VNA Concepts and Features
R&S
®
ZNL/ZNLE
248
User Manual 1178.5966.02 ─ 07
Standard Type
Characteristics
Ideal Standard
Offset Model Load Model
Sliding match
One-port standard consisting of an air line with a
movable, low-reflection load element (sliding load)
–
–
–
Reflect
Unknown mismatched standard (one-port)
∞
Ω
☑
☑
Through
Through-connection with minimum loss (two-port)
–
☑
–
Line1, Line 2
Line(s) for TRL calibration with minimum loss (two-
port)
–
☑
–
Attenuation
Fully matched standard in both directions (two-
port; the reflection factor at both ports is zero)
–
–
–
Symm. network
Unknown mismatched reflection-symmetric stan-
dard (two-port)
–
☑
☑
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. It is a
measure for the length of transmission line between the standard and the actual
calibration plane. For a waveguide with permittivity ε
r
and mechanical length L
mech
,
the following relations hold:
r
mech
r
mech
L
c
L
Length
Electrical
;
Delay
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 the standard. 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 Ω/s at a frequency of 1
GHz. The following formula holds for two-port standards:
s
delay
dB
Z
dB
Loss
s
Loss
Offset
/
/
3429
.
4
/
/
/
/
0
The conversion formula for one-port standards has an additional factor ½ on the
right-hand side. The reason for this factor is that the Loss in dB accounts for the
attenuation along the forward
and
the reverse path. It does not depend on how
Calibration
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Allice Messtechnik GmbH
