Do anyone know why the group velocity of microwaves inside a rectangular waveguide goes up when frequency goes up? To me it seems like a higher frequency means a smaller wavelength, and thus a more ZIG ZAG patterns off the walls (to meet the boundary conditions). If the wave is zig zagging more, then it must be propagating down the waveguide at a slower rate? Yet group velocity goes up (every resource says this). Can anyone help me on this?