List of issues:
1) When simulating the waveguide in CST FDTD solver (or CST F solver), the reflection S11 is below -90dB, openEMS gives values below -60dB but depending on the specified frequency range or z boundary PLM settings, it can vary. Is this a numerical noise limitation or something else? It could be an issue when designing waveguide filters or diplexers that require high isolation/rejection in the stop band.
2) When the openEMS waveguide model is changed from a normal waveguide structure using PEC with a finite wall thickness to just a waveguide defined only by the x and y boundaries being PEC, the S11 reflection now gets worse and is between -50 and -60 dB. The result should be identical to when the waveguide is defined by a rectangular channel of PEC. I don't know why there is a difference.
3) When taking the "realistic" rectangular waveguide model and replacing the PEC metal definition with a material definition with a given conductivity (kappa), the S11 is terrible regardless what conductivity I use that is close to any metal from brass, copper to silver. Also there is what seems like an oscillation on the S21 when you zoom into the plot. Is this a case of using the material definition function incorrectly?
I will post the two script files followed by some pictures, in this and the following thread.
Rect_Rect_WaveguideadapterWG20.m- Waveguide model with finite wall thickness.
- (6.26 KiB) Downloaded 49 times
- Rect_Rect_WaveguideadapterWG20_PEC.m
- Waveguide model with PEC boundaries.
- (6.19 KiB) Downloaded 49 times
- CST model
- CST WG20 Model.png (28.5 KiB) Viewed 673 times