Concepts and features
R&S
®
ZNB/ZNBT
118
User Manual 1173.9163.02 ─ 62
Figure 4-5: S11 trace in dB Mag format: sweep type Lin Freq (top) and Log Freq (bottom)
Conversion of complex to real quantities
Among the measured quantities the R&S
ZNB/ZNBT supports, only "Stability" factors,
"Power Sensor" results, and "DC" values are real. All other results measured quantities
complex.
The following table shows how "real" response values are calculated from complex
measurement values z = x + j y (where x, y, z are functions of the sweep variable). The
formulas also hold for real measurement values (y = 0).
Trace Format
Description
Formula
"dB Mag"
Magnitude of z in dB
dB Mag(z) = 20 * log|z| dB
"Phase"
Phase of z
φ (z) = arctan (y/x)
"SWR"
(Voltage) Standing Wave Ratio
SWR = (1 + |z|) / (1 – |z|)
"Lin Mag"
Magnitude of z, unconverted
|z| = sqrt ( x
2
+ y
2
)
"Real"
Real part of z
Re(z) = x
"Imag"
Imaginary part of z
Im(z) = y
"Delay"
Group delay, neg. derivative of the
phase response
– d φ (z) / dΩ (Ω = 2
π
* f)
An extended range of formats and conversion formulas is available for markers. To
convert any point on a trace, create a marker and select the appropriate marker format.
Marker and trace formats can be selected independently.
4.2.3.2
Complex trace formats
Complex trace formats assign a complex response to the stimulus value (frequency,
power, or time).
Screen elements
