HFSS mesh problem: simulating a big structure (4m) with a tiny component (1mm).

Hi all,

I am simulating a monopole antenna on the UAV. The UAV is about 4 [m] by 3 [m]. The monopole is put on the wing of the UAV, monopole is 70 [mm] long with a 1.5 [mm] diameter. Frequency is 1 GHz. When I try to mesh the structure, using the default mesh setting, an error occurred: "critical features could not be preserved correctly".

I googled this one, and people say it is because I am simulating a big structure with a tiny component. I am wondering how can I change the mesh setting?

Plus, the simulated UAV is a simplified version, only with a rectangular wing and a rectangular body, no curved or complex structure.

I tried to change the initial mesh setting, set the maximum surface deviation as 1/10 of the smallest dimension, maximum normal deviation 5 deg, and the aspect ratio 10, as shown in the attached pic. But seems that the meshing took a pretty long time... I just want to see the impact of the UAV body to the EM performance of the monopole, so I think I dont have to mesh the whole UAV body using the smallest dimension? Maybe just mesh the particular monopole carefully?



I am really not familiar with this mesh operation in HFSS. Usually I just keep the default mesh setting. Friends, any suggestions on the meshing operation will be appreciated!

Thanks.
Panou

I guess only option is to switch over to simulators such as ADF (Antenna Design Framework) wherein the complete platform + your antennas could be analyzed accurately and quickly.

FEKO could also be of help .. try it out !

Thanks! But it is not easy to purchase another EM solver...

vedagarbhamsandeep said:

I guess only option is to switch over to simulators such as ADF (Antenna Design Framework) wherein the complete platform + your antennas could be analyzed accurately and quickly.

FEKO could also be of help .. try it out !

Click to expand...

What's the version of hfss do you use? if you used newer than v13, you can try the hybrid method in HFSS, such as HFSS-IE (Integral Equation), HFSS-PO (Physical Optics), Hybrid FEM-IE or Enhanced Hybrid IE-Regions.

You have to understand the problem nature, it is a very typical multi-scale problem, which means objects in the problem domain vary from meters to mm or even smaller. Such type of problem is a great challenge nowadays and ongoing research is still being performed. Hybrid method is the solution! However, implementing hybrid is not trivial, if you use HFSS-IE + HFSS-FEM, the boundary integral method for solver communication can be problematic and I am curious to know if ANSYS-Ansoft has resolved this issue perfectly. FEKO + Antenna Magus can be another solution, but to my best knowledge, I've never seen a true multi-scale example released to the public domain. None of them CST, FEKO, ANSYS, XFDTD, ADS .....

panou said:

Hi all,

I am simulating a monopole antenna on the UAV. The UAV is about 4 [m] by 3 [m]. The monopole is put on the wing of the UAV, monopole is 70 [mm] long with a 1.5 [mm] diameter. Frequency is 1 GHz. When I try to mesh the structure, using the default mesh setting, an error occurred: "critical features could not be preserved correctly".
Thanks.
Panou

Click to expand...

I suspect with manual intervention, you can make the mesh finer in the region of interest, and course elsewhere. I don't know how to do it, but I believe it can be done.

rodgerwxh said:

You have to understand the problem nature, it is a very typical multi-scale problem, which means objects in the problem domain vary from meters to mm or even smaller. Such type of problem is a great challenge nowadays and ongoing research is still being performed. Hybrid method is the solution!

Click to expand...

Also, there is software based on raytracing to simulate such applications
**broken link removed**

Delcross has a Shooting and Bouncing Rays (SBR) code called Savant that can do this for high frequencies where the problem size is very large. They can import 3D full-wave EM models for isolated antennas, and then use that to stimulate a hybrid simulation of using SBR to analyze the installed performance of the antenna.

They can import antenna models simulated from CST Microwave Studio, HFSS, the FEKO FEM solver, and WIPL-D. They offer integration with CST to do this automatically, as well as for WIPL-D. You have to contact them to get MATLAB routines to convert HFSS or FEKO FEM models for import into their Savant solver. Here is the product page for Savant: **broken link removed**