{{projectinfo|Tutorial|Simulating A Monopole Antenna Interacting With A Human Head Model|Tempo L11 Fig title.png|In this project, a human head model is imported, and its interaction with a monopole antenna is analyzed in EM.Tempo.|
*[[Building_Geometrical_Constructions_in_CubeCAD | CubeCAD]]
*STEP Model File
*CAD Import
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
| Light green
| Plastic
| ε<sub>r</sub> = 2.2, μ<sub>r</sub> = 1, σ = 0, σ<sub>m</sub> = 0
|-
! scope="row"| Dielectric_2
| 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 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 CubeCAD Module. Repeat the same procedure for the other CAD file named "Radio.STP" and import it to CubeCAD. A total of four solid objects are imported to CubeCAD as follows:
*Solid_1: Human Head
== Adding New Parts to Your Structure ==
Activate the "THIN_WIRE_1 " group and draw a vertical line named "Line_1" of length 8.5cm with its LCS coordinates at (0, 0, 0) and rotation angles of (0°, -90°, -180°). With the line tool selected, click on a block space and drag the mouse to start drawing a line. While still in “Draw Mode”, press and hold down the {{key|Alt}} button of the keyboard. This forces the drawn line to be constrained along the alternate Z-axis (normal to the default XY plane on which the mouse pointer moves). This places your monopole antenna at the top of the imported metal base object.
Next, you will build a PEC ground plate for your monopole antenna at the top of the plastic case. You will use the "Extract Tool" for this purpose. Click on the '''Extract Tool''' [[file:ExtractIconLogo.png]] button of the CAD toolbar or select the menu item '''Tools → Basic → Extract'''. Move your mouse close to the monopole and hover over the plastic casing to highlight its top face. As you can see from the figure below, you must be able to highlight the snap point at the center of the top face with rounded corners. If the mouse-over is not easy and it grabs the head model instead, you may have to freeze the object "Solid_1" first just like in the figure.
</table>
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 [[CubeCAD]] to [[EM.Tempo]]. This completes the geometrical construction of your physical structure for this project.
<table>
</table>
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.}}
</table>
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.
<table>
</table>
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.
<table>
<p> </p>
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