Geometry Sequence
In Global Definitions - Parameters parameters were entered to prepare for drawing the circulator geometry. Once the geometry is created, you can then experiment with different dimensions by changing the values of sc_chamfer and sc_ferrite and rerunning the geometry sequence. These step-by-step instructions build the same geometry that is contained in the application library file lossy_circulator_3d_geom (imported in the section Geometry).
The geometry is built by first defining a 2D cross section of the 3D geometry in a work plane. The 2D geometry is then extruded into 3D.
Note: Repeat the modeling steps in page 20-21. You need to complete the first two sections Model Wizard and Global Definitions - Parameters before defining the geometry.
Start by defining one arm of the circulator, then rotate it twice to build all three arms.
Rectangle 1
1
In the Geometry toolbar click Work Plane .
2
Under Work Plane 1 right-click Plane Geometry and choose Rectangle .
3
Go to the Settings window for Rectangle. Under Size:
-
In the Width text field, enter 0.2-0.1/(3*sqrt(3)).
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In the Height text field, enter 0.2/3.
4
Under Position:
-
In the xw text field, enter -0.2.
-
In the yw text field, enter -0.1/3.
5
Click the Build Selected button.
Note: To turn on the geometry labels in the Graphics window, in the Model Builder under Geometry 1 > WorkPlane 1 > Plane Geometry, click the View 2 node. Go to the Settings window for View and select the Show geometry labels checkbox.
Rotate 1
1
Right-click Plane Geometry  and from the Transforms menu select Rotate .
2
To select the object r1, move the mouse pointer to the Graphics window and hover over the rectangle r1 so that it turns red, and click.
3
Go to the Settings window for Rotate. Select the Keep input objects checkbox in the Input section.
4
Under Rotation in the Angle text field, enter 120 240. When more than one angle is defined, the operation will create the rotated copy for each angle specified.
5
Click the Build Selected button and then click the Zoom Extents button  in the Graphics toolbar. The geometry should match the figure so far.
Next, build the central connecting region.
Circle 1
1
Right-click Plane Geometry and choose Circle .
2
In the Settings window for Circle under Size and Shape, enter 0.2/(3*sqrt(3)) in the Radius text field.
3
Click the Build Selected button.
Difference 1
1
Right-click Plane Geometry and choose Booleans and Partitions > Difference .
2
Select the object c1 only to add it to the Objects to add list in the Settings window for Difference.
3
Go to the Settings window. To the left of the Objects to subtract section, click the Activate Selection button.
4
Select all three rectangles by clicking each rectangle in the Graphics window.
5
Select the Keep objects to subtract checkbox at the bottom of the Difference section.
6
Click the Build Selected button.
The geometry should match this figure so far.
The remaining of the cross-section is generated using geometric parameters, along with rotation, scaling, and union operations.
Rotate 2
1
In the Model Builder under Work Plane 1, right-click Plane Geometry  and choose Transforms > Rotate .
2
Select the object dif1 only.
3
Go to the Settings window for Rotate. Under Rotation Angle in the Rotation text field, enter 180.
4
Click the Build Selected button.
It is now time to apply the first scaling for the impedance matching.
Scale 1
1
Right-click Plane Geometry and choose Transforms > Scale .
2
Go to the Settings window for Scale. Under Scale Factor in the Factor text field, enter sc_chamfer (one of the parameters entered in the step Global Definitions - Parameters).
3
Select the object rot2 only.
4
Select the Keep input objects checkbox in the Input section.
5
Click the Build Selected button.
Union 1
1
Right-click Plane Geometry and choose Boolean Operations > Union .
2
Select the objects r1, rot1(1), rot1(2), and sca1 only. Use the Selection List to select the objects if required.
3
Go to the Settings window for Union. In the Union section, click to clear the Keep interior boundaries checkbox.
4
Click the Build Selected button.
The geometry should match this figure.
Next, apply the scaling for the ferrite region.
Scale 2
1
In the Model Builder right-click Plane Geometry and choose Transforms > Scale .
2
Select the object rot2 only.
3
Go to the Settings window for Scale. Under Scale Factor in the Factor text field, enter sc_ferrite.
4
Click the Build Selected button.
Extruding the 2D cross-section into a 3D solid geometry finalizes the geometry.
Extrude 1
1
Right-click Work Plane 1 and choose Extrude .
2
Go to the Settings window for Extrude. Under Distances from Plane in the associated table, enter 0.1/3 in the Distances (m) column.
3
Click the Build Selected button and then click the Zoom Extents button in the Graphics toolbar.
Form Union
1
In the Model Builder click Form Union (fin) .
2
In the Settings window for Form Union click Build All .
The final sequence of Geometry nodes in the Model Builder should match the figure.
The last step finalizes the geometry and turns it into a form suitable for the simulation by removing duplicate faces, for example. It is performed automatically when material is added or when physics features are defined, but it is good practice to perform it manually as any error messages from this step may be confusing when appearing at a later stage. The geometry should match this figure.
Note: If you skipped to this section to learn how to create the geometry, you can now return to the next tutorial step: Materials.