{{projectinfo|Tutorial| Analyzing A CPW-Fed Folded Dipole Slot Antenna|Picasso L8 Fig title.png|In this project, you will build a slot-based planar structure and excite it using a pair of coupled scattering wave ports.|
*[[Building_Geometrical_Constructions_in_CubeCAD | CubeCAD]]
*Slot Trace
*Coplanar Waveguide
In this tutorial you will learn how to construct and simulate slot structures. You will define coupled ports to model coplanar waveguide (CPW) structures.
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== Getting Started ==
== Creating the Base One-Port Coplanar Waveguide Line ==
Click on the <b>CPW Wizard</b> button [[Image:CPWWizardIconx.png]] button of the Wizard Toolbar or select the menu item '''Tools → Transmission Line Wizards → Coplanar Waveguide'''.
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| 0.0015*to_meters
| 1.2
|-
| feed_len
| 0.5*center_len
| 30
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#Feed_2
The objects wizards create created are not only highly parameterized, but they are also usually linked to one another. This means that you can move them or rotate them together without affecting their parameterization. But they are rules to follow. The object named "ANCHOR" is the one which you should translate or rotate. Most other objects initially created by a wizard are linked to the anchor and follow its translation or rotation.
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== Drawing the Additional Slot Segments ==
Open the variables dialog again and change the definition of variable "center_len" to 2 as shown below. This will turn the objects "ANCHOR" and "Slot_2" into small joint squares.
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Y11: 0.020560 +0.003110j
Keep in mind that since [[EM.Picasso]] models slot traces as perfect magnetic conductors (PMC), the electric surface current distribution is zero everywhere. Therefore, under the current distribution node "CD_1" in teh the navigation tree, you should look at the magnetic current distribution plots instead. Note that the magnetic current density has units of V/m, which is the same as that of electric field.
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At the end of the sweep simulation, graph three data files: “S11_RationalFit.CPX”, “Z11_RationalFit.CPX” and “VSWR_RationalFit.DAT” in EM.Grid. You will see that around 1.65GHz, the magnitude of S<sub>11</sub> (return loss) dips into a deep minimum representing a very good impedance match. Also note that the slot antenna features a 10-dB return loss bandwidth of more than 330MHz.
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The real and imaginary parts of the input impedance are initially plotted on two separate graphs. You can merge them into a single graph by selecting the menu item '''Edit → Combine Plots''' from the "Edit Menu" of EM.Grid.You can track the data points on EM.Grid plots. In the impedance graph, click on the "Tracker" tab of the left side bar. As you move Move the mouse on the Z11 graph, you can and read the value of the horizontal axis (frequency) and the corresponding value of the real and imaginary parts of Z11-parameter in the settings panel. You can see that around 1.65GHz, the imaginary part of Z<sub>11</sub> (<i>i.e.</i> input reactance) vanishes and the antenna resonates.
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In Finally, move the mouse to the bottom of the the voltage standing wave ratio (VSWR) minima in the graph, click on the "Edit Plots" tab of the left side bar and check the box labeled '''Show Minima'''. A small tooltip appears on the graph showing It shows that the minimum VSWR to be is 1.068. Next, click on the "Edit Graph" tab of the left side panel. You can modify many parameters related to the appearance of the graph from this panel. You can change the margins on the four sides of the graph box and also change the format of the axis labels.
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[[Image:Picasso L8 Fig12.png|thumb|left|600px|The graph of the voltage standing wave ratio (VSWR) of the folded slot antenna.]]
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Alternatively, in the data manager, you can "view" the contents of the data file “VSWR_RationalFit.DAT” in the spreadsheet as shown below.
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[[Image:Picasso_L8_Fig12view.png|thumb|left|600px|The contents of the data file "VSWR_RationalFit.DAT" shown in data manager's spreadsheet...]]
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