Single cell Simulation and full-wave simulation

[Henry797]

Hi All CAD geniuses,
Can you perhaps let me know the difference between single cell simulation and full-wave simulation in any CAD software (ADS Momentum, HFSS, or CST)?
Many Thanks
Henry797

 

[Jameslu]

Hi

You can reference as below to understand what the full wave simulation.

https://www.edaboard.com/threads/28846/

thanks

 

[Henry797]

If known, can you also let me know if I'm designing a device operating at mm-wave say 87GHz(3.4mm), Do you think a full-wave simulation is possible to perform? [Ofcourse it depends on the design as well, as in my case I'm designing an antenna array, where I wanted to start with single cell simulation (quasi-static approach)]
And also wanted to know, if I'm performing full-wave simulation, does it mean that there cannot be any boundary conditions? Because from the thread that you've given, it said, full-wave simulation takes into account all the Maxwell's equation, with no restrictions in form of boundary conditions. Hence if I'm using CST, a full-wave simulation is one that will have no boundary conditions. Please correct me if I've understood wrongly.

 

[Jameslu]

Hi

sorry,i didn't have CST simulation experience.
In the HFSS, it is need to set the boundary condition of free space (air box) for simulation and according to the HFSS full book suggest as below
The Radiation Boundary needs to be placed at least lumpda/4 from radiating devices.
the bigger is better for air box, because it will relation to simulation accuracy (decrease reflection wave and wave absorption ability).
the HFSS can use the auto setting for building the boundary condition.
Maybe the CST have auto setting the boundary condition in the simulation.

sorry my English. if i am wrong, Please share your experiences with me.

thanks

 

[Henry797]

HI Jameslu,
Thank you for your reply. You mean to say that I will perform a full wave simulation if and only if I lay no restrictions to the simulation, in other words I will choose the background as air, and the electromagnetic waves will propagate throughout an infinite plane in 3D. It might be in CST, HFSS, or any other CAD file, i'm sure they are all capable of performing these simulations. Is that what you are trying to say?

 

[Jameslu]

Hi

if you lay no restrictions to simulation (an infinite plane in 3D).
i think, the numerical analysis of HFSS or CST cannot to convergence and cause to simulation results damage.
In other words, we need to limited the waves propagate space for simulation in the HFSS or CST and get close to theory results.

sorry my English. if i am wrong, Please share your experiences with me.

thanks

 

[Henry797]

Hi Jameslu,
Thanks for your reply. I've simulated so many microwave devices using CST without using any boundary conditions, I mean all open boundary, just considering the background as normal(air). There was no restrictions using Et=0 or Ht=0. Now my question is without even knowing did I actually compute a full wave simulation? Do you have suggestion to add?

 

[Jameslu]

Hi

my pleasure, i have learned a lot of concept, too
Did you saw what is difference between them of simulation results?

In addition, Could you please help explanation Et=0 or Ht=0 of CST setting?

thanks

 

[Henry797]

Yes to tell you truly, I wanted to know the real definition of full-wave simulation and also when I'm using computational analysis, I want to know where and how I'm applying full-wave simulation.
Coming to your question, in CST there are several boundary conditions you can use. Of them pretty useful conditions are Et=0 [representing tangential component of the E-field must be zero on that very plane] and Ht=0[representing tangential component of H-field must be zero on the very plane as well. Now you can use these boundary conditions along with the background environment to confine the simulation into a less complex and less time consuming process. But what I know from theory is a full-wave simulation is not restricted to any confined boundary condition.
I hope this helped you. Let me know if you wanna know more about different modes of E & H field in CST.