5 CALIBRATION AND CALIBRATION KIT
Table 5.1 Systematic error terms
Port 1 Port 2
Directivity Ed1 Ed2
Source match Es1 Es2,
Reflection tracking Er1 Er2
Transmission tracking Et1 Et2
Load match El1 El2
Isolation Ex1 Ex2
After determination of all the twelve error terms for each measurement frequency by
means of a 2-port calibration, it is possible to calculate the true value of the S-
parameters: S11a, S21a, S12a, S22a.
There are simplified methods, which eliminate the effect of only one or several out of
the twelve systematic error terms.
Note If you use a 2-port calibration, to determine any of S-
parameters you need to know all the four measurements
11m, S21m, S12m, S22m. That is why to update one or all of
the S-parameters, you need to perform two sweeps: with
port 1 as a signal source, and with port 2 as a signal
5.1.4 Analyzer Test Ports Defining
The test ports of the Analyzer are defined by means of calibration. The test port is a
connector accepting a calibration standard in the process of calibration.
A type-N 50 Ω connector on the front panel of the Analyzer will be the test port if the
calibration standards are connected directly to it.
Sometimes it is necessary to connect coaxial cable and/or adapter to the connector on
the front panel for connection of the DUT with a different connector type. In such cases
connect calibration standards to the connector of the cable or adapter.
Figure 5.3 represents two cases of test port defining for 2-port measurement. The use of
cables and/or adapters does not affect the measurement results if they were integrated
into the process of calibration.