7-2 PN: 10580-00343 Rev. H S820E UG
7-2 Calibration Considerations Calibration, VNA
7-2 Calibration Considerations
Various 2-port calibrations are available in the S820E in VNA Mode.
Transmission response is the simplest and requires only one connection
during calibration, but it does not correct for test port match errors. 1-Path
2-Port calibration requires four calibration connections and corrects for the
transmit port match, but does not correct for the receive port. Full 2-port
calibration requires seven calibration connections and corrects for both test
port match errors. The full 2-port calibration technique offers the most
accuracy. Figure 7-5 on page 7-8 shows how calibration connections are
displayed by the S820E.
For accurate results, the S820E must be calibrated at the ambient
temperature after allowing for warm up time (approximately 15 minutes) and
before making any measurements. The instrument must be recalibrated
whenever the setup frequency changes, whenever the ambient temperature
changes by an amount that has more than likely rendered the calibration
invalid, or whenever a test port extension cable is added, removed, or
replaced. For an example of measurement improvement after calibration,
refer to “Example of Calibration Benefits” on page 7-4.
The calibration menu has a Thru Update submenu key (see Figure 7-12
on page 7-19) that allows you to recalibrate the Thru component without
repeating the entire calibration sequence. Refer to “Thru Update”
on page 4-16.
Calibration data are saved when you save a Setup file. When you recall a
setup, the calibration remains valid if instrument conditions (such as
temperature) remain within the calibration tolerance.
Calibration Data and Indications
When you perform a calibration, the correction coefficients are calculated for
specific S-parameters (depending on the type of calibration chosen) and for
instrument settings (frequency range, number of points, and power level).
The term “calibration correction” refers to the measurement correction
coefficients that are applied to measurements as a result of your calibration.
Note
The previously described calibration considerations omit isolation
steps in which loads are connected to each test port. During the
isolation step of the calibration procedure, the S820E (in VNA
Mode) measures the isolation between test ports in order to
achieve best dynamic range performance.
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