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| − | {{projectinfo|Tutorial|Simulating a Monopole Antenna Interacting with a Human Head Model|FDTD601.png|In this project, a human head model is imported and its interaction with a monopole antenna is analyzed in EM.Tempo.|
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| − | *[[CubeCAD]]
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| − | *STEP Model File
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| − | *CAD Import
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| − | *Lossy Dielectric
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| − | *Field Distribution
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| − | *Radiation Pattern
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| − | |All versions|{{download|http://www.emagtech.com|EM.Tempo Lesson 14|[[EM.Cube]] 14.10}} }}
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| − | ===What You Will Learn===
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| − | In this tutorial you will learn how to import external CAD models and transfer them to [[EM.Tempo]]. You will construct a physical structure with different types of materials.
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| − | ==Getting Started==
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| − | Open the [[EM.Cube]] application and switch to [[FDTD Module]]. Start a new project with the following attributes:
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| − | <div class="noprint" style="float:left;margin-right:10px">
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| − | {| border="1" class="wikitable"
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| − | |+ Starting [[Parameters]]
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| − | |-
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| − | ! Name
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| − | | [[FDTDLesson14]]
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| − | |-
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| − | ! Length Units
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| − | | Centimeters
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| − | |-
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| − | ! Frequency Units
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| − | | MHz
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| − | |-
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| − | ! Center Frequency
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| − | | 900MHz
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| − | |-
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| − | ! Bandwidth
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| − | | 1000MHz
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| − | |}
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| − | </div>
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| − |
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| − | <div class="noprint" style="clear:both"></div>
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| − | To construct the physical structure of this tutorial lesson, you need the two STEP CAD models files: "Humand_Head.STP" and "Radio.STP". You can download these model files from our [http://www.emagtech.com/content/project-file-download-repository File Repository]. In the first part of this tutorial lesson, you will import the handheld radio model. You will then add a monopole antenna to it and analyze it. In the second part, you will import the human head model, place it in front of the radio unit and simulate the combo structure.
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| − | == Defining the Materials & Importing the External Models ==
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| − | In the [[FDTD Module]], create the following material groups:
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| − | {| border="0"
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| − | |-
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| − | | valign="top"|
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| − | {| class="wikitable" style="text-align: center;"
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| − | |-
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| − | ! scope="col"| Group Name
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| − | ! scope="col"| Material Type
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| − | ! scope="col"| Color
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| − | ! scope="col"| Material Name
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| − | ! scope="col"| Material Properties
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| − | |-
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| − | ! scope="row"| PEC_1
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| − | | PEC
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| − | | Red
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| − | | N/A
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| − | | N/A
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| − | |-
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| − | ! scope="row"| Dielectric_1
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| − | | Dielectric_1
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| − | | Light Green
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| − | | Plastic
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| − | | ε<sub>r</sub> = 2.2, μ<sub>r</sub> = 1, σ = 0, σ<sub>m</sub> = 0
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| − | |-
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| − | ! scope="row"| Dielectric_2
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| − | | Dielectric_2
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| − | | Light Brown
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| − | | Flesh
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| − | | ε<sub>r</sub> = 65, μ<sub>r</sub> = 1, σ = 0.6S/m, σ<sub>m</sub> = 0
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| − | |}
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| − | To import the radio model, go to [[EM.Cube]]'s File Menu and select <b>Import...</b>. Window's Open Dialog opens up with the file type set to ".STP". Browse your folders to find the downloaded "Radio.STP" file. Select it and click the <b>Open</b> button. Three [[Solid Objects|solid objects]] appear in the project workspace of the [[CubeCAD]] Module:
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| − | * Solid_1: Metal washer
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| − | * Solid_2: Metal base of antenna
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| − | * Solid_3: Plastic box
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| − | {{Note|All the imported objects first appear in [[CubeCAD]], from which you can move them to various modules.}}
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| − | Move Solid_1 and Solid_2 from [[CubeCAD]] to the PEC_1 group in the [[FDTD Module]]. To do so, select each object and right-click to select <b>Move To → FDTD → PEC_1</b> from the contextual menu. Similarly, move Solid_3 from [[CubeCAD]] to the Dielectric_1 group in the [[FDTD Module]]. Activated the PEC_1 group and draw a vertical line of length 8.5cm with the LCS coordinates at (0, 0, 0). This places your monopole antenna at the top of the imported metal base object.
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| − | Define a lumped source and place it on Line_1 object with an offset of 0.5cm close to the metal base. Define a default Port Definition, a Far Field Radiation Pattern observable with an Angle Increment of 3° for both Theta and Phi angles. Also, define three principal field sensor planes: Sensor_1, Sensor_2 and Sensor_3 along Z, X and Y directions, respectively, all centered at (0, 0, 0).
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| − | <table>
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| − | <tr>
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| − | <td>
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| − | [[Image:FDTD581.png|thumb|360px|The imported radio model in CubeCAD.]]
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| − | </td>
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| − | <td>
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| − | [[Image:FDTD592.png|thumb|360px|The geometry of the monopole antenna with the imported radio model in EM.Tempo.]]
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| − | </td>
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| − | </tr>
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| − | </table>
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| − | In this part of the tutorial lesson, you will import the human head model form the CAD model file "Human_Head.STP". Follow the same procedure you used to import the radio unit to [[CubeCAD]]. Once you import the human head model as Solid_4 into [[CubeCAD]], move it to the Deielctric_2 group in the [[FDTD Module]]. Note that the human head model is placed next to the handheld radio unit. Define a additional field sensor observable called Sensor_4 in the Y direction and center it a (0, 15cm, 0) passing through the middle of the head model.
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| − | <table>
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| − | <tr>
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| − | <td>
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| − | [[Image:FDTD580.png|thumb|350px|The imported human head model in CubeCAD.]]
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| − | </td>
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| − | <td>
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| − | [[Image:FDTD591.png|thumb|350px|The geometry of the monopole antenna with the imported radio and human head models in the FDTD Module.]]
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| − | </td>
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| − | </tr>
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| − | </table>
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| − | == Generating the FDTD Mesh ==
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| − | [[Image:FDTD585.png|thumb|300px|The Advanced FDTD Mesh Settings dialog.]]
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| − | Open the FDTD Mesh Settings dialog and change two of the [[parameters]] the affect the mesh of curved surface and structures with fine details. The first parameter is in the section titled "Mesh Adaptation to Geometric Contours" and concerns the "Min Grid Spacing for Geometric Contours" specified as a "Fraction of Max Grid Spacing in Free Space". Change its value to 0.25. The second parameter is in the section titled "Absolute Minimum Grid Spacing". Set its value specified as a "Fraction of Max Grid Spacing in Free Space" to 0.05. With the default mesh density of 20 cells per effective wavelength generate and view the mesh of the radio unit. As you can see from the above figure, the curved edges of the plastic box and the curvature of the metal washer and antenna base have been adequately captured by the generated FDTD mesh.
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| − | <table>
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| − | <tr>
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| − | <td>
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| − | [[Image:FDTD584.png|thumb|500px|The FDTD Mesh Settings dialog.]]
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| − | </td>
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| − | </tr>
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| − | </table>
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| − | Also, note how close the ear is to the plastic box. This is why you had to set some additional [[parameters]] in the mesh settings dialog to make sure that the separation between the ear and the plastic box is maintained. In other words, the absolute minimum grid spacing must accommodate this very small distance. To better capture the curvature of the head in the mesh, click the <b>Advanced</b> button of the Mesh Settings Dialog, and in the Advanced Settings Dialog, set the "Curved Edge Angle Tolerance" to 10 degrees. Since this structure is fairly large, reduce the mesh density to 15 cells per effective wavelength. The resulting FDTD mesh will generate more than 9.2 million cells.
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| − | <table>
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| − | <tr>
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| − | <td>
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| − | [[Image:FDTD590.png|thumb|350px|The FDTD mesh of the imported radio and human head models in the FDTD Module.]]
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| − | </td>
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| − | <td>
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| − | [[Image:FDTD589.png|thumb|350px|Another view of the mesh of the imported radio and human head models in the FDTD Module.]]
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| − | </td>
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| − | </tr>
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| − | </table>
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| − | ==Running an FDTD Analysis of the Combo Structure==
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| − | Run an FDTD analysis of the combo radio and human head structure, preferably with [[EM.Cube]]'s GPU-accelerated simulation engine. If you don't have a good GPU card, use a multi-core CPU with many threads. Set the Power Threshold Level to -25dB and increase the maximum number of time steps to 20,000. At the end of the simulation, examine the field distributions on all four sensor planes.
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| − | <table>
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| − | <tr>
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| − | <td>
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| − | [[Image:FDTD602.png|thumb|360px|Electric field distribution on Sensor_1 plane with the human head model on dB scale.]]
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| − | </td>
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| − | <td>
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| − | [[Image:FDTD603.png|thumb| 360px |Magnetic field distribution on Sensor_1 plane with the human head model on dB scale.]]
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| − | </td>
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| − | </tr>
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| − | <tr>
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| − | <td>
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| − | [[Image:FDTD604.png|thumb| 360px |Electric field distribution on Sensor_2 plane with the human head model on dB scale.]]
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| − | </td>
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| − | <td>
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| − | [[Image:FDTD605.png|thumb| 360px |Magnetic field distribution on Sensor_2 plane with the human head model on dB scale.]]
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| − | </td>
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| − | </tr>
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| − | <tr>
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| − | <td>
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| − | [[Image:FDTD606.png|thumb| 360px |Electric field distribution on Sensor_3 plane with the human head model on dB scale.]]
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| − | </td>
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| − | <td>
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| − | [[Image:FDTD607.png|thumb| 360px |Magnetic field distribution on Sensor_3 plane with the human head model on dB scale.]]
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| − | </td>
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| − | </tr>
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| − | <tr>
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| − | <td>
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| − | [[Image:FDTD608.png|thumb| 360px |Electric field distribution on Sensor_4 plane with the human head model on linear scale.]]
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| − | </td>
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| − | <td>
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| − | [[Image:FDTD609.png|thumb| 360px |Magnetic field distribution on Sensor_4 plane with the human head model on linear scale.]]
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| − | </td>
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| − | </tr>
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| − | </table>
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| − | Visualize the 3D radiation pattern of the antenna and plot its S<sub>11</sub> parameter in EM.Grid. You can see from the figure below a sharp resonance at slightly above 1GHz.
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| − | <table>
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| − | <tr>
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| − | <td>
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| − | [[Image:FDTD601.png|thumb|400px|The 3D radiation pattern of the monopole antenna on the handheld radio unit and next to the human head model.]]
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| − | </td>
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| − | <td>
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| − | [[Image:FDTD600.png|thumb|450px|The graph of magnitude and phase of the S<sub>11</sub> parameter of the monopole antenna on the handheld radio unit and next to the human head model.]]
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| − | </td>
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| − | </tr>
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| − | </table>
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| − | Also plot the 2D polar pattern graphs in EM.Grid. See how the presence of the human head has made the radiation pattern of the monopole antenna highly directional.
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| − | <table>
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| − | <tr>
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| − | <td>
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| − | [[Image:FDTD610.png|thumb|350px|The 2D polar radiation pattern graph in the XY plane.]]
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| − | </td>
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| − | <td>
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| − | [[Image:FDTD611.png|thumb|350px|The 2D polar radiation pattern graph in the YZ plane.]]
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| − | </td>
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| − | <td>
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| − | [[Image:FDTD612.png|thumb|350px|The 2D polar radiation pattern graph in the ZX plane.]]
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| − | </td>
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| − | </tr>
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| − | </table>
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| − | {{FDTD Details}}
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| − | {{EMCUBE directory}}
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| − | [[EM.Cube | Back to EM.Cube Wiki Main Page]]
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