Concepts and features
R&S
®
ZNA
270User Manual 1178.6462.02 ─ 29
IPk
in
= P
L, in
– IMk
rel
/ (k – 1)
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.
4.7.3.3 Harmonics measurements
Harmonics are signals at an integer multiple of the fundamental frequency. The funda-
mental is the first harmonic, the Nth harmonic is N times the frequency of the funda-
mental. The production of harmonic frequencies by an electronic system, when a sig-
nal is applied at the input, is known as harmonic distortion.
Harmonic distortion measurements can be performed irrespective of the sweep type: A
frequency sweep yields the harmonics as a function of the frequency, a power sweep
yields the power-dependent harmonics at fixed frequency.
Apart from absolute and relative harmonic power measurements, it is also possible to
measure the total harmonic power, defined as:
Equation 4-1: Fundamental THD of order N
Equation 4-2: Root mean square THD of order N
Harmonic power calibration
Due to the different frequency ranges of the input and output signals, the harmonic
power calibration must be performed in two steps. For a test setup where the DUT's
input signal (fundamental signal) is provided by analyzer port 1 and where the har-
monic is analyzed at port 2, the following test setups are required
1. Source power calibration of the fundamental signal and the harmonic frequency
ranges
Optional extensions and accessories
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