HFSS - exciting higher order modes in waveguide

Hi all,

This one has me stumped!

I would simply like to excite the TE20 mode within an X-band waveguide using waveports. I have been playing about with the integration lines but cannot get any field pattern other than the fundemental TE10 mode to propagate. It goes without saying but I am exciting the waveguide well above the cutoff of the TE20 mode.

Also, how would one go about exciting a higher order TM mode rather than the TE mode. Again, I have been playing about with the ports but I am lost

Many thanks for taking the time to reply.

Regards

Keith

Hi !
You need to define more number of modes in the waveguide port
or to use proper boundary (symmetry) conditions - combination of perfect H and perfect E

Thanks for the reply.

I have already tried this but with no success. I am obviously doing something wrong somewhere!

Could you provide more detail?

regards

Keith

when u set up waveport, u must choose Number of Modes, where default value is 1. After simulation finished, you can check excited mode field distribution from Port Field Display. Then go to Field Overlays--> Edit Source, you can choose which mode you want excite, and you can assign both amplitude and phase for excited mode.

Regards,

Many thanks!

i have the same problem if u solved it plz tell me

You need to go to high enough frequency to reach the cut-off freq according to the size of the waveport:
fc (TE20)= c/(a√εr)
where a is the width of the waveport. So you must go beyond the fc (f>fc).
Also, you must increase the number of mode in the settings.

Let me know if it works.

thanks a lot!solved my problem too