Rohde & Schwarz 1145.1010.04/05/06, Operating Manual

Page: 201 / 813

R&S
®
ZVA/ZVB/ZVT Trace Menu
1145.1084.12 4.39 E-6
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
ii
(where i denotes the port number of the DUT) according to:
The superposition of the incident and the reflected wave 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 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 envelope voltage along the line:
SWR = V
Max
/V
Min
= (|V
I
| + |V
R
|) / (|V
I
| – |V
R
|) = (1 + |S
ii
|) / (1 – |S
ii
|)
Application: Reflection measurements with conversion of the complex S-parameter to a
real SWR.
Remote control:
CALCulate<Ch->Tr>:FORMat SWR
Lin Mag
S elects a Cartesian diagram with a linear vertical axis scale to display the magnitude of the measured
quantity.
Properties: The stimulus variable appears on the horizontal axis, scaled linearly. The magnitude of the
complex quantity C, i.e. |C| = sqrt ( Re(C)
2
+ Im(C)
2
), appears on the vertical axis, also scaled linearly.
Application: Real measurement data (i.e. the Stability Factors, DC Input 1/2, and the PAE) are always
displayed in a Lin Mag diagram.
Alternative Formats
The magnitude of each complex quantity can be displayed on a logarithmic scale. It is possible to view
the real and imaginary parts instead of the magnitude and phase.
Remote control:
CALCulate<Ch->Tr>:FORMat MLINear
Real
S elects a Cartesian diagram to display the real part of a complex measured quantity.
Properties: The stimulus variable appears on the horizontal axis, scaled linearly. The real part Re(C) of
the complex quantity C = Re(C) + j Im(C), appears on the vertical axis, also scaled linearly.
Application: The real part of an impedance corresponds to its resistive portion.
Alternative Formats