172 Keysig ht N9923-90001 User’s GuideVVM (Vector Voltmeter) Mode - Option 308A/B and B/A MeasurementsA/B and B/A MeasurementsThese measurements allow you to use the FieldFox A and B receivers, alongwith an external source, to make ratioed measurements.The image below shows a typical configuration for a B/A magnitude and phasemeasurement 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 referencereceiver which measures the signal that is applied to the DUT. The B receiver isthe test port receiver which measures the DUT response.Figure 11-4 B/A Transmission measurement with external sourceProcedure1. Connect the external source’s frequency reference output to the FieldFoxFreq Ref IN on the top panel. If you are unable to use a common frequencyreference, then increase the IFBW to ensure you are measuring the peak ofthe correct signal. After locating and tuning to the signal, you may be ableto lower the IFBW to reduce noise.2. On the FieldFox, select System 7, then System Configuration, thenFrequency Ref, then Freq Ref Source then Ext.3. Press Mode, then VVM, then B/A or A/B4. For highest accuracy, set the FieldFox output power to Low. Press MeasSetup 4, then More, then Output Power Low.5. To calibrate, replace the DUT with a THRU connection, preferably byconnecting together the two Power Splitters (shown in green in thegraphic above). 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.
