When we study about calibration, usually 12 error terms 8 error term are found along with various method like TRL , LRL , SOLT etc.

When we see any two port VNA we have a1,a2,b1,b2, r1, r2 . we need to calibrate using these terms only.

1. How can we find calibration parameters from the above 4 parameters (a1,b1, etc) like ESR，ESF ,ELF etc?

2. What minimum parameters I need to use from 12 error terms for manual calibration?#

Chapter 3 of the book "Handbook of Microwave Component Measurements" by Dr. Joel Dunsmore has an extensive coverage of various VNA calibration techniques that the formulas for calculating the error terms from the standard measurements.