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HFSS - exciting higher order modes in waveguide

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Bouk Teef

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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
 

navuho

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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
 

Bouk Teef

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navuho said:
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
 

asdfaaa

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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,
 

Bouk Teef

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asdfaaa said:
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!!
 

wlcsp

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Bouk Teef said:
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

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.
 

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