VNA and LCR: two instruments, one question

[lab-lab]

Hi to all,

I'm a newbie of the microwave world....
I would like to know some more details on the use of "port extension".

With regards to the VNA....let us assume that I'm using the XXXX cable and that I have calibrated at the device port..... do I still have to perform "port extension" adjustment?... Is it necessary even when I have calibrated?!

As for the LCR meter, I noticed that it always require to select the length of the cable. ALso in this case, is it really necessary even after performing SOL calibration?

Thanks in advance for taking the time to answer to these questions.

 

[Darkcrusher]

Hi!

If you want to measure your device under test (DUT) only and are measuring it with a cable which was not present in the calibration, you should use port extension or either recalibrate with the attached cable to your DUT.

Doing so prevents faulty measurements caused by measuring both the DUT and cable

Hope this helps!

 

[lab-lab]

Thanks for the answer.
So, if I calibrate at the DUT port, after the cable has already been connected... then I do not need port extension? ... rigth?!?!

As for the LCR, however, i noticed that it always asks me the length of the cable that i'm using... even after I have performed calibration. How come?

 

[Darkcrusher]

yup thats right.

concerning your LCR meter, I dont know why. Maybe try 2 different lengths to see if your measurement is affected by this and only then bother ?