6-45
Calibrating for Increased Measurement Accuracy
Calibrating for Noninsertable Devices
Verify the Results Since the effect of the adapter has been removed, it is easy to verify the accuracy of the
technique by simply measuring the adapter itself. Because the adapter was used during
the creation of the two cal sets, and the technique removes its effects, measurement of the
adapter itself should show the S-parameters.
If unexpected phase variations are observed, this indicates that the electrical delay of the
adapter was not specified within a quarter wavelength over the frequency range of
interest. To correct this, recall both cal sets, since the data was previously stored to disk,
change the adapter delay, and press .
Your analyzer’s programmer’s guide contains an example program that demonstrates the
adapter removal process over GPIB.
Matched Adapters With this method, you use two precision matched adapters which are "equal." To be equal,
the adapters must have the same match, Z0, insertion loss, and electrical delay. The
adapters in most Agilent calibration kits have matched electrical length, even if the
physical lengths appear different.
Figure 6 -18 Calibrating for Noninsertable Devices
To use this method, refer to Figure 6-18 and perform the following steps:
1. Perform a transmission calibr at io n u sin g the first adapter.
2. Remove adapter A, and place adapter B on port 2. Adapter B becomes the effective test
port.
3. Perform a reflection calibration.
4. Measure the test device with adapter B in place.
The errors remaining after calibration with this method are equal to the differences
between the two adapters that are used.
REMOVE ADAPTER