{{projectinfo|Tutorial|Modeling A Patch Antenna Array|Tempo L4 Fig7BFig title.png|In this project, a finite-sized patch antenna array is constructed and analyzed in EM.Tempo, and its beam is shaped and steered.|
*Array Object
*Source Array
In this tutorial you will try out the third method from the above list and model finite-sized probe-fed patch array structure.
[[Image:Back_icon.png|30px]] '''[[EM.Tempo | Back to EM.Tempo Manual]]'''
[[Image:Back_icon.png|30px]] '''[[EM.Cube#EM.Tempo_Documentation | Back to EM.Tempo Tutorial Gateway]]'''
[[Image:Download2x.png|30px]] '''[http://www.emagtech.com/downloads/ProjectRepo/EMTempo_Lesson4.zip Download projects related to this tutorial lesson]'''
== Getting Started ==
== Building a Finite-Sized Array ==
To build the finite-sized 4 × 4 patch array, use the '''Probe-Fed Patch Array Wizard''' [[Image:ProbeFedPatchArrayWizardIcon.png]] button to create a default 2 × 2 patch array first. Then, open the variables dialog and change the values of the parameters "nx" and "ny" to 4.
<table>
</table>
Finally, graph the 2D Cartesian and polar radiation patterns of the patch array in the YZ plane in EM.Grid.
<table>
In the previous part of this lesson, we assumed the all the 16 patch elements were excited using identical lumped sources. In other words, the amplitudes and phases of all the 16 lumped sources were assumed to be equal, hence, a uniform weight distribution. [[EM.Tempo]] allows you to define different weights for individual elements of a source array. Open the property dialog of the lumped source LS_1 and click the button labeled {{key|Array Weights...}}. In the array weight dialog, the '''Distribution''' drop-down list gives a number of options: Uniform, Binomial, Chebyshev and Custom. Uniform distribution is the default option as you used in the previous part of this tutorial lesson. Now select "Binomial" for a radiation pattern with minimal side lobes. Close the array weights dialog and then close the lumped source dialog to return to the project workspace.
<table>
<tr>
<td>
[[Image:Tempo_L4_Fig11a.png|thumb|480px|The Array Weights... button in the property dialog of the lumped source showing an associated line array object.
]]
</td>
</tr>
</table>
<table>
</table>
Next, visualize the 3D radiation pattern of the array. The directivity of the 4 × 4 patch array has now reduced to D0 = 34.07, but the side lobe have has disappeared.
<table>
== Steering the Beam of the Finite-Sized Array ==
In the last part of this tutorial lesson, you will steer the beam of your patch antenna array. In order to steer the beam of an antenna array to the spherical angles (<i>θ</i>, <i>φ</i>), a two-dimensional phase progression among the array elements is required along the X and Y directions given by the following equations:
<math>\Psi_x = -\frac{2\pi S_x}{\lambda_0} \sin\theta \cos\phi</math>
<math>\Psi_y = -\frac{2\pi S_y}{\lambda_0} \sin\theta \sin\phi</math>
where <i>S<sub>x</sub></i> and <i>S<sub>y</sub></i> are the element spacing along the X and Y directions, respectively. In this project, S<sub>x</sub> = S<sub>y</sub> = λ<sub>0</sub>/2. The phase progression is therefore given by:
<math>\Psi_x = - \pi \sin\theta \cos\phi</math>
<math>\Psi_y = - \pi \sin\theta \sin\phi</math>
In order to steer the array beam to <i>θ </i> = <i>φ </i> = +45°, you need phase progressions equal to Ψ<sub>x</sub> = Ψ<sub>y</sub> = -90° that is equal phase progression along both X and Y directions.
<table>
</table>
Run a new FDTD analysis of your beam-steered antenna array and visualize its 3D far-field radiation pattern. Note that the linear-scale direcitivity directivity of the steered beam has reduced to D0 = 41.4546.
<table>
<tr>
<td>
[[Image:Tempo L4 Fig23.png|thumb|480px600px|Specifying the custom Phi-plane in the radiation pattern dialog.]]
</td>
</tr>
</table>
Open the Data Manager and plot both of the data files "FF_1_PATTERN_Cart_Custom" and "FF_1_PATTERN_Polar_Custom" data files in EM.Grid.
<table>
<p> </p>
[[Image:Top_icon.png|30px]] '''[[#What_You_Will_Learn | Back to the Top of the Page]]''' [[Image:Back_icon.png|40px30px]] '''[[EM.Cube#EM.Tempo_Tutorial_Lessons Tempo_Documentation | Back to EM.Tempo Tutorial Gateway]]'''