Thanks for information , i will help me a lot , i want to ask one more thing about this . we can measure from PNA a1,a2,b1,b1, r1,r2 from 2port VNA. how can i find Exx , if i dont have these values , how to use VNA (a1,a2,b1,b1, r1,r2 ) to calibrate? is there any way to get Exx or can we just ignore and move for forward just like consider Exy = 0 and Exx = infinity

The PNA does not use the 8 term error model itnernally. But you can convert the 12 term (well, actually 10 term as the crosstalk terms are almost always set to zero, and in fact not used in the 8 term model) through a simple math equation given on page 130 of my book: