Concepts and features
R&S
®
ZNA
114
User Manual 1178.6462.02 ─ 20
Diagram representation
When a Cartesian trace is assigned to a diagram, the stimulus variable appears on the
horizontal axis (x-axis), the response values appear on the vertical axis (y-axis).
Graph Scaling
●
Except for the "Log Mag" format, the y-axis scale is always linear.
●
The x-axis scaling depends on the sweep type of the channel to which the trace is
assigned:
–
For sweep types "Lin Freq", "Power", "CW Mode" and "Time" it is scaled line-
arly.
–
For sweep type "Log Freq", it is scaled logarithmically.
The resulting linear or lin-log grid is plotted with the formatted trace.
The following examples show "dB Mag" Cartesian traces for the same measured quan-
tity and sweep range, but with "Lin Freq" and "Log Freq" sweep types.
Figure 4-3: S11 trace in dB Mag format: sweep type Lin Freq (top) and Log Freq (bottom)
Conversion of complex to real quantities
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|)
Screen elements
