Hello.
When I run a simulation for a simple rectangular waveguide in a frequency range that includes the cutoff frequency, I should see a change in the S-parameters that show the cutoff behavior of the wave stream. But S11 does not show what should come out according to calculations.The cutoff frequency should be at 6.5-13 GHz. The waveguide itself is 23x10 mm length 1000, wall width 1 mm.According to calculations here only TE10. I use Time Domain Solver. Boundary Add Space.
I would like to clarify the length of the waveguide is just 1000 mm, there is still a gap in the waveguide in the form of a dumbbell, where the width is 0.5 mm, the radius is 2.5 mm, it is located in the middle of the narrow wall of the waveguide