Solution type in HFSS

- December 2, 2018 at 7:54 pm
  
  bamdadslr
  Subscriber
  
  Hi all
  I want to simulate a structure in frequency range of 10 Hz to 5MHz. My prediction is that it will have a few resonances in this frequency range. What kind of adaptive solution should I choose? Broadband or multi frequencies? And what type of sweep suits this simulation? Fast or interpolating?
  
  Thank you so much for youe help in advance.
- December 6, 2018 at 9:45 pm
  
  Sorceress Gia
  Ansys Employee
  
  Use the broadband solution setup and the interpolating sweep. Also keep in mind that if this is a radiating structure that it needs to be placed within a finite volume of air/vacuum that should pad the outer boundary of the radiating structure by lambda/2, which at 10Hz is impractical. You may want to consider using ANSYS Maxwell for this simulation.
  
  Best,
- December 7, 2018 at 12:46 am
  
  bamdadslr
  Subscriber
  
  Hi peter,
  
  Thank you so much for your answer. The structure I am simulating is a cylindrical rod surrounded by resistive soil modeled as a hemisphere. I am trying to find the input impedance of the grounding rod in the frequency range of interest. You think that Ansys Maxwell eddy current module is more suitable for this case?
  
  Regards,
  
  Bamdad Salarieh
- December 7, 2018 at 9:53 pm
  
  3Asif
  Subscriber
  
  Hi Bamdadslr,
  
  At lower frequency, (like 10Hz, 20 Hz), the EM equations are not 'tight' with each other.
  In such cases, you may utilize Q3D solver from Ansys. That is good from DC to some moderate frequency.
  
  The frequency range that you described is actually in the sweet spot for Q3D.
  
  Regards.
  3A
- December 8, 2018 at 4:58 am
  
  bamdadslr
  Subscriber
  
  Hi 3Asif
  Thank you so much for your answer. The most important part of my simulations is at higher frequnecies actually, because it will have resonances there, and almost contant behavior upto say 1 kHz. So the lower frequency is not a big challenge but definitely need accurate results as well. So you think for simulating from say 100 Hz to 5 MHz, Q3D works better?
- December 11, 2018 at 1:11 am
  
  3Asif
  Subscriber
  
  You can use the "Enable Q3D for DC" inside HFSS to have better transition from low frequency (DC) world to the high frequency world.
  
  Also, the electrical size matters. If your structure is not very large, 5MHz is okay for Q3D.
  
  However, the 100Hz is really a lower fidelity end for HFSS.
  
  HFSS does not solve DC, it interpolates. If you use Q3D for DC point (from inside HFSS), it is expected to improve things.
- December 11, 2018 at 11:25 pm
  
  bamdadslr
  Subscriber
  
  Dear 3Asif,
  
  Thank you so much for your information, it is definitely of great help for me. The one last question is how to use Q3D from inside HFSS?