R&S ZVL GUI Reference
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Operating Manual 1303.6580.32-06
249
The offset parameters depend on whether or not the circuit model is defined in Agilent Mode (see
Add/Modify Calibration Kit dialog):
• If Agilent Mode is active, then the standard is characterized by its Delay (in s), its characteristic
impedance Z
0
(in V) and its Offset Loss (in GV/s).
• If Agilent Mode is switched off, then the standard is characterized by the ZVR-compatible
parameters Electrical Length (in m or foot (ft), depending on the Distance Unit selected in the
System Configuration dialog), its Char. Impedance (in V) and its Loss (in dB/sqrt(GHz)). The loss
is zero and not editable as long as the electrical length is zero.
Both parameter sets are closely related. The Electrical Length is proportional to the Delay; Z
0
corresponds
to the Char. Impedance. Moreover the analyzer converts an Agilent-type Offset Loss into a ZVR-type Loss
and vice versa using the Relative Permittivity N
r
for the connector type defined in the Offset Model... dialog.
Offset parameters
The offset parameters have the following physical meaning:
• The Delay is the propagation time of a wave traveling through the standard. The Electrical Length
is equal to the Delay times the speed of light in the vacuum and is a measure for the length of
transmission line between the standard and the actual calibration plane. For a waveguide with
permittivity N
r
and mechanical length L
mech
the following relations hold:
The default delay is 0 s, the default step width is 1 ns, corresponding to a step width of 299.792 mm
for the electrical length. The relations hold for one-port and 2-port standards.
• Z
0
is the Characteristic Impedance of thestandard. If the standard is terminated with Z
0
, then its
input impedance is also equal to Z
0
. Z
0
is not necessarily equal to the reference impedance of the
system (depending on the Connector Type) or the terminal impedance of the standard. The
characteristic impedance of the standard is only used in the context of calibration.
The default characteristic impedance is equal to the reference impedance of the system.
• The Loss is the energy loss along the transmission line due to the skin effect. For resistive lines
and at RF frequencies the loss is approximately proportional to the square root of the frequency.
In Agilent mode the Offset Loss is expressed in units of V/s at a frequency of 1 GHz. The following
formula holds:
To determine an offset loss value experimentally, measure the delay in seconds and the loss in dB
at 1 GHz and use the formula above.
The default Loss or Offset Loss is zero.
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