What VNA are using ? Are the 2 units in measurement mode ? do you know the status of each port?....

If in measurement mode the unit measuring the port of the other VNA receive the signal from the other unit and this can generate problems ,if not measuring do you know the status of the measured port is it in RX or TX ?

Ciao Gianni

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Da: [email protected] [mailto:HP-Agilent-Keysight-equipment@groups.io] Per conto di dan.meeks222@...
Inviato: mercoledì 14 settembre 2022 20:24
A: [email protected]
Oggetto: [HP-Agilent-Keysight-equipment] VNA Calibration - Port Impedance - a late life ponder

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Hello Group -
My whole life I have been calibrating VNAs and then verifying the cal by connecting Through, and looking for very good RL and IL across the band.

I'll set up my confusion / question this way: let's say I have two VNAs that are perfectly calibrated. Now I take port 1 of VNA A and connect it to port 1 of VNA B.
What I am doing is measuring VNA B's actual impedance on port 1. Which is not going to be perfect - or necessarily close to it.
The "true" impedance of any VNA port is not as good as you measure after a cal with a through.
Why is that?

After a perfect cal, with a perfect through, S11 and S22 should be showing the actual "true" impedance of the other port (port 1 is looking at Port 2, and vice-versa.

Can someone tell me what is wrong with my thinking on this? I must be wrong... but I don't know why.

Thanks in advance -
Dan