Difference between measured S12 and S12 of a Passive circuit

Hi Guys,

I see a strange phenomena in our E8358A VNA having S12 and S21 abit different (around 0.2 dB and 2 deg.). Although I use a standard calibration kit to calibrate, the cables I used are RG142U which are not very stable. Can it be due to this problem or you have another idea?

cheers,
Hadi

It's normal, 0.2dB and 2 degrees are all in VNA accuracy.

100% agree...
it`s key word.

Do you have any solution to reduce this difference?

Stable cables, add attenuators ~10dB to the end of the cables and calibrate together. And good calibration kit and accurate and fine work.