how to measure impedance using VNA

Hi,

is it possible to measure LCR measurements using normal vector network analyzer (by calculating),
and how it relate impedance(smith or real formats) on VNA with passive components.

thank you.

Basically yes, I'm doing this quite often. The shunt impedance (RL or RC equivalent circuit) is usually already displayed in a single-port measurement. But the useful impedance range is restricted by the 50 ohm characteristic port impedance. A wider impedance range can be measured in a two-port setup.

I suggest to learn a bit about S-parameters of simple RLC circuits to get an idea how a VNA can be utilized for your measurements.

i want to measure R/L/C components directly. like impedance analyzer.
i am unable to understand how it relate RLC circuit with passive components.

what i am thinking is S21 is a factor for transfer characteristics of DUT, and S11 is reflection factor.

please clarify me on this.

thank you

Yes you can. Either you consider your DUT as a 1-Port network or you can also doing it by connecting your device between the two VNA ports. You will have anyway to convert first the measured S-Parameters to Y-Parameters, the expressions can be found easily on the internet or any graduate level book.

Due to the component reciprocity, you can use either Y11 or Y22 to calculate your values. Remember that in this case Y11 = Yin = G + j*w*B. For a capacitance you will have then:

C = Im(Y11 or Y22) / w

In case you want to measure a resistance or an inductance you have to convert first Yin to Zin = 1/Y11, = R + j*w*L. The resistance is of course the real part of this expression and the inductance can be calculated as I did previously with the capacitance.

Hope that helps.