In radio and telecommunications a dipole antenna is the simplest and most widely used class of antenna. There are multiple types of dipole antennas - the simplest ones you can simulate using CENOS Antenna Design Templates, but for more complex ones (such as loop or folded dipole) Geometry Editor can be used!
In this guide we will take a look at how to build a complete folded dipole antenna simulation from scratch in CENOS Antenna Design app, using its built-in geometry editor, FreeCAD.
Before we can actually start building our simulation, we need to first prepare our case - choose the way we will build our geometry, and save the case.
You have three options from which to choose - Templates, Import CAD (if you have your own CAD file ready) and Geometry Editor.
For this example we will choose Geometry Editor and build our folded dipole geometry ourselves.
At this point you need to save the case, otherwise if you try to open FreeCAD, CENOS will not let you move forward.
Once the case is saved, click the Play icon to open FreeCAD - CENOS geometry editor.
In FreeCAD we have all the possibilities to build our antenna geometry, and we are going to do just that.
In this Geometry creation section we will cover all main points you need to complete to build your own patch antenna geometry manually.
First thing we need to do is to draw the sketch of our wire. In Sketch workbench create a sketch and draw the wire outline.
For dipole antenna feed definition we can use a simple curved uniform port instead of a more complex SMA connector.
To create separate surface for our port, draw a separate line in the sketch where you want to put your feed!
Once the sketch is created, add wire thickness to the sketch to build the actual wire geometry.
With wire creation you have finished your geometry creation!
Once you have finished the geometry, you need to send the mesh to CENOS. To do that:
Select all final objects in the tree view.
Click Geometry to CENOS.
As geometry is being sent to CENOS, FreeCAD study will be automatically saved in the simulation folder, so you can close it.
If during the calculation you get a message about meshing problems, you will need to manually mesh your antenna in FreeCAD. You can also mesh it manually already when building your geometry (while still in FreeCAD) in case you want more control over your simulation.
Once the geometry is finished and sent to CENOS, you need to define your geometry before defining the physics on it.
Essentially you need to clarify which part of your geometry is the dielectric, which is the port etc., in other words, define roles for parts of your geometry.
Before you define roles, you need to select what kind of antenna you have - Microstrip, Wire or Other.
For this example we choose Wire antenna type.
Now you need to define surface and volume roles for your wire and port.
If you define Wire as the full wire volume, it will overlap with the Port surface and affect the results. For Wire definition choose faces and select all faces except Port!
When roles are assigned, GO TO PHYSICS button will become active - click it to move to the Physics definition!
In physics you need to define the physical parameters of your simulation, which include frequencies, material definitions and boundary conditions.
In SIMULATION CONTROL you define either a single frequency or a frequency sweep.
Wire and Free space is already predefined for you, so you don't need to worry about these parts at all!
Boundaries or boundary conditions have also been predefined:
Feed surface → Uniform Port (with default 50 Ohm Impedance)
Wire → Perfect Electric Conductor
Free space surface → Radiation Boundary
Once all physical parameters are filled, RUN button will become active and you will be able to run the simulation!
When calculation is done, results will automatically open in a new window. Congratulations, you have successfully finished a folded dipole antenna simulation!