开云体育

On Wed, 8 Jan 2020 at 05:51, Gabriel Tenma White <OwOwOwOwO123@...>
wrote:

Test setup: a slightly higher end VNA was used ;) and set to 10 frequency
points, 50x averaging (so that values are noise free but still updates fast
enough). The pk-pk phase jitter observed after calibration was less than
0.1 degree. The cable under test is then connected to port 1 of the VNA,
and the other end of the cable is left open. I then bend the cable randomly
for 1 minute while keeping to a turn radius limit of 5cm, and record
maximum and minimum observed phase. The resulting (max - min) phase error
is then divided by two (because we are measuring reflection, and signals
travel up and back for 2x phase effect).
The numbers shown below are pk-pk transmission phase variation during the
bend test.

It's good to see some quantitative measurements made, but I believe the
test procedure could be improved.

Essentially it is irrelevant what the peak phase changes are when the
cables are in motion. What is important is what phase changes occur after
they have been moved. I find cables take about 30 seconds to settle back.
So my method would be to make a connection, wait 30 seconds, make another
measurement, wait another 30 seconds etc. Of course, it takes more time,
but is more representative of what one would do in a lab, and should give
better results.

Dave