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Combining Calibration Terms

Question asked by tony on Jun 1, 2012
Latest reply on Jun 1, 2012 by Dr_joel
Hello, I'm working on automating testing DUT with 6 inputs and 6 outputs. We have a switch box capable of routing the PNA-X port 1 to any input on the DUT, and PNA-X port 2 to any output on the DUT. This gives us a total of 36 possible paths to calibrate. The end user does not wish to calibrate this many paths. 

So the idea is to calibrate the six input paths, then the six output paths, and then combine the calibrations to form the full calibration for any given path.

I do a full 2-port calibration on the six input paths (holding the output path constant), and six output paths (holding the input path constant) and save the 12 error terms for each calibration.

I would like to combine these error terms to create the error terms for the other missing paths. However I'm having trouble accomplishing this.

for example:
I want to create the Calibration for path Input 3 to Output 5 (3-5),
I have the 12 error terms from the 2-port calibration for paths Input 3 to Output 1 (3-1) and Input 1 to Output 5 (1-5)
I also have the 12 error terms from the 2-port calibration for a reference path Input 1 to Output 1 (1-1)

how do I combine the twelve terms from 3-1 and 1-5 (and 1-1 if necessary) to generate the cal terms for 3-5?

I seem to have figure out 10 out of the 12 error terms. Its the Forward and Reverse Transmission Tracking error terms that are my main concern.

(hopefully these are correct)
Forward Directivity, Source, and Reflection from 3-1
Reverse Directivity, Source, and Reflection from 1-5
Forward and Reverse Isolation are always zero
Forward Load Matching from 1-5
Reverse Load Matching from 3-1
Forward and Reverse Transmission Tracking????