Anritsu S820E - Log Magnitude; 2; Phase; Real and Imaginary

6-6 PN: 10580-00343 Rev. H S820E UG
6-3 Calculating and Displaying S-Parameters VNA Mode
Log Magnitude / 2
Applications
For measuring 1-port cable loss, use S
11
or S
22
with the Log Mag/2 display
type to account for the round trip signal path through the cable. When using
reflection data to measure cable loss, the end of the cable must be shorted or
must be a perfect open.
Phase
Applications
Use the Phase or Unwrapped Phase measurement to display the phase in
degrees of S
xy
. The Phase measurement is contained within a vertical scale of
±180_degrees, whereas the unwrapped phase displays the linear phase
without wrapping it at the 180_degrees transitions. See Figure 6-2
on page 6-8. Unwrapped phase is obtained by counting the number of
transitions of the phase measurement (note the vertical scale in the figure).
Unwrapped phase will be accurate only if the measurement has enough data
points to capture all of these transitions. Also, the first data point must be
low enough in frequency so that its phase is less than 180_degrees from DC,
otherwise the unwrapped phase measurement will have errors.
Real and Imaginary
Applications
Use the Real and Imaginary graph types to measure the elements of the
complex S-parameter S
xy
.
LogMagnitude
2
-----------------------------------
dB() 0.5 20× Log
10
S
xy
=
Phase degrees()Tan
1–
S
Imaginary
S
Real
--------------------------
180
π
---------


×=
S
Real
Real part of the complex S-parameter S
xy
=
S
Imaginary
Imaginary part of the complex S-parameter S
xy
=