how can i change the angle (theta and phi) of incident wave in waveguide in HFSS?

Hi, everyone
I am now using HFSS version 13 to calculate S11 and S21 of a metamaterial absorber.
wave ports and PEC/PMC B.C. are set up in the simulation.
For the wave port, the plane wave incident angle is zero in default, but I want to use an oblique incidence(for example theta or phi=10 deg). What should I do to realize oblique incidence?
Thanks

Hi mamase,

Oblique incidence means that the waveguide is not being fed by another similar waveguide, which means it must be fed by a different waveguide supporting different modes, such as free space. You can set up a free space oblique excitation by Assign Excitation -> Incident Wave -> Plane Wave.