How do I characterize a cable?

[roschiroh...@gmail.com]

Hello,

 

How do I characterize a cable for the database?

-       Reflection Stabilty (dB)

-       Transmission Stability

-       Symmetry Stability

 

 

So far, we have characterized the cable with this procedure:

 1.  We have calibrated the VNA with VNA Tools II.

2.    We have connected a Short standard at the end of test port that was mounted at the cable which we want to characterize.

3.  We have measured the Short standard.

4.    We have moved the cable from the start position to another predefined position and back.

5.    Right after the movement we have started a drift measurement with a period of 8s.

6.    We have examined the measurement after approximately 30 to 40 seconds and compared to the first measurement (Point 3.).

-    Reflection Stability (dB) = 20*log(max. deviation “S11, Mag lin”)

-    Transmission Stability (dB) = max deviation “S11, Mag lin”

 

 

Kind regards,

Simon Scherz

[Michael Wollensack METAS]

Hi Simon,

The following steps are needed to characterize the transmission stability of a cable:

1. VNA calibrated with VNA Tools
2. A short is connected to the end of the test port cable.
3. Measure S11 at several position of the test port cable.
4. Transmission Stability Mag (dB) (k=2) = Max Deviation of S11 Mag in dB / 2
5. Transmission Stability Phase (°) (k=2) = Max Deviation of S11 Phase in degree / 2

The following steps are needed to characterize the reflection stability of a cable:

1. VNA calibrated with VNA Tools
2. A load is connected to the end of the test port cable.
3. Measure S11 at several position of the test port cable.
4. Reflection Stability (dB) (k=2) = 20*log10(Max Deviation of S11 Real and Imag)

If you are using a VNA setup with test port cables and not with extender heads, you can set the 'Symmetry Stability Mag (dB)' and 'Symmetry Stability Phase (°)' to zero.

For a setup with extender heads the following steps are needed to characterize the symmetry stability:

1. VNA calibrated with VNA Tools
2. Measure a thru at several position of the test port cable.
   
3. Symmetry Stability Mag (dB) (k=2) = Max Deviation of S21/S12 Mag in dB / 2
   
4. Symmetry Stability Phase (°) (k=2) = Max Deviation of S21/S12 Phase in degree / 2

Comment: Since VNA Tools V1.8.3 Cable Transmission Stability is one-way (Ct) and not two-way (Ct*Ct).

Regards

Michael