Guilin Sun
Ansys Employee

Might not be right, as you can check that such waveguide will support other mdoes if you have a TE mode with larger modal area. Please check the number of modes with more number of trial modes. Before the cut off condition such waveguide may support more modes. I believe that you can find an analytical expression for the single mode condition. Please serach "ridge waveguide, single mode", or refer this article