Unknown Thru calibration using waveguides
I have to characterize sections of waveguide cascaded together as a part of the characterization procedure for use in my set up. All the measurements that I am doing are in the E band(76 to 81GHz). I am using the VDI calibration kit for my calibration procedures. I am using the E8361A with N5260-60003 extenders. I have a few basic questions on the unknown through calibration.
1. Do I have to modify the calibration kit to do the unknown thru calibration or is it sufficient to modify the calibration method that comes up as a part of the smart guided calibration and then choose the unknown through calibration?
2. Once the calibration is done and the cal coefficients computed, if I leave the thru(the unknown thru that I have used as a part of the calibration routine) will the S21 indicate the loss of the unknown thru?
3. Since I am using waveguide structures sometimes it becomes difficult to connect any other structure as a through to verify the calibration.
One of the pics of unknown thru section is attached.
Best Regards
Sorry for the late reply. Didn't see this question.
1 and 2: yes and yes. You do not need to modify the cal coefficients and it will show the true S21 value (subject to 180 degree ambiguity you have with waveguide).
3. you can verify calibration also by adding an waveguide section with a short. If there is low ripple, the calibration is probably good on that port. You can also use a waveguide to coax adpater to make a flexible thru (for example using 1 mm coax cable) and use that as the unknown thru. It may make it more convenient for your situation.