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Geometry Sequence
In Global Definitions - Parameters and Variables 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 re-running 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: You need to complete the first two sections Model Wizard and Global Definitions - Parameters and Variables before defining the geometry.
Start by defining one arm of the circulator, then copy and rotate it twice to build all three arms.
Rectangle 1
1
On 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.
Copy 1
1
Right-click Plane Geometry  and from the Transforms menu select Copy .
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. Then click on the rectangle when it is red so that it turns blue. The object r1 is added to the Input objects list on the Settings window for Copy. 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 check box.
Rotate 1
1
Right-click Plane Geometry  and from the Transforms menu select Rotate .
2
To select only the object copy1, which lies underneath the object r1, move the mouse pointer to the Graphics window and hover over the rectangle r1 so that it turns red. While the rectangle r1 is red, use the mouse wheel and then click when the rectangle underneath (copy1) is selected.
3
Go to the Settings window for Rotate. Under Rotation Angle in the Rotation text field, enter 120.
4
Click the Build Selected button and then click the Zoom Extents button  on the Graphics toolbar. The geometry should match the figure so far.
Copy 2
1
Right-click Plane Geometry and choose Transforms>Copy .
2
Select the object r1 only and add it to the Input objects list in the Settings window for Copy.
3
Click the Build Selected button.
Rotate 2
1
Right-click Plane Geometry and choose Transforms>Rotate .
2
Select the object copy2 only.
Note: If you cannot locate copy2 in the Graphics window, click the Home toolbar, then click Windows and choose Selection List. From the Selection List, right-click copy2 and choose Add to Selection to add it to the Input objects list.
3
Go to the Settings window for Rotate. Under Rotation Angle in the Rotation text field, enter -120.
4
Click the Build Selected button and then click the Zoom Extents button on the Graphics toolbar.
The geometry should match this figure.
Next, unite the three arms to one object.
Union 1
1
Under Work Plane 1 right-click Plane Geometry and choose Boolean Operations>Union .
2
Select the objects r1, rot1, and rot2 only and add these to the Input objects list in the Settings window for Union.
3
Click the Build Selected button. There is one object created called uni1.
Now, build the central connecting region and add the ferrite domain. During these stages, the geometric design parameters are used. Start by creating a triangle connecting the arms and then by subtracting a copy of what has already been drawn from a circle of proper radius.
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.
Copy 3
1
Right-click Plane Geometry and choose Transforms>Copy . A Copy 3 node is added to the sequence.
2
Select the object uni1 only.
Difference 1
1
Right-click Plane Geometry and choose Boolean Operations>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
On the Home toolbar click Windows  and choose Selection List.
5
From the Selection List, right-click copy3 and choose Add to Selection to add it to the Objects to subtract list.
6
Click the Build Selected button.
The geometry should match this figure so far.
Now, rotate the newly created triangle 180 degrees and use one scaled copy of it to create linear fillets for impedance matching. Use another scaled copy to define the ferrite.
Rotate 3
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.
Copy 4
1
Right-click Plane Geometry and choose Transforms>Copy .
2
Select the object rot3 only.
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 and Variables).
3
Select the object copy4 only.
4
Click the Build Selected button.
Union 2
1
Right-click Plane Geometry and choose Boolean Operations>Union .
2
Select the objects uni1 and sca1 only. Use the Selection List to select the objects if required.
3
Go to the Settings window for Union. Under Union click to clear the Keep interior boundaries check box.
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 rot3 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 on 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.