Agilent Technologies 8753ET User Manual page 412

Operating Concepts
Measurement Calibration
Figure 7-27 Source Match E
Frequency response (tracking) error is caused by variations in magnitude and phase flatness versus
frequency between the test and reference signal paths. These are due mainly to coupler roll off, imperfectly
matched samplers, and differences in length and loss between the incident and test signal paths. The vector
sum of these variations is the reflection signal path tracking error, E
Figure 7-28 Reflection Tracking E
These three errors are mathematically related to the actual data, S
following equation:



 S
11A
S = E + ---------------------------------------
11M DF

1
–


If the value of these three "E" errors and the measured test device response were known for each
frequency, this equation could be solved for S
these errors changes with frequency, their values must be known at each test frequency. These values are
found by measuring the system at the measurement plane using three independent standards whose S
7- 44
SF
RF

E 
RF


E S 
SF 11A
to obtain the actual test device response. Because each of
11A
as shown in Figure 7-28.
RF
, and measured data, S
11A
, by the
11M
is
11A