R&S ZNB Series User Manual page 246

®
R&S ZNB/ZNBT
Intermodulation quantities
A nonlinear DUT that is supplied with a two-tone signal with the lower/upper frequen-
cies f
ces of the upper and lower tone frequencies and their integer multiples:
f – f
U L
The order of these intermodulation products is defined by the number of f
terms. The analyzer measures the intermodulation products of k
3, 5, 7, 9) at the lower tone frequency minus (k – 1)/2 times the tone distance and at
the upper tone frequency plus (k – 1)/2 times the tone distance. Intermodulation prod-
ucts can be measured at the DUT output (transmitted wave b
The intermodulation suppression IMk
product to the power of the lower tone fundamental wave in dB, measured at the DUT
output.
For each intermodulation product, an output intercept point IPk
IPk
out
In this formula, P
put. In analogy, the input intercept point IPk
IPk
in
The intermodulation suppression generally decreases with increasing stimulus power.
The intercept point is equal to the lower tone power for which the intermodulation sup-
pression would reach 0 dB. Output and input intercept point differ by the attenuation of
the lower tone signal upon transmission through the DUT. The intercept point is a
mathematical concept. For most DUTs, it is beyond the nominal power operating
range.
Filter settings
Intermodulation measurements require frequency-selective filter settings. When an
intermodulation result is selected, the analyzer checks whether the IF bandwidth of the
active channel is 1/100 of the distance between the upper and the lower tone ("Tone
Distance") or less. If not, the analyzer displays a tooltip.
Selectivity is automatically set to high, but can be changed manually.
4.7.5 Receiver bandwidth 10 MHz
Option R&S ZNB/ZNBT-K17
This software option increases the maximum receiver bandwidth of a R&S ZNB/ZNBT
from 1 MHz to 10 MHz.
User Manual 1173.9163.02 ─ 62
and f causes emissions at frequencies which correspond to sums and differen-
L U
, f + f , 2*f – f , 2*f + f
U L U L U
= P + IMk / (k – 1)
L, out rel
denotes the lower tone power in dBm, measured at the DUT out-
L, out
= P + IMk / (k – 1)
L, in rel
Optional extensions and accessories
, f + 2*f , 2*f – f ...
L U L L U
is the ratio of the power of an intermodulation
rel
is defined as:
in
Concepts and features
and f
L U
th
order IMk (where k =
).
n
is defined as follows:
out
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