8-2 PN: 10580-00343 Rev. H S820E UG
8-2 How the VVM Function Works Vector Voltmeter
8-2 How the VVM Function Works
Four basic vector voltmeter measurement types are available: Reflection,
Transmission, A/B (Port 1/Port 2), and B/A (Port 2/Port 1).
With Option 441 in the S820E, you can measure relative magnitude and
phase of a DUT either directly (using the built-in source and couplers) or as a
ratio function (A/B or B/A) using appropriate external accessories such as a
CW signal source and either a power splitter or a coupler. Direct
measurements can be 1-port (reflection) or 2-port (transmission) and may
also be vector error corrected, thereby providing absolute measured values
versus relative measured values. Option 441 is a stand-alone option in the
S820E and does not require the VNA Mode (Option 440) to provide full A/B
and B/A ratio capability. All measurements made with Option 441 are based
on CW signals. They are not swept frequency measurements.
Reflection measurement (1-port): This technique is most often used for cable
trimming, but it can also be used to validate the proper electrical length of
any low loss DUT. It is most often used with a reference measurement
(golden DUT) which is stored into memory, then subsequent DUTs may be
measured and compared against the stored reference. As an option, the
measurement port may be vector error corrected (via the calibration process,
refer to Chapter 4) to provide optimal results. This is the simplest and most
convenient VVM measurement. Best results are obtained when the DUT loss
is < 20 dB. For a very lossy DUT, use the Transmission Measurement type.
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