Make Object solid, Focus on an area on object, Optimizing mesh and Feko solver settings

Wayne K

I have several questions:

1. How do I make ‘Union1_FINISHED’ object a solid? I know ‘Loft1’ under ‘Union1_FINISHED’ is a solid.  I have surfaces on the bottom, which I know will screw up the results. Not sure how to make it a complete solid.
2. I am only interested in the area inside (Target Under Test) ‘TUT_union1’ area. How would I go about only evaluating that area and comparing it to other measurements when I have made adjustments to the model? Also, it there a way to run OPTFEKO where it is only looking at that ‘TUT_union1’ area and making that return small.
3. What is the optimal setting for mesh size for 2 GHz, like a varying mesh size.
4. What is the optimal setting for running FEKO solver this size (25 ft by ~18ft) that is a plane wave and monostatic? I looking to run 500MHz, 1 GHz, and 2 GHz.

L_W_R__D_d_T_t_input_v8_TUT.cfm

L_W_R__D_d_T_t_input_v8_TUT.cfs

L_W_R__D_d_T_t_input_v8_TUT.cfx

L_W_R__D_d_T_t_input_v8_TUT.pre

Mel

1. How do I make ‘Union1_FINISHED’ object a solid? I know ‘Loft1’ under ‘Union1_FINISHED’ is a solid.  I have surfaces on the bottom, which I know will screw up the results. Not sure how to make it a complete solid.

The problem is there are Wires inside the Union and these wires are coincident with the edges. Wires are free edges not connected to anything. This is why the "solid" is not presenting as fully solid.

I am not sure how the model ended up this way, but you can fix it as follows:
Copy out the 3 parts from Union1_FINISHED

Select Union1_Bez_surface (the one that was just copied out) and copy all the faces.

Delete the Union1_Bez_surface part that is inside of Union1_FINISHED.

Union the copied out faces.

Union this new Union with the parts "Bottom" and "Loft1"

This gives a full solid - note there are now 2 regions where previously there was only 1. You could consider deleting the internal face that causes there to be 2 regions.

Delete all remaining parts except the "Union1" and "TUT_Union1".

2. I am only interested in the area inside (Target Under Test) ‘TUT_union1’ area. How would I go about only evaluating that area and comparing it to other measurements when I have made adjustments to the model?  Also, it there a way to run OPTFEKO where it is only looking at that ‘TUT_union1’ area and making that return small.

If I understand correctly, you want the contribution to the RCS only from this TUT_union1 area. You must first Union this with Union1 since it is in contact with the solid. This creates a Face on the solid. On the far field request, set the Scope tab to use only this face. The RCS will be computed only from this Face. OPTFEKO will evaluate the far field request and take into account this setting automatically.

3. What is the optimal setting for mesh size for 2 GHz, like a varying mesh size.

For plane wave incidence a mesh size of around 1/6 of the wavelength should be a good starting point.

4. What is the optimal setting for running FEKO solver this size (25 ft by ~18ft) that is a plane wave and monostatic? I looking to run 500MHz, 1 GHz, and 2 GHz.

The MLFMM should be used with the Combined Field applied to all the Face properties. All face normals must point towards the outside of the solid.

The bandwidth is very wide. I would suggest splitting the model into two different frequency bands. Model 1 to solve for 500 MHz and 1 GHz (meshed for 1 GHz) and model 2 to solve for 2 GHz only.

The 2GHz version is attached.

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image6.png

image7.png

L_W_R__D_d_T_t_input_v8_TUT_alt.cfx