R&S ZVL
GUI Reference
Trace Menu
Operating Manual 1303.6580.32-06
196
Calculation of
J
f and
JK
With a given number of aperture steps n the delay at sweep point no. m is calculated as follows:
•
If n is even (n = 2k), then
Q
f (m) = f (m+k) – f (m–k) and
Qa
(m) =
Qa
(m+k) –
Qa
(m–k).
•
If n is odd (n = 2k+1), then
Q
f (m) = f (m+k) – f (m–k–1) and
(
m)=
Qa
(m+k) –
Qa
(m–k–1).
The delay calculation is based on the already measured sweep points and does not slow down the
measurement.
Q
f is constant over the entire sweep range, if the sweep type is a Lin. Frequency sweep. For Log.
Frequency and Segmented Frequency sweeps, it varies with the sweep point number m.
Application
The aperture must be adjusted to the conditions of the measurement. A small aperture
increases the noise in the group delay; a large aperture tends to minimize the noise effects, but at the
expense of frequency resolution. Phase perturbations which are narrower in frequency than the aperture
tend to be smeared over and can not be measured.
Remote control:
CALCulate<Chn>:GDAPerture:SCOunt
SWR
Calculates the Standing Wave Ratio (SWR) from the measured quantity (primarily: from 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
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:
