Keysight N9927-90001 User’s Guide                                                            497
VVM (Vector Voltmeter) Mode - Option 308
A/B and B/A Measurements
A/B and B/A Measurements
These measurements allow you to use the FieldFox A and B receivers, along 
with an external source, to make ratioed measurements. 
The image below shows a typical configuration for a B/A magnitude and phase 
measurement of a 2-port DUT. This DUT can be an antenna / probe setup. 
Using network analyzer terms, the image shows the A receiver as the reference 
receiver which measures the signal that is applied to the DUT. The B receiver is 
the test port receiver which measures the DUT response. 
Figure 23-4  B/A Transmission measurement with external source
Procedure 
1. Connect the external source’s frequency reference output to the FieldFox 
Freq Ref IN on the top panel. If you are unable to use a common frequency 
reference, then increase the IFBW to ensure you are measuring the peak of 
the correct signal. After locating and tuning to the signal, you may be able 
to lower the IFBW to reduce noise.
2. On the FieldFox, select System 7
, then System Configuration, then 
Frequency Ref
, then Freq Ref Source then Ext.
3. Press Mode
, then VVM, then B/A or A/B
4. The FieldFox internal source is NOT used, so the output power setting is 
not relevant. 
5. To calibrate, replace the DUT with a THRU connection, preferably by 
connecting together the two Power Splitters (shown in green). For low 
frequency measurements, TEEs can be used. 
6. Press Meas Setup 4
, then Zero.
7. Connect the DUT and measure.
These measurements require the “Full 2-port S-parameters” option.