Two optional waveport sizes in HFSS. Which one is better?

[jianke]

Hi everyone,

TO get a correct waveport size, I run "PortOnly" simulation in HFSS. But there are two optional port sizes which seem both correct. Can you please tell me which one is more correct/better?
(1) Port-Height=2.6mm => Port-Width=3.79mm;
(2) Port-Height=3.5mm => Port-Width=3.76mm.

The employed substrate is Rogers6002, with 0.508-mm thickness. The designed bandwidth is from 29.26 to 35.56GHz. The center freq is 32.4GHz. So the microstrip line width is 1.362mm (from ADS). I need a port size which allow fundamental mode up to 36GHz.

The other information are: 5*PortH=2.54mm; 10*PortH=5.080mm;
5*PortW=6.810mm; 10*PortW=13.62mm

Thank you very much.
View attachment HFSS_Files.zip

 

[jianke]

Updated simulated results

 

[PlanarMetamaterials]

Hi Jianke,

A few questions:

- Can you get the fields of the second mode?
- Can you plot the mesh?

 

[jianke]

Hi, Thank you very much for your reply. The plots of your request are attached for your review. Looking forward to receiving your answers. Thank you.

View attachment Dis_Mesh.doc

View attachment Dis_Modes.doc

 

[PlanarMetamaterials]

Hi Jianke,

The "second mode" generated by HFSS looks like a TM0 surface-wave mode. This shouldn't have a cutoff frequency, so I'm not sure what's going on there -- however, this mode's properties will be strongly dependant on the size of the waveport due to its uniform properties.

The "third mode" is the mode which I assume you want to be cut off above 36 GHz. This has a TM01 - type field distribution, and should be fairly leaky -- I'm guessing this is why you don't want it.

It looks like you may be confusing the second mode with the third in your above plots. Can you identify the three modes in those images? Also, I was wanting the mesh on the port face, it looks like you've plotted it from the top looking down on the MS.

Thanks