R&S ZVL
GUI Reference
Trace Menu
Operating Manual 1303.6580.32-06
194
Smith
S
elects a Smith chart to display a complex quantity, primarily a reflection S-parameter.
Properties:
The Smith chart is a circular diagram obtained by mapping the positive complex semi-plane
into a unit circle. Points with the same resistance are located on circles, points with the same reactance
produce arcs. If the measured quantity is a complex reflection coefficient (S
11
, S
22
etc.), then the unit
Smith chart represents the normalized impedance. In contrast to the polar diagram, the scaling of the
diagram is not linear.
Application:
Reflection measurements, see application example.
The axis for the sweep variable is lost in Smith charts but the marker functions easily provide the
stimulus value of any measurement point. dB values for the magnitude and other conversions can be
obtained by means of the
Marker Format
functions.
Remote control:
CALCulate<Chn>:FORMat SMITh
Polar
Selects a polar diagram to display a complex quantity, primarily an S-parameter or ratio.
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 application example.
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 magnitude and other conversions can be
obtained by means of the
Marker Format
functions.
Remote control:
CALCulate<Chn>:FORMat POLar
Group Delay
Calculates the (group) delay from the measured quantity (primarily: from a transmission S-parameter) and
displays it in a Cartesian diagram.
Properties:
The group delay
`
g
represents the propagation time of wave through a device.
`
g
is a real
quantity and is calculated as the negative of the derivative of its phase response. A non-dispersive DUT
shows a linear phase response, which produces a constant delay (a constant ratio of phase difference to
frequency difference).
Mathematical relations: Delay, Aperture, Electrical Length
The group delay is defined as:
where
X
rad/deg
= Phase response in radians or degrees
