VVM (Vector Voltmeter) Mode 147
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.
NOTE These measurements require the “Full 2-port S-parameters” option.
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.
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 , then System Configuration, then
Frequency Ref, then Ext.
3. Press Mode, then VVM , then B/A or A/B
4. For highest accuracy, set the FieldFox output power to Low. Press Meas
Setup 4, then More, then Output Power Low.
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.
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