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{{projectinfo|Tutorial| Optimizing A Microstrip Patch Antenna Design|Picasso L2 L10 Fig title.png|In this project, you will use one of EM.Cube's optimziers to design a patch antenna with a recessed microstrip feed line.|

Click on Follow a similar procedure as in Tutorial Lesson 2 and use the <b>Microstrip-Fed Patch Wizard</b> button of the Wizard Toolbar or select the menu item '''Tools &rarr; Antenna Wizards &rarr; Microstrip-Fed Patch Antenna'''. A dialog pops up asking you if you would like a patch design with a recessed feed. This time, answer "Yes" and let the wizard draw to create the parameterized geometry of the a patch antenna with the a recessed feed.

The figure below shows == Defining the planar mesh of your antenna structure with a mesh density of 30 Cells/&lambda;_eff: <table><tr><td> [[Image:Picasso L2 Fig1A.png|thumb|left|640px|The planar mesh of the patch antenna geometry with the recessed feed.]] </td></tr></table>Design Objective ==

== Running a Frequency Sweep In this project, you will fix the side dimensions of the Resonant Patch Antenna ==patch ("patch_len"), and will optimize the two feed variables: "recess_dep" and "recess_wid". But first you need to define a design objective for your project. The goal here is to achieve a good impedance match by varying the design variables. A return loss of -20dB typically represents a very good impedance match.

Open To define a design objective, click on the simulation run dialog and select '''Frequency SweepObjectives''' from [[File: Objective icon.png]] button of the drop-down list labeled Simulate Toolbar or select the menu item '''Simulation ModeSimulate &rarr; Objectives...'''[[EM.Cube]]'s Objectives dialog opens up, which is initially empty.

<td> [[Image:Picasso L2 L10 Fig4.png|thumb|left|480px|Setting frequency sweep as the simulation mode in EM.Picassocube's run Objective dialoginitially being empty.]] </td>

Click the {{key|Settings}} '''Add''' button next to of this drop-down list dialog to open "Add Objective" dialog. At the Frequency Sweep Settings bottom of this dialogyou will see a list of [[EM. The default frequency sweep type is Cube]]'''Uniform''', which you keep intacts available standard output parameters. Enter 2.15GHz and 2.65GHz The contents of this list vary depending on the observables you have already defined for your project. Since the start and stop frequencieswizard created a port definition for this project, respectively, and keep the you will see a number of frequency samples at standard output parameters related to the default value of 11S/Z/Y parameters. A design objective is defined as a logical statement:

<table><tr><td> [[Image:Picasso L2 Fig5.png|thumb|left|480px|EM.Picasso's frequency sweep settings dialog.]] </td></tr></table>'expression_1'' ''logical operator'' ''expression_2''

Close this dialog to return to the run dialog The first and click second expressions can be any mathematical expression involving the {{key|Run}} key to start the frequency sweepstandard output parameters, variables, Python functions, <i>etc</i>. After the completion of the sweep simulationThe logical operators are "==", open the data manager and plot the data files "S11_Sweep.CPX<", "<=", ">", ">=" and "Z11_Sweep_CPX!=" in EM(Not Equal To).Grid. Note that If you can make multiple file selections for plotting using set the {{key|Ctrl}} or {{key|Shift}} keys. <table><tr><td> [[Image:Picasso L2 Fig6.png|thumb|left|480px|Plots mouse focus at one of the magnitude expression boxes and phase of then double-click on the S₁₁ parameter name of one of the patch antenna output parameters in the list, it will be inserted in that box. Set up the following design objective as a function of frequency.]] </td></tr></table>shown in the figure below:

With [[EM.Picasso]], you can also perform an adaptive frequency sweep of your physical structure. This sweep starts with a few frequency samples in the beginning and then inserts more frequency samples in between and uses a rational function interpolation to achieve a smooth frequency response. Open the frequency sweep settings dialog again and this time choose the radio button '''Adaptive''' for the sweep type. Accept the default values of the adaptive sweep parameters and run and new adaptive frequency sweep simulation of your planar structure. The program may give a warning that during the adaptive sweep, current distribution and far-field radiation pattern data will not be produced. Ignore the warning and continue. Also, after a number of sweep iterations, the program may pop up a message saying the convergence criterion hasn't been met and will ask you whether to continue the sweep process. <u>In that case, reply "No" and stop the sweep</u>. Too many adaptive sweep iterations may sometime lead to spurious spikes in the frequency response. ---

<td> [[Image:Picasso L2 Fig8L10 Fig5.png|thumb|left|480px|Plots of Defining a new design objective in the magnitude and phase of the S₁₁ parameter at the end of an adaptive frequency sweep"Add Objective" dialog.]] </td>

<td> [[Image:Picasso L2 Fig9L10 Fig6.png|thumb|left|480px|Plots of the real and imaginary parts of the Z₁₁ parameter at EM.cube's Objective dialog showing the end of an adaptive frequency sweepnewly defined design objective.]] </td>

== Running a Parametric Sweep of Setting Up the Feed Recess Depth Optimization Process ==

At this time, you are going to vary the depth of the feed recess to see if it improves the return loss (|S11|). Open the simulation run dialog and select '''Parametric SweepOptimization''' as the simulation mode. You will notice a red box next to from the drop-down list. This means that you are not ready to run a simulation because some parameters havenlabeled '''Simulation Mode'''t been set yet.

<td> [[Image:Picasso L2 Fig12L10 Fig7.png|thumb|left|480px|Setting parametric sweep optimization as the simulation mode in EM.Picasso's run dialog.]] </td>

Click the {{key|Settings}} button next to the '''Simulation ModeSettings''' button next to this drop-down list to open the Parametric Sweep Optimization Settings dialog.

<td> [[Image:Picasso L2 Fig13L10 Fig8.png|thumb|left|720px|EM.Picasso's parametric sweep optimization settings dialogbefore designating the optimization variables.]] </td>

On Keep the default optimization '''Algorithm Type''', which is "Powell's Method". Next, you need to define the optimization variables. Similar to the case of a parametric sweep, on the left side of the dialog you will see a list of all the available independent variables already defined in your project. Select and highlight "recess_dep" and click the right arrow {{key|-->}} button in the middle of the dialog to move the selected variable to the '''Sweep Optimization Variables''' list on the right. A new dialog titled "Edit Sweep Optimization Variable" opens up. Accept the '''Uniform''' variable type Enter 2 and enter 2, 16, 2, for the start, stop minimum and step maximum values of the sweep variable, respectively. This will create a list Keep the default '''Variable Precision''' value of sweep variable values: {2, 4, 6, .0.1.Similarly, 14move "recess_wid" to the optimization variables table and enter 1 and 8 for its minimum and maximum values, 16}respectively.

<td> [[Image:Picasso L2 Fig14L10 Fig9.png|thumb|left|480px|Setting Defining the bounds and number of samples the optimization variable "recess_dep".]] </td><td> [[Image:Picasso L10 Fig9A.png|thumb|left|480px|Defining the bounds of the sweep optimization variable"recess_wid".]] </td>

Close this dialog and return to Back in the parametric sweep optimization settings dialog. You , you will see the specifications of the sweep variable two optimization variables in the table on the right. Set the value of '''Max Error''' equal to 0.1. This is used for the convergence of the objective function or error function. You can see from the figure below that the error function or "goal" has been defined by the mathematical expression:

<table><tr><td> [[Image:Picasso L2 Fig16.png|thumb(20*log10(S11M)) - (-20) |left|480px|Plots of the magnitude and phase of the S₁₁ parameter of the patch antenna as a function of the feed recess depth at f = 2.4GHz.]] </td></tr></table>

== Running a Parametric Sweep of the Feed Recess Width == Open the variable dialog and change the value of the variable "recess_dep" to 14mm. ----

<td> [[Image:Picasso L2 Fig17L10 Fig10.png|thumb|left|480px720px|Adjusting to The optimization settings dialog after designating the optimal value of the feed recess depthoptimization variables.]] </td>

Next, you are going to vary == Running the width Optimization of the feed recess to see how far you can improve the return loss (|S11|). Open the simulation run dialog and then the parametric sweep settings dialog. Select and highlight "recess_dep" in the sweep variables table on the right side of the dialog. Click the left arrow {{key|<--}} button in the middle of the dialog to move the selected sweep variable back to the '''Independent Variables''' list on the left. Now, select "recess_wid" from the left table and move it to the right table to make it the active sweep variable. In the "Edit Sweep Variable" dialog, accept the '''Uniform''' variable type and enter 1, 8, 1, for the start, stop and step values of the sweep variable, respectively. This will create a list of sweep variable values. Return to the parametric sweep settings dialog as shown in the figure below. Patch Antenna ==

<table><tr><td> [[Image:Picasso L2 Fig18Run the simulation and wait until the optimization algorithm converges.png|thumb|left|720px|The parametric sweep settings dialog showing "recess_wid" as Note that sometimes the active sweep variableoptimization process may never converge.This means that the goal you have set for your optimization might never be achieved within the defined range of the optimization variables. In that case, the optimization algorithm will complete the specified maximum number of iterations and will exit the loop. If the optimization is successful, [[EM.Cube]] </td></tr></table>automatically changes the values of the optimization variables and sets them equal to their optimal values. In this project, the Powell optimization algorithm yields the following optimal values for the designated design variables:

Run the new parametric sweep and then plot the data file {| class="S11_Sweep.CPXwikitable" in EM.Grid. Note that the return loss is minimized for a value of |-! scope="col"| Design Variable Name! scope="col"| Optimal Value|-| recess_dep between 2mm and 3mm| 13.1384|-| recess_wid| 2. 02129 |}

<td> [[Image:Picasso L2 Fig19L10 Fig11.png|thumb|left|480px550px|Plots of The variables dialog showing the magnitude and phase optimal values of the S₁₁ parameter of the patch antenna as a function of the feed recess width (design variables "recess_dep = 14mm) at f = 2.4GHz" and "recess_wid".]] </td>

<td> [[Image:Picasso L2 Fig20L10 Fig12.png|thumb|left|550px640px|The variables dialog showing the optimal values geometry of the design variables "recess_dep" and "recess_wid"optimized patch antenna with the recessed microstrip feed line.]] </td>

<table><tr><td> [[Image:Picasso L2 Fig21.png|thumb|left|640px|The geometry of To verify the outcome of your optimization process, run a '''Single-Frequency Analysis''' of your patch antenna structure with at the optimal recessed feedproject center frequency of fc = 2.]] </td></tr></table>4GHz. After the completion of the simulation, the output message window reports the port characteristics of your new optimized antenna:

Run a quick singleS11: -frequency PMOM analysis of the optimal structure0. At the end of the simulation, the port characteristics are reported as follows:060578 -0.077976j

S11(dB): 0-20.011933 +0.142894j109976

S11(dB)Z11: 43.781258 -166.869538894998j

Z11Y11: 490.134305 022288 +140.336804j003510j

Y11: 0As you can see from the value of the return loss, the specified design goal has been accomplished.018756 -0.005473j

The return loss has dramatically improved down <p>&nbsp;</p>[[Image:Top_icon.png|30px]] '''[[#What_You_Will_Learn | Back to -16.87dB. Visualize the current distribution and 3D radiation pattern Top of the antenna as shown in the figures below. Notice how the standing wave pattern has diminished on the microstrip feed line due to the improved impedance match. Page]]'''

<table><tr><td> [[Image:Picasso L2 Fig22.png|thumb|left|640px|The plot of total electric current (JTOT) distribution of the patch antenna.]] </td></tr></table> <table><tr><td> [[Image:Picasso L2 Fig23.png|thumb|left|640px|The 3D radiation pattern plot of the patch antenna.]] </td></tr></table> Finally, run an adaptive frequency sweep of your patch antenna with the optimal recessed feed over the frequency range [2GHz, 3GHz]. After the completion of the sweep simulation, open the data manager and plot the data files "S11_RationalFit.CPX" and "Z11_RationalFit.CPX" in EM.Grid. The graphs of the S and Z parameters are shown in the figures below. A very good resonance and impedance match is accomplished at 2.4GHz. <table><tr><td> [[Image:Picasso L2 Fig24.png|thumb|left|480px|Plots of the magnitude and phase of the S₁₁ parameter of the patch antenna with the optimal recessed feed.]] </td></tr></table> <table><tr><td> [[Image:Picasso L2 Fig25.png|thumb|left|480px|Plots of the real and imaginary parts of the Z₁₁ parameter of the patch antenna with the optimal recessed feed.]] </td></tr></table> <p>&nbsp;</p>[[Image:Back_icon.png|40px30px]] '''[[EM.Cube#EM.Picasso_Tutorial_Lessons Picasso_Documentation | Back to EM.Picasso Tutorial Gateway]]'''