Concepts and features
R&S
®
ZNB/ZNBT
239
User Manual 1173.9163.02 ─ 62
Two-stage mixer measurements
The scalar mixer measurement is also suited for measuring a system of two mixers
with frequency multipliers at their RF and LO inputs. The RF and LO input frequencies
of the first mixer are both multiplied by an integer fraction; the converted output signal
f
int
is fed to the second mixer, together with the multiplied second LO signal. The ana-
lyzer measures the output signal of the second mixer at its IF input port. The general
test setup is shown below; the mixer system under test (MUT) is enclosed in a blue
rectangle.
The figure above also shows the possible output frequencies of the two mixers. The
actual values of f
int
and f
IF
depend on the RF and LO frequencies and of the measured
conversion (lower sideband or upper sideband with up- or down-conversion). The ana-
lyzer automatically calculates all frequencies and sets its receiver according to the set-
tings made.
A test setup with two mixers requires 3 independent source ports plus one receive port.
A R&S
ZNB/ZNBT with two internal sources (see
Chapter 4.7.14, "Internal second
on page 255) requires one external generator, all other R&S
ZNB require two
external generators.
A standard mixer measurement with a single mixer stage and no frequency multipliers
corresponds to the figure above with the second mixer and LO 2 omitted and m
1
= n
1
=
m
2
= n
2
= 1.
Mixer diagrams
The mixer signal diagrams show the parameters of the mixer input signals (RF, LO)
and of the mixing product (IF signal, output).
●
The RF signal is the stimulus signal that the analyzer generates with the current
channel settings. After a reset, the frequency and power of the RF signal is as
defined in the Channel – Stimulus menu. The RF signal parameters can be
changed in the "Power" and "Frequencies" dialogs.
●
The Local Oscillator (LO) signal is an additional RF signal that is either generated
by the network analyzer (at one of the ports that are not used for the RF and IF
Optional extensions and accessories
