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*Radiation Pattern
*Field Sensor Observable
*EM.Grid
*Cartesian and Polar Graphs
|All versions|{{download|http://www.emagtech.com/downloads/ProjectRepo/EMTempo_Lesson1.zip EMTempo_Lesson1}} }}
{{Note|We strongly recommend that you read through the first few tutorials and study them carefully before setting up your own projects.}}
 
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== Getting Started ==
Open the [[EM.Cube]] application by double-clicking on its icon on your desktop. By default, [[EM.Cube]] opens a blank project with the name “UntitledProj1” “UntitledProj0” in its [[Building_Geometrical_Constructions_in_CubeCAD | CubeCAD]] Module. You can start drawing objects and build up your physical structure right away. Or you can initiate a new project by selecting the <b>New</b> [[Image:fdtd_newb.png]] button of the System Toolbar or using the keyboard shortcut {{key|Ctrl+N}}. This opens up the '''New Project Dialog''', where you can enter a title for your new project and set its path on your hard drive. From the same dialog, you can also set the project’s length units, frequency units, center frequency and bandwidth.
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Click the {{key|Create}} button [[Image:WireDipoleIconx.png]] of the dialog to accept the settings. A new project folder with your given name is immediately created at your specified path.
To navigate to [[EM.Tempo]], simply select its icon from the '''Module Toolbar''' on the left side of the screen. Selecting the module icon changes the contents of the navigation tree to reflect the types of objects supported by the current module.
== Creating the Dipole Antenna Geometry ==
Click on the <b>Wire Dipole Wizard</b> [[Image:WireDipoleIconx.png]] button of the Wizard Toolbar or select the menu item '''Tools &rarr; Antenna Wizards &rarr; Wire Dipole Antenna'''.
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The geometry of a dipole antenna appears at the center of the project workspace. A close look at the physical structure reveals that it consists of two thin vertical cylinders connected through a short vertical line at the center. In the navigation tree on the left, you see three objects listed under a perfect electric conductor (PEC) material group called "DIPOLE":
# Feed_Line_ANCHORANCHOR (Feed Line)
# Dipole_Arm_1
# Dipole_Arm_2
== Examining the Length of the Dipole ==
The geometry of the dipole antenna created by the wizard is fully parameterized. The objective of this tutorial lesson is to teach the basics of running a simulation rather than parameterizing a geometrical construction. Therefore, we will not get into the details of defining variables at this point. Note that at the center frequency <i>f<sub>c</sub></i> = 1GHz, the operating wavelength is:
<math> \lambda_0 = \frac{c}{f} = \frac{3\times 10^8}{1 \times 10^9} = 0.3m = 300mm </math>
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<td> [[Image:Tempo L1 Fig8.png|thumb|left|480px600px|EM.Tempo's radiation pattern dialog.]] </td>
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== Examining the FDTD Mesh ==
[[EM.Tempo]] generates a “staircase” Yee mesh of your physical structure. To be able to capture the details of your dipole's very fine cylindrical arms, the mesh should have adequate resolution. [[EM.Tempo]]’s default “Adaptive” FDTD mesh generator exactly does that. To view the mesh, click the <b>Show/Generate Mesh</b> [[Image:fdtd_meshshow.png]] button of the Simulate Toolbar or alternatively use the keyboard shortcut {{key|Ctrl+M}}. The resolution of the mesh is determined by its '''Mesh Density''' expressed in effective wavelength. EM.Tempo's default mesh density of is 20 cells/&lambda;<sub>eff</sub>. However, the wizard automatically set sets the mesh density to 50 cells/&lambda;<sub>eff</sub> for this particular structure. Open the FDTD Mesh Settings dialog by clicking the <b>Mesh Settings</b> [[Image:fdtd_meshsettings.png]] button of Simulate Toolbar or using the keyboard shortcut {{key|Ctrl+G}}. The FDTD Mesh Settings dialog offers a large number of parameters that can be used to fine-tune the Yee mesh to better approximate and represent your physical structure.
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Before you run your first FDTD simulation in [[EM.Tempo]], let’s take a closer look at the FDTD simulation engine’s settings. Click the {{key|Settings}} button next to the “Select Engine” drop-down list to bring up the FDTD Engine Settings dialog. The convergence section ("Termination Criterion") of this dialog offers three criteria for terminating the FDTD time marching scheme. The first one is a <b>Power Threshold</b>, which normally has a default value of -30dB. The second one is a maximum number of steps (<b>Maximum Number of No. Time Steps</b>), which normally has a default value of 10,000. The third option is labeled “Both”, which means that both of the above termination criteria will be considered until one of them is met. For this particular structure, the wizard set the power threshold equal to -50dB 40dB and the maximum number of time steps to 20,000.
{{Note|For highly resonant structures, it is recommended that you establish a much more demanding convergence criterion with a lower power threshold value and a larger number of time steps.}}
== Plotting Scattering and Impedance Parameters ==
A list of all the 2D output data files generated at the end of a simulation can be viewed in [[EM.Tempo]]’s Data Manager. To open this dialog, click the <b>Data Manager</b> [[Image:fdtd_datamanagerb.png]] button of Simulate Toolbar, or use the keyboard shortcut {{key|Ctrl+D}}, or select the menu item '''Simulate &rarr; Data Manager'''. Select the file "DP_S11.CPX" from the list by clicking on its name and highlighting its row in the table. Click the {{key|Plot}} button of the dialog to open EM.Grid, [[EM.Cube]]'s plotting utility. A Cartesian PyPlot graph window pops up that shows the magnitude and phase of the S11 parameter. If you move the mouse around the graph, you can read the values of the graph on the Status Bar of the graph window. The figure below shows that the dip of the plot is at 977MHz with a value of -33.4dB
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[[Image:Tempo L1 Fig17.png|thumb|480px720px|left|The data manager dialog.]]
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[[Image:Tempo L1 Fig18.png|thumb|480px|left|Plot of the return loss (S11 parameter) in EM.Grid.]]
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Next, select the file "DP_Z11.CPX" from the list and plot it. This time EM.Grid the graph shows the real and imaginary parts of the Z11 parameter. It can be seen that at 977MHz, the input resistance of the dipole is 73.75&Omega;.
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[[Image:Tempo L1 Fig19.png|thumb|480px|left|Plot of the input impedance (Z11 parameter) in EM.Grid.]]
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You can see from the legend box of the plot that the directivity of your dipole is computed to be D0 = 1.624632.
== Plotting the 2D Radiation Pattern Graphs ==
[[EM.Tempo]]'s data manager also contains a list of 2D radiation pattern graphs of both Cartesian and polar types. Click the <b>Data Manager</b> [[Image:fdtd_datamanagerb.png]] button of Simulate Toolbar and plot the two files “FF_1_PATTERN_Cart_YZ.DAT” and “FF_1_PATTERN_Polar_YZ.ANG”. Note that you can make multiple file selections using '''Shift''' and '''Ctrl''' keys. Click the {{key|Plot}} button of the Data Manager dialog to plot both files in EM.Grid.
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