Learning Forum

[bharathgkashyap]

Hello,

I am trying to create a curved antenna confromal to an elliptical surface. I am using 'wrap' command to make the planar antenna conformal to the surface. However, I notice some issues while doing this. 

1. After wrapping, a gap appears between the 3D object and the wrapped sheet (which I believe should not happen). This gap is also not uniform and reduces to 0 at some locations and increases again. (Please see the pics attached below).

 

2. This issue further extends upon adding thickness to the sheet. The sheet with thickness intersects with the 3D object (ellipse) that it was wrapped to at some locations. This gives 'intersection error' during design validation. Even subtracting the thickened sheet from the ellipse doe not resolve the issue (looks like subtraction does not account for these local variations). Only way to resolve this and simulate is to choose the 'Enable Material Override' option in HFSS --> Design Options. But noy sure how it can affect the meshing or if it can cause any numerical errors.  

This seems to be specific to such curved geometries and does not impact the planar designs. 

 

3. Further, with the curved geometries, uniting the top metal layer, the bottom ground plane and the vias in a 2 layer design vs. not uniting them changes the results significantly. Again this does not happen with planar geometries. 

Has someone else come across these problems. Is there a way to fix these issues?

In general is there a better way in HFSS to design such conformal structures with thickness? 

Thank you in advance!

 

[Praneeth]

Hi Bharath,

Thank you for reaching out to the Ansys learning forum. 

Please go through my suggestions in line with your questions:

1. This gap might be because of the optimistic rendering of curved objects. Please change the settings in the curved object visualization (View menu > Render >) and check the same.
2. Point 2 will not be valid if the issue is because of the rendering. Did the error message mention the two objects (wrapped sheet and elliptic body) are intersecting? Please check once. Also, you can delete the elliptical object if it is created only for wrapping purposes. 
3. Designing vias in the wrapped bodies might be tricky, but the results should not change whether they were united or not. If you are using terminal option in the solution type, you can check the nets associated with these objects for confirmation (Right click on excitations > show nets) in both cases.

Best regards,
Praneeth.

[bharathgkashyap]

Hi Praneeth, 

Thank you for your suggestions.

1. I don't think it is related to the rendering of curved objects. I have tried by changing the settings on 'curved object visualization' option to both lower and highest resolutions. In my experience, I have only seen it affecting how the curved edges look, but has no impact on the design validation.
2. Yes, the error specifically mentions that the two bodies intersect. Interestingly this error only appears when we add thickness to the wrapped sheet and does not appear when the wrapped sheet has no thickness (although the wrapped sheet without thickness still intersects the 3D body as seen from the above images). The elliptical body is a part of the simulation, as such, it can't be deleted.
3. Yes, I agree that the results should not change with uniting or not uniting. ( And I have seen it not change with the planar designs). However, it seems to change with the curved designs, and I am not sure why. Also, I have been using 'modal' solution type, but try with 'terminal' and check as well.

 

[Praneeth]

Hi Bharath,

Generally, with optimal rendering curved objects are seen as segmented objects. So, the curved object visualization setting was suggested to view the curved objects more clearly. 

Based on your response, it looks like there might be some corrections required for wrapping your model. If you are still facing the same issue, then please go through this free AIC lesson - Simulation of Microstrip Filter in Ansys Nuhertz filter | Ansys Courses (9.17 time stamp onwards) for the steps of wrapping.

Best regards,
Praneeth.