Changes
In this tutorial you will learn how to import several external CAD models, transfer them to [[EM.Tempo]] and combine them with your own object drawings. You will construct a physical structure with different types of materials, especially a lossy dielectric. You will use a new type of mesh generator for discretization of this structure.
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==Getting Started==
|-
! scope="row"| Dielectric_1
| Dielectric
| Orange
| Flesh
| ε<sub>r</sub> = 65, μ<sub>r</sub> = 1, σ = 0.6S/m, σ<sub>m</sub> = 0
|-
! scope="row"| Dielectric_2
| Dielectric
| Light green
| Plastic
| ε<sub>r</sub> = 2.2, μ<sub>r</sub> = 1, σ = 0, σ<sub>m</sub> = 0
|}
Note that Dielectric_2 Dielectric_1 has a very high relative permittivity and a large electric conductivity. At the center frequency of 900MHz, this is equivalent to a tangent loss of:
<math> \tan\delta = \frac{\epsilon^{\prime}}{\epsilon^{\prime\prime}} = \frac{1}{\epsilon^{\prime}}\frac{\sigma}{\omega\epsilon_0} = \frac{0.6}{(60)(2\pi \times 9\times 10^8)(8.854\times 10^{-12})} = 0.186S/m </math>
== Importing the External Model Files ==
In [[EM.Cube]], external objects are always imported to [[Building_Geometrical_Constructions_in_CubeCAD | CubeCAD]] [[Image:cubecadlogo.png]] first. From [[Building_Geometrical_Constructions_in_CubeCAD | CubeCAD]] you can transfer an imported object to any of the other computational modules. To import the human head model, go to '''File Menu''' and select <b>Import...</b>. The standard Windows Open dialog opens up with the file type set to ".STP". Browse your folders to find the downloaded CAD model file named "Human_Head.STP". Select it and click the {{key|Open}} button. The head model appears in the project workspace of the [[Building_Geometrical_Constructions_in_CubeCAD | CubeCAD]] Module. Repeat the same procedure for the other CAD file named "Radio.STP" and import it to [[Building_Geometrical_Constructions_in_CubeCAD | CubeCAD]]. A total of four solid objects are imported to [[Building_Geometrical_Constructions_in_CubeCAD | CubeCAD]] as follows:
*Solid_1: Human Head
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[[Image:Tempo_L11_Fig1.png|thumb|left|720px|The imported human head and radio models in [[Building_Geometrical_Constructions_in_CubeCAD | CubeCAD]]. One of the four objects has been selected.]]
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Next, you have to move all the imported solids to the various material groups in [[EM.Tempo]]. To do so, first select "Solid_1" in the navigation tree of the [[Building_Geometrical_Constructions_in_CubeCAD | CubeCAD]] module, then right-click on it and select <b>Move To → [[EM.Tempo]] → Dielectric_1</b> from the contextual menu. The human head solid will disappear from [[Building_Geometrical_Constructions_in_CubeCAD | CubeCAD]] and will reappear in [[EM.Tempo]]'s workspace under the Dielectric_1 group with an orange color.
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In a similar manner, move objects Solid_2 and Solid_3 from [[Building_Geometrical_Constructions_in_CubeCAD | CubeCAD]] to the PEC_1 group in [[EM.Tempo]] and move object Solid_4 from [[Building_Geometrical_Constructions_in_CubeCAD | CubeCAD]] to the Dielectric_2 group in [[EM.Tempo]]. At this time, the physical structure in [[EM.Tempo]]'s project workspace should look like this:
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Once the top face is highlighted, click the left mouse button to complete the primitive extraction process. A new surface object called "Surface_1" is added under the Dielectric_2" group. Move this object to the PEC_1 group in the same way you moved objects earlier from [[Building_Geometrical_Constructions_in_CubeCAD | CubeCAD]] to [[EM.Tempo]]. This completes the geometrical construction of your physical structure for this project.
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Generate and view the mesh of the human head and the radio unit. A 206 208 × 169 171 × 239 240 grid space is generated, which amounts to a total of more than 8.3 5 million cells. You have a very large computational problem at hand. Keep in mind that [[EM.Tempo]] generates the Yee mesh at the highest frequency of the bandwidth, which is 1.2GHz in this project.
{{Note|If your computer's RAM memory cannot handle the specified mesh settings, reduce the mesh density.}}
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Also plot the 2D polar pattern graphs in EM.Grid. From the YZ-plane graph, you can clearly see that the radiation pattern of the monopole antenna is no longer omni-directional.
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Finally, plot the S<sub>11</sub> parameter of the antenna in EM.Grid. You can see from the figure below the return loss is minimized around 835MHz.
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<p> </p>
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