{{projectinfo|Tutorial|Modeling A Probe-Fed Microstrip Patch Antenna|Tempo L3 Fig title.png|In this project, a probe-fed rectangular patch antenna is modeled and analyzed in EM.Tempo.|
*Domain Settings
*Variables
*Parametric Sweep
*Cartesian Graph
|All versions|{{download|http://www.emagtech.com/downloads/ProjectRepo/EMTempo_Lesson4EMTempo_Lesson3.zip EMTempo_Lesson4EMTempo_Lesson3}} }}
== What You Will Learn ==
In this tutorial you will use a wizard to build and analyze a probe-fed rectangular patch antenna on a finite-sized conductor-backed dielectric substrate. You will also learn how to use variables and run a parametric sweep simulation.
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== Getting Started ==
== Creating the Patch Antenna Geometry ==
As you did in the first tutorial lesson, you will use a wizard in this project to build the geometry of a rectangular patch antenna. Click on the <b>Probe-Fed Patch Wizard</b> [[Image:ProbeFedPatchWizardIcon.png]] button of the Wizard Toolbar or select the menu item '''Tools → Antenna Wizards → Probe-Fed Patch Antenna'''.
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The dimensions of the constituent objects have been parameterized. Open the variables dialog to see a list of the variables and their definitions. The initial value of the variable "sub_size" is 92.3976. This indicates the dielectric substrate is 92.3976mm × 92.3976mm × 1.5mm. Click the Edit button of the dialog to open the {{key|Edit}} Variable dialog. Replace this value by 150 in the box labeled '''Definition'''. Close this dialog to return to the variable dialog and check out the new value you just changed.
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<td> [[Image:Tempo_L3_Fig3_150mm.png|thumb|480px|Editing variable called "sub_size".]] </td>
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You can also see from the variables dialog that the dielectric substrate (represented by a box of dimensions 150mm × 150mm × 1.5mm) has a relative permittivity ε<sub>r</sub> = 2.2 and a thickness h = 1.5mm. A short vertical line called "Feed" is placed underneath the patch and is completely embedded in the substrate. This line object serves as the probe feed of the patch antenna and is associated with a lumped source called "LS_1". There is also a far-field radiation pattern observable with the default theta and phi angle increments of 5° as well as a port definition with a reference port impedance of 50Ω. Also, note that the metallic patch is a square with its side dimensions set equal to len = 0.48λ<sub>d</sub>, where λ<sub>d</sub> is the effective dielectric wavelength.
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<td> [[Image:Tempo_L3_Fig3next.png|thumb|480px|EM.Tempo's variables dialog.]] </td>
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== Defining a Near-Field Sensor Observable ==
== Running the FDTD Simulation & Visualizing the Results ==
At this time, your project is ready for FDTD simulation. Note that your antenna involves a very thin substrate layer. This requires a high resolution mesh to correctly represent the substrate thickness. The wizard automatically sets the mesh density to 40 cells/λ<sub>eff</sub>. The fraction of the absolute minimum grid spacing to maximum grid spacing in the free space has been set to 0.05. The Note that the Mesh settings dialog also provides a button labeled {{key|High Precision Mesh Settings}} that adjusts most of these parameters. The wizard's mesh settings for this particular geometry are even more demanding than the "high precision mesh settings''.
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The figures below show the theta and phi components of the 3D radiation pattern as well as the total radiation pattern plot. Note that the directivity of the antenna is computed to be D0 = 6.25242.
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<td> [[Image:Tempo L3 Fig8.png|thumb|left|480px540px|The total electric field distribution on the patch plane.]] </td>
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<td> [[Image:Tempo L3 Fig9.png|thumb|left|480px540px|The total magnetic field distribution on the patch plane.]] </td>
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Run a new FDTD analysis of your patch and plot its S11 parameter in EM.Grid. Note that the new probe location provide a better return loss and a deeper resonance notch.
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The radiation pattern of the patch doesnand the the electric and magnetic field levels don't change much with the location of its probe feed. However, the electric and magnetic field levels increase at the edges of the patch as seen in the figure below:
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Next, open the property dialog of the object "Patch_ANCHOR". Replace the value of the box labeled "Y "Outer DimensionSize" with "wid" and click the {{key|OK}} button of the property dialog to return to the project workspace. Note that width of the patch has slightly increased and it is no longer a square.
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The sweep variables list is initially empty. On the left side of this dialog, you see a list of all the available independent variables. Select "wid" from the left table and used the {{key|-->}} button to move it to the right table. Another dialog titled "Sweep Variable" opens up. You have to set the start, stop and step values of your sweep variable. By default, the sweep variable is of uniform type. Enter 70, 100, and 10 for start, stop and step values, respectively. This will create a value list of {70, 80, 90, 100}. Close the sweep variable dialog and then close the sweep settings dialog to return to the simulation run dialog.
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<td> [[Image:Tempo_L3_Fig19_new.png|thumb|700px|Parametric sweep settings dialog.]] </td>
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<td> [[Image:Tempo_L3_Fig19_newTempo_L3_Fig19.png|thumb|700px|Selecting variable "wid" in Parametric sweep settings dialog.]] </td>
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Run the sweep simulation. It may take a while as a total of four individual FDTD simulations must be completed. At each simulation, [[EM.Tempo]] generates a new mesh of the modified structure and passes it to the engine. At the end of the parametric sweep, open the data manager and plot the data file "DP_S11.CPX" in EM.Grid. You should see a graph like the following:
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<td> [[Image:Tempo L3 Fig22.png|thumb|480px600px|The total electric field distribution on the patch plane with a patch width of 100mm.]] </td>
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