How to measure digital phase shifter

Hi,
I've been designing 2-bit phase shifter based on microstrip,
all i want to ask is how to measure the phase shifter to gain the S-parameter?

Thanks

Use a calibrated VNA, it outputs all you need.

hi, jiripolivka thanks for the reply,

But also how to know the responses of each state?, i mean if i want to know the response of state 0 1 how do i test it in VNA?