R&S ZNB Series User Manual page 324

®
R&S ZNB/ZNBT
Properties: The polar diagram shows the measured data (response values) in the
complex plane with a horizontal real axis and a vertical imaginary axis. The magnitude
of a complex value is determined by its distance from the center, its phase is given by
the angle from the positive horizontal axis. In contrast to the Smith chart, the scaling of
the axes is linear.
Application: Reflection or transmission measurements, see example in
on page 119.
Tip: The axis for the sweep variable is lost in polar diagrams but the marker functions
easily provide the stimulus value of any measurement point. dB values for the magni-
tude and other conversions can be obtained by the "Marker Format" functions.
Remote command:
CALCulate<Chn>:FORMat
SWR
Calculates the standing wave ratio (SWR) from the measured quantity (typically a
reflection S-parameter) and displays it in a Cartesian diagram.
Properties: The SWR (or voltage standing wave ratio, VSWR) is a measure of the
power reflected at the input of the DUT. It is calculated from the magnitude of the
reflection coefficients S
SWR
The superposition of incident and reflected wave on the transmission line connecting
the analyzer and the DUT causes an interference pattern with variable envelope volt-
age. The SWR is the ratio of the maximum voltage to the minimum envelope voltage
along the line.
Interpretation of the SWR
The superposition of the incident wave I and the reflected wave R on the transmission
line connecting the analyzer and the DUT causes an interference pattern with variable
envelope voltage. The SWR is the ratio of the maximum voltage to the minimum enve-
lope voltage along the line:
SWR = V
Application: Reflection measurements with conversion of the complex S-parameter to
a real SWR.
Remote command:
CALCulate<Chn>:FORMat
Unwr Phase
Selects a Cartesian diagram with an arbitrarily scaled linear vertical axis to display the
phase of the measured quantity.
User Manual 1173.9163.02 ─ 62
POLar
(where i denotes the port number of the DUT) according to:
ii

1 | S |

ii

1 | S |
ii
/V = (|V | + |V |) / (|V
Max Min I R
SWR
| – |V |) = (1 + |S |) / (1 – |S
I R ii
GUI reference
Format softtool
"Polar"
|)
ii
324