how to excite this groove guide resonator?

hi guys, I'm doin this project based on the article A.Sevinc and Levent Sevgi " Millimetre Waveband Semisymmetrical Groove Guide Resonator" IEEE microwave magazine 2004.
At the moment i'm tryin to simulate it using Ansoft HFSS but i couldn't seem to find a way to excite the dominant TE10 mode in the groove region. The resonator should be coupled through the rotatable coupling slot.
Can anyone please tell me which direction should the E-field is on the wave port so that i could get the TE10 in the resonator?
or better yet please tell me if wave port is not the way to go.

any comments, advice are greatly appreciated
Thanks in advance.

regards
enyxep