Rohde & Schwarz ZNB20, Руководство пользователя

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Concepts and Features
R&S
®
ZNB/ZNBT
204 User Manual 1173.9163.02 ─ 38
4.7.3.1 Calibration Options
In arbitrary mode, the R&S ZNB/ZNBT automatically calibrates the source and receive
frequency ranges of all ports, according to the frequency conversion settings in the
"Port Settings" dialog or in the dedicated configuration dialogs ("Mixer Meas", "Intermo-
dulation Wizard").
●
The SMARTerCal is the recommended calibration method for frequency conver-
sion measurements.
●
For measurements on non-linear DUTs, an additional scalar power calibration is
recommended; for details refer to
Chapter 4.5.7, "SMARTerCal" , on page 172.
●
A load match correction (optional) involves an additional reverse sweep. It can pro-
vide a significant improvement of the transmission S-parameter measurements if
the load ports are poorly matched.
Select the appropriate correction type according to your accuracy and speed require-
ments. Notice that none of the correction types provides the phase information for
transmission S-parameters.
4.7.3.2 Scalar Mixer Measurements
Scalar Mixer measurements are included in option R&S ZNB/ZNBT-K4.
RF mixers convert an RF signal at one frequency into a signal at another frequency.
The frequency that is to be shifted is applied at the RF input and the frequency shifting
signal (from a local oscillator, LO) is applied to the RF mixer's LO port, resulting in an
output signal at the mixer's Intermediate Frequency (IF) port. For a given RF signal, an
ideal mixer would produce only two IF outputs: one at the frequency sum of the RF and
LO (IF = RF + LO), and another at the frequency difference between the RF and LO (IF
= |RF – LO|). Filtering can be used to select one of these IF outputs and reject the
unwanted one.
Meaning of S-parameters
The frequency-converting property of the mixer (i.e. the fact that incident and transmit-
ted waves are at different frequencies) causes a loss of phase information. While a
scalar measurement is active, the reverse transmission parameter S
12
is unavailable;
the magnitude of the forward transmission parameter S
21
describes the conversion
gain. The conversion gain measurement can be improved by a source match (included
in the SMARTerCal) and load match correction (optional). The phase information,
including the group delay, is meaningless.
In the scalar mixer mode the analyzer provides the following functionality:
●
Configuration of the RF and LO signals and measurement of the generated IF sig-
nal.
●
System error correction and power calibration of the signal sources and of the IF
receiver. A SMARTerCal is recommended for this purpose; see
Chapter 4.7.3.1,
"Calibration Options" , on page 204.
Optional Extensions and Accessories