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Trl calibration with Matlab program for wr90 x-band waveguid

Question asked by samaneh on Nov 5, 2010
Latest reply on Dec 21, 2010 by Dr_joel
Hi every body,

Currently I am working on TRL calibration of wr90 coaxial-rectangular waveguide. I have to write a matlab code for that. I first use a SOLT calibration to calibrate the cables in frequency range 10 to 13 GHz. Then I connect two coaxial-rectangular waveguide directly (Thru connection) and measured scattering parameters. and also put a line between coaxial-rectangular waveguides (line connection ) and measured scattering parameter and Finlay used a short connection and measured scattering parameter for both coaxial-rectangular waveguide. Afterwards I used this measured scattering parametrise in my matlab code which I wrote based on 8-term mat lab model. I wrote my matlab code according to TRL calibration method of Doug Rytting.

in order to check my calibration I measured scattering parameters of PVC sample with my calibration and calibration of Vector network analyzer. My result are not as well as the result of network analyzer calibration. I have some difference in magnitude in comparison with result of calibration of network analyzer. I do not know what is wrong with my calibration. should I use 12 term error correction instead of 8-term or not.

Actually if I ignore isolation problem I will have 10 -term error correction which 2 of them return to source mismatch. I did not consider source mismatch correction for my calibration because I assume it will be correct while I am measuring scattering parameter of standard connections due to used SOLT calibration first. I thank you in advance and look forward to hearing from you if you have some ideas regarding my process. pleas find the attached figure regarding to comparison of scattring parameters of PVC once with my calibration once calibration of VNA.

Best Regards