Calibrating An External Coupler Or External Bridge Measurement - Omicron Lab Bode 100 User Manual

8.3.2 Calibrating an External Coupler or External Bridge
measurement
In this section you learn how to calibrate an Impedance, Reflection or Admittance measurement in the
External Coupler measurement mode or in the External Bridge impedance measurement mode.
In the External Coupler measurement mode and the External Bridge impedance measurement
mode both receivers are connected to the input Channel 1 and Channel 2. Therefore all three ports of
Bode 100 must be used in these measurement modes.
A directional coupler or a resistive measurement bridge is never ideal and therefore introduces errors
caused by e.g. the frequency response of the coupler or bridge. By using Open, Short and Load
calibration, a Reference plane at the output of the coupler or bridge can be established such that all
frequency dependencies of the coupler or bridge are compensated. In the following example we show
how to remove an external measurement bridge by performing Open, Short and Load calibration at
the measurement port of the bridge. The same method can be applied to a directional coupler having
forward and reflected ports.
The External Coupler measurement mode as well as the External Bridge measurement
mode require an impedance calibration. You cannot start a measurement without having
performed Open, Short and Load calibration.
Figure 8-5: Removing a coupler / bridge by performing Open, Short and Load Calibration
80 OMICRON Lab