Agilent Technologies 8719ES User Manual page 418

Operating Concepts
Measurement Calibration
As in the reflection model, source match can cause the incident signal to vary as a function
of test device S . Also, since the test setup transmission return port is never exactly the
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characteristic impedance, some of the transmitted signal is reflected from the test set
port 2, and from other mismatches between the test device output and the receiver input,
to return to the test device. A portion of this signal may be re-reflected at port 2, thus
affecting S , or part may be transmitted through the device in the reverse direction to
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appear at port 1, thus affecting S
phase of the transmitted signal to vary as a function of S
Figure 7-36.
Figure 7-36 Load Match E
The measured value, S
relationship between E
reflection coefficients of the test device must be measured and stored for use in the S
error-correction computation. Thus, the test setup is calibrated as described for reflection
to establish the directivity, E
E , terms for reflection measurements on both ports.
RF
Now that a calibrated port is available for reflection measurements, the thru is connected
and load match, E , is determined by measuring the reflection coefficient of the thru
LF
connection.
Transmission signal path frequency response is then measured with the thru connected.
The data is corrected for source and load match effects, then stored as transmission
frequency response, E
7-48
. This error term, which causes the magnitude and
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LF
, consists of signal components that vary as a function of the
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and S as well as E
SF 11A
, source match, E
DF
.
TF
, is called load match, E
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and S , so the input and output
LF 22A
, and reflection frequency response,
SF
. See
LF
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