HFSS Simulations with Microstrip Lines

[hertz]

microstrip shielded microstrip hfss

Hi all,

I need help on microstrip simulations. I am trying to simulate a simple microstrip structure with waveports. I specify 3 modes at each port. I am not sure if I need to draw calibration lines for mode 2 and 3? When I look at the port excitation of mode 2 and 3, they look like waveguide mode excitation. I am not sure how to interpret this? Is this the correct way to simulate higher order modes on microstrip line in HFSS?

Thanks,
Hertz

 

[atorrezan]

I also had this problem. What would be the correct way to use the HFSS in order to obtain a modal analysis?

 

[haydar]

In my microstrip coupler design, I used driven mode analysis and waveports. I have not used calibration lines, modes, or anything else.

 

[fekete]

Almost certainly you only want the S parameters for the fundamental mode. Then you don’t have to define impedance lines for the others (which would be difficult). The simulation will include the loss/conversion to those modes anyway. In fact there is an example in the HFSS manual, chapter 6.5
Note that some of those higher order modes that look like waveguide modes might be artifacts of the port boundaries – which are PEC by default. So instead of simulating a laterally and top open microstrip incoming from the outside to the port you are simulating a shielded ms connected there and what you see are those modes. Nevertheless sometimes you have to include them for more accurate high frequency simulations.

 

[hertz]

Thanks fekete...which manual are you refering to? Is it possible to download from HFSS website?

 

[fekete]

You can download the manual for version 9.2 from this board:
**broken link removed**