When performing 1-port waveguide calibration (X11644A, Short, 1/4 Offset-Short, Load), what is usefull method to verify that calibration is properly done?
I thought there was something described in the manual about using the precision airline, terminated in a short. The maximum magnitude of the ripples tell you how good the calibration is.
For what it is worth, I was at a Keysight mm/THz meeting a couple of years back. There was a presentation by someone at the National Physical Laboratory (NPL) on verification of calibration at mm/THz frequencies. They were developing a standard based on two different waveguides of different sizes butted together. Luckily its easier at mm/THz frequencies, as there's a standard flange design, so its easy to **** different sizes together. The guy at NPL was using one of the EM simulation packages (I think CST) to come up with a numerical solution, and compare that to the what was observed. I mentioned I'd be tempted to use two different packages (e.g. HFSS too), as I'm always a bit skeptical of EM simulation software. I know from experience, it is easy to get the wrong results due to user error.
IMHO, using a program like HFSS, you really do need access to a support engineer, whereas I know a lot of people have pirated copies, have no support, and so get frustrated if measurements don't agree with simulations. Of course NPL would not use pirated software, but the basic principle is that I don't trust one bit of software for those sort of things.
I have looked hard to find a closed-form analytical solution to the problem of two different sized waveguides joined together, but have never managed to do so.
1) leave the waveguide port open. Depending on the edge quality, it should have about 12.4 dB return loss (somewhere there is a paper computing the reflection from a truncated waveguide).
2) put on the load with the 1/4 offset. It should be 6 dB worse than the load spec.
But you would be better using short; offset short; load; offset load. then you can measure the load (the 1/4 offset becomes the impedance reference. To do this edit the kit to add 1/4 offset load to you standards as a load standard.
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