay, the
reference plane will be established in the middle of the thru. The reflect standard may be used to set the
reference plane instead of the thru provided the phase response (offset delay, reactance values and
standard type) of the reflect standard is known and is specified in the calibration kit definition.
7- 74
softkey accesses the TRL/LRM options menu. There are two selections under
)
0
) or to the system (
is selected, the impedance of the line (or match) standard is assumed to
(under
SET ZO
is selected when the desired measurement impedance differs from the
SET ZO
can be selected for the line standard, the value of Z
0
. By default, the reference plane is set with the thru standard which must have a
CAL ZO: SYSTEM ZO
menu) and
OFFSET ZO
Cal
under the calibration menu. The actual impedance of
OFFSET ZO
SET ZO
SET REF: THRU
). The analyzer defaults to a
is
CAL ZO: LINE ZO
(within the define
of the line. The
0
within the define
= 50 ) .
SET ZO
(in this case, 50 ). Since
should be a constant value
0
and