Concepts and Features
R&S
®
ZNA
205
User Manual 1178.6462.02 ─ 12
Intermodulation Quantities
A nonlinear DUT that is supplied with a two-tone signal with the lower/upper frequen-
cies f
L
and f
U
causes emissions at frequencies which correspond to sums and differen-
ces of the upper and lower tone frequencies and their integer multiples:
f
U
– f
L
, f
U
+ f
L
, 2*f
U
– f
L
, 2*f
U
+ f
L
, f
U
+ 2*f
L
, 2*f
L
– f
U
...
The order of these intermodulation products is defined by the number of f
L
and f
U
terms. The analyzer measures the intermodulation products of k
th
order IMk (where 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
n
).
The intermodulation suppression IMk
rel
is the ratio of the power of an intermodulation
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
out
is defined as follows:
IPk
out
= P
L, out
+ IMk
rel
/ (k – 1)
In this formula, P
L, out
denotes the lower tone power in dBm, measured at the DUT out-
put. In analogy, the input intercept point IPk
in
is defined as:
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