And, welcome to this section of the
microstrip patch antenna array creation.
And in a previous section, we discussed
how to create a probe fed microstrip antenna
using the HFSS antenna toolkit.
And this model geometry and the analysis
set up, the excitation and the results
such as return loss and radiation pattern,
the gain. They were all automatically created
and ready for you to simulate.
In this video, we're going to design an 8x8
microstrip patch antenna array using
that same model.
So, let's get started
Go ahead, launch Ansys electronic desktop
and open up the single probe fed
microstrip antenna that was created
or go ahead and create a new one
from the toolkit.
Create a new HFSS model for the array,
one way of doing this is just to go to
the project manager window,
select that single element model,
copy and paste it into the project name
and you automatically generate
another instance of that model
in your project folder.
And rename that model to array
and you could call it FADDM for
finite array domain decomposition.
Now, highlight the model name
and right mouse click.
Again, select the solution type
and uncheck the "auto open" and you'll see
a large red radiating box in the modeler window
and that is an automatically created air box.
This is our unit cell for the array.
As in the array factor equation, the
finite array wizard assumes that each
element of the array is physically the same
with the same field pattern.
And the array is uniformly excited in magnitude.
Although, in HFSS you can add a phase
shift to the element
and that unit cell needs to have a
coupled boundary condition
to define the array. And since our unit cell
is rectangular, we can select the coupled faces
and use the lattice pair definition or
the auto identify option.
And if the unit cell is not rectangular,
define the coupled surfaces or boundaries
by explicitly defining the primary and
secondary surfaces.
And the coupled boundary that forces a
periodicity in the field that
corresponds to the periodicity of the array.
And it does this by mapping the fields
from the primary boundary
to the secondary boundary.
And these fields are identical to each other
with the exception of a potential phase shift.
And this phase shift is what is used
to enforce the progressive phase delay across
the entire array and that steers the beam.
And a couple boundary uses the U-V coordinate
system to determine the field mapping.
And the coupled pairs are defined on
opposite surfaces of the unit cell
and the secondary U-V coordinate system
should be a simple linear translation of that
primary U-V coordinate system.
And if done correctly, the distance between
each of the boundaries of the U-V
coordinate system
also corresponds to the distance
and the direction of that next
adjacent element in the array.
And creating the U-V coordinate system by
selecting two points and that first point
corresponds to the coordinate system's
origin and the second point defines that
the U-axis direction
and the phase delay between the couple
boundary pairs.
And in the phase delay tab, you can also
define the phase delay
in terms of an array scan angle
and determine the appropriate phase
delay to steer the beam.
So, let's go back to our model
and so we have a rectangular model,
we'll make it easy and we'll use that
auto identify lattice pair
to create the coupled surfaces.
Select the object air box and select
"assign boundary" -> "coupled"
"auto assign boundary". A dialog box
appears and select the XY-plane
and that's perpendicular to the lattice pair
and select okay. And now you see both the
primary and the secondary
pair appears along the y and the x-axes.
so let's go ahead and use a phase delay
between the elements by defining a scan angle.
Double mouse click on the "latticepair1"
and that will open up the lattice pair dialog box
and create a variable name "phi_scan" for the
phi delay and "theta_scan" for the theta delay.
And when you add a variable, the add
variable dialog box appears
so go ahead and use "0" as the default value.
Note the scan angle is automatically
repeated for the "latticepair2".
And we need to create an open region
and select the top and the bottom surface
of that air region, right mouse click
and assign a "radiation" boundary
Note, depending on your design you may also
want to use a perfectly matched layer, a PML.
Let's create the array, select "HFSS" ->
"model" -> "create array" and when the regular
array properties dialog box appears,
in the general tab you have the option
to specify the name of the array.
Check the array as visible and
"a" vector which is the y direction
and the boundary is the "latticepair1"
and select 8 for the size
for the "b" vector which is in the x direction
the boundary is the "latticepair2" and
select the size as 8.
Keep the padding cells to 1
and in the active cell tab, you can call out
all the elements as active or select off elements,
but we'll just keep it simple and
just select all active.
Select "apply" and close and now you'll see a
large 8x8 array.
Go ahead and set up your 2D and 3D
radiation spheres.
And for the array, the analysis setup is the same
as for the single element, only the
geometry has been changed.
Go ahead and analyze.
And when the simulation is completed,
go ahead and use the post processing
to set the magnitude and the phase
for each of the elements.
Select "HFSS" -> "toolkit" -> "finite array
beam angle" and let's keep the defaults for now
0 for boresight and check "calculate"
and "apply edit sources" and you're done.
and we could always verify whether the toolkit
put in the correct value
by right mouse click on "excitation",
select "edit sources"
and see what the values are set.
And go ahead and view the results
and the array radiation pattern depends
on many factors
such as the number of elements,
the distance between the elements,
the excitation amplitude of each element,
the phase of each element. So go ahead
and change these parameters and verify
the change in the radiation pattern.
and you can plot these radiation
patterns for different values
to visualize the beam steering.
Go ahead and compare the radiation
pattern of the array to that of a single element
and you clearly see that the gain
has increased significantly.
And don't forget to use the "compute
antenna parameter" feature
and you get that by right mouse clicking
on one of the far field setups
And in HFSS you can always plot the
radiation pattern
on the geometry to visualize the fields
and that is the advantage of using an
electromagnetic simulation tool
and not to mention the necessity of
considering the finiteness of the array
but both the near and the far fields.
And in this video, we created the antenna array
using a probe fed microstrip antenna element
that was already created in the previous model
and we used the antenna toolkit.
we used the finite array wizard and
created the 8x8 array
we created the couple lattice pair
using the auto identify option.
Thank you for watching and listening
and for additional Ansys learning
videos, visit our website
at www.ansys.com/courses today.