So, welcome back to this Ansys video course
on designing waveguides
using the student version of AEDT
and in the previous video,
we detailed the governing equations
of the rectangular waveguide
as well as the different propagating modes
that exists in it
and in this video,
we are going to create
a rectangular waveguide
based on an example problem
from the textbook reference
Microwave Engineering by David M. Pozar
and in the chapter
transmission lines and waveguides.
So, here's the problem statement.
Find the cutoff frequencies
of the first five propagating modes
of a Teflon-filled K-band rectangular waveguide.
Dimensions are A = 1.07 cm and B = 0.43 cm.
Relative permittivity and the dielectric loss
tangent of Teflon are 2.08 and 0.0004
respectively.
If you're new to the AEDT user interface
then I recommend go back to
the Intro to Ansys HFSS AIS course
and you can access it through the link
that's on the screen to the top right.
So, let's get started.
Here's the interface of the AEDT Student
version and has an empty project.
Insert an HFSS design, you do this by
selecting that icon in the Desktop ribbon area
and in the Project Manager window,
notice that the solution type of the Ansys HFSS
design is Terminal Network.
That's the default solution type.
We need a Driven Modal solution
to visualize the waveguide modes.
Now if you need to change the solution type,
just go, right mouse click on the HFSS design
name and select Solution Type.
Under the option select modal and click OK
and in that Draw tab ribbon area,
you also have an option to change
that model units.
Make sure that we have default units in mm
and in that same ribbon area, select Draw Box
and select some box vertices
first draw it in the XY plane
click and then draw in the +Z Direction
click
and in the model history tree window,
notice you have an object named Box1
and it's created with a vacuum as the material
under the solids category.
Go ahead and edit the dimensions of this box.
Double click on the create box option.
A pop-up box occurs, you can use variables
to define the dimensions of the box.
Simply using them as the coordinates
in the values column.
Assign the values
when there properties definition box
comes up.
Edit the dimensions as shown here.
Now click OK to accept the modifications
and use the keyboard shortcut
Ctrl+D to fit all the objects
in the modeler window.
So, here's a tip.
Use appropriate names,
it's good practice because it helps in identifying
the required objects, when the model geometry
contains more than
one or two similar type of objects.
Double click on the object Box1
and you open up the attributes dialog box
and rename it to WG_fill,
as it represents the waveguide fill.
Change the material.
Click on the cell next to the material attribute
and select edit,
select definition window pops up
and it contains the list of available materials
that are installed in AEDT.
search for a specific material by using
the search name option.
you can see two Teflon material definitions
are available.
But these materials, the relative permittivity
and conductivity definitions do not match
with what's in the example problem.
So it's a good thing AEDT
supports custom material definitions.
Go ahead select the Teflon material
and click on Clone Material
near the bottom of the dialog box.
In that pop-up window,
edit the name and the properties as shown
and then accept the material definition
and use it for the waveguide fill material.
Change the transparency to 0.8,
helps you to better visualize the fields.
click OK to accept the changes.
and so far we have created the waveguide
interior cavity filled with Teflon
and that's all we need to do.
By default HFSS treats everything exterior to
the simulation domain
as a perfect electrical conductor PEC,
unless of course the auto option is selected.
You don't need to create an exterior metal
housing for the waveguide.
Press F
and that switches to face selection mode.
Select the face at the origin
which is along the Z-axis
and if in your view that face is not up front,
you can always select the B key
and that will select the face behind it.
B stands for behind.
Right Mouse click and select
Assign Excitation > Port > select the Wave Port.
A window for the Wave Port properties pops up.
The example problem statement says
first five modes.
So, enter the number of excitation modes to 5,
click on next
and keep the dafaults and click finish.
For completeness but not always necessary
for this example go ahead and repeat the same
for the face on the X-axis maximum for port 2
and verify that you see the ports of the modes
listed under the Excitation folder
in the Project Manager window.
Go ahead, now let's add a solution setup.
Right Mouse click on the Analysis category,
select Add Solution Setup > Advance
and in the pop-up window,
set the single solution frequency to 15 GHz.
Keep all the other defaults.
For the maximum number of passes
and the Delta S convergence
and now click OK to accept these modifications.
A new window pops up
and to edit the frequency sweep
for the solution setup
ensure that the sweep type is interpolating
and set the stop frequency to 35 GHz,
enable save fields at the basis points
that visualize the fields at these frequencies.
Now click OK to accept the sweep.
Save the project.
Go to the Simulation tab and select Validate.
Now a pop-up window appears,
validating the necessary simulation steps
and again good practice
to check for simulation validation
prior to analyzing,
especially as you start to learn HFSS
and after a successful validation,
select Analyze All to start the analysis.
So, this completes the simulation of
a rectangular waveguide using the AEDT HFSS
and after the simulation is complete
find the cutoff frequencies and plot the fields.
Now if you're unsure how to do this,
watch the next video
and here will postprocess the simulation results
and show a different a variety of simulation
results, how to plot them
or to have a better understand and
visualize the waveguide mode propagations.
Thank you for watching this video
and to find more information on AEDT HFSS
or any of our ANSYS simulation tools,
please go to ansys.com/courses today.