How do I correctly enter and use the correction factors for a current probe such as the 11967A/B with an X-Series Signal Analyzer?
Current Probes such as the 11967A or 11967B are used as the transducer for many military conducted emission tests. The probe, which is clamped around the wire of interest, is exposed to the magnetic field produced by the current in the wire. The resultant output voltage of the probe is proportional to the current level, frequency, and probe characteristics such as permeability, cross-sectional area and number of turns.
To determine the current level associated with a particular voltage the transfer impedance (ZT) of the probe must be known. By subtracting the transfer impedance (dBΩ) from the voltage (dBµV) measured on the receiver the equivalent current (dBµA) can be calculated, as shown below.
Transfer Impedance (ZT) = Vout / Icond
I (dBµA) = V (dBµV) - Z (dBΩ)
The transfer impedance values for the particular current probe being used should be provided by either the manufacturer of the probe or the calibration service provider. To use these values with the X-Series Signal Analyzers you will need to enter them into the correction factors table in the analyzer.
There is one other step that needs to be taken in order to read the correct values for your measurement. As noted above, the transfer impedance correction values need to be applied to the measured dBµV values, which then become dBµA values. To do this automatically set the instrument Antenna Unit to dBµA* under the Input/Output, Corrections, Properties, Antenna Unit menu (Please note: This is not the same as setting the Y Axis Unit to dBµA).
*dBµA Antenna Unit became available with instrument software version A.11.03