ANSYS EMC Plus Antenna in a Resonant Cavity

Hello, this is Ibrahim Nassar with OZEN Engineering. In this demo, we'll show you how to use the EMA3D and MHarness ANSYS tools to simulate an antenna inside a cavity and measure the electric field strength. This demo assumes previous knowledge in the ANSYS Discovery Geometry interface.

In this demo, we'll use the EMA3D2024R1 release. And we will start by opening a CAD file that has the geometry already created. So to open the geometry, let's go to File, then Open. And we're going to open this file, which is available in the EMA3D Open Examples.

This file, as you see, has this geometry, which is made out of faces. So the box is made out of faces and it has an opening on the top. And it has here a curve, which is an antenna. And the geometry is listed here. The first step in this simulation is to define the solution domain.

So to do that, we can go to the EMA3D tab and click on Domain. Then let's expand the time, the lattice, minimum, maximum, and the step size. Let's keep the stability margin at 15%. And let's change the minimum frequency to be 10 MHz and the maximum frequency to be 500 MHz.

This might adjust the stability margin, so let's bring it back to 15%. Now let's differentiate the two. So let's go to the EMA3D. We'll define the lattice. So the minimum X is - 420. The minimum Y is -420 as well. The minimum Z is - 1920. The max X is 1920. The maximum Y is also 1920 millimeters.

And the maximum Z is 420. And let's keep the step size to be 60 millimeters. So now as you see, we have this simulation domain that encloses the entire geometry. To save it, we click on the green checkmark. After the simulation domain is defined, the next step is to define basically the materials.

So let's go to the EMA3D tab and select Materials and let's select Isotropic. Let's define a new material by clicking on the Isotropic. Let's define a new material by clicking on these ellipses. And select the Local tab and click on New.

So this has created a new material called Isotropic 1. So let's double click on it. We can change the name here to be Aluminum. And let's expand General. And let's change the electric conductivity to be 1.2E 7. We can also give it a different color.

So let's click here and we select from these colors or click More Colors. And select the colors from this window. And here we can change the alpha which is the transparency of the geometry. And hit OK. Now we need to select the faces where we want to define the materials.

So we have different selection modes and let's select Faces here. Or surfaces. And we can select them one by one or create a rectangle to drag it. And select all the faces in this geometry. After that we click on the green check mark to save it.

So now we see the aluminum material is listed here and we can click here to show it or hide it. After we define the material. Now let's define a probe to measure the fields. To do that we go again to the EMA3D tab. And click on Fields. And let's select a boxed region to be the probe.

Here we can give it a name. And we have the option to select for the field type to be electric or magnetic. So in this case we want electric. And let's create the boxed region by expanding the bounds minimum and maximum. Or we can just basically drag and drop these arrows to change the size.

So let's define it here. And these minimum and maximum bounds. So let's select for the minimum X to be 540. The minimum Y to be 1080. The minimum Z to be - 360. The maximum X is 840. The maximum Y is also 380. And the maximum Z is - 60. So now as you see we define this boxed region here.

And underneath this aperture or opening in the box. To save it we click on the green checkmark. And as you see now it's listed under props. Now we will build the antenna by going to the M harness tab. And select cabling. And we want to define the antenna to be a conductor.

So this opens the properties panel window here as you see. Then we can select either line or point. So let's first select the antenna by selecting a line. And select the antenna wire. And after it's selected. You see there's two endpoints called U. So we select the point selection mode.

And select the lower end. So now let's define the conductor. By clicking on these ellipses. And let's select it to be one of the wires defined in the library. So we click on the library tab. And expand general. And bare wire. And let's select 16 gauge wire.

So this is defining the conductor for the wire. Now we want to define the termination for this wire. So we click expand terminations. And let's select click on these ellipses. And let's keep the termination to be a resistive boundary. But let's change it to 50 ohm.

By clicking the X it will be saved. And let's change the termination resistance to be a very small value. Let's call it 1E- 6. And now we can click on the green check mark. To save it. Now we see conductor 1 listed under the harness. And this completes the setup of the antenna.

Next we want to define a source to excite this antenna. So to do that we can go here. To the M harness tab. And click on pin excitations. And let's select pin voltage. We first select the line of the antenna. The wire. And then we select the point. Go to the point selection mode.

And select the end point of it. And now in this window we can select which conductor we want to excite. So in this case we only have one. Which is the conductor 1. And if you have different layers you can switch between them. So let's select conductor 1 and hit OK. Now we define the pin voltage.

To make it usable we have to define the signal. And let's in this example select a derivative of Gaussian. Let's keep all the settings the same. But let's change the alpha to be 1E- 18. And you can click on the FFT to see the FFT of the signal. And to save it we can click on the X checkmark.

Now you see the signal is available here. So we need basically to drag it and drop it on the pin voltage. To make it usable. Now the signal appears under the pin voltage excitation. And that will make it active. And the pin voltage is ready to use. Now everything is kind of set up.

And now we're going to create the mesh. To create the mesh basically just click on the meshing here. Whether you are in the M harness tab or in the EMA3D tab. So click the mesh. And now the geometry is meshed. And you see that the conductor is also meshed.

You can right click and select inverse visibility. To just view the mesh. And you can escape it. Now the mesh is created. We can start the solve. And again you can solve it whether you are in the EMA3D tab or the M harness tab. So we can click on start. And as you see we don't have any warnings.

Then we click on run to simulate. So this model is very small. And as you see it completes the simulation in a very short time. Now after the simulation is done. We can see domain and the results.

And we can see also field prop 1. Now we right click on field prop 1. And we have two options to post process the results basically. To compute. The two options are the compute field statistics or compute field averages. Compute field statistics calculates the field averages.

And also calculate the shield effectiveness. But shield effectiveness here is not a useful measure in this simulation problem. So we just going to select the compute field averages. Here you have the option to select the directions. So let's keep them all selected and hit OK.

And now we see the 2D plots are listed here. And their visualizations. And to show the results. We can right click on field prop 1. And select show. And now we see the E field strength. And it's for the given for the lower bound. Upper bound and the mean.

And you can do different type of post processing here. And adjustment to this plot. You can right click and say select configure the chart. And change the scale from log and give titles and everything. With that this concludes this demo. And thank you very much.