Hobbyist and low-cost antenna design software have been usually limited to basic theoretical calculations based on ideal EM equations that could be done on the back of the hand. It is only recently that full EM simulation has drifted down to the masses in a semi-affordable way. CENOS Antenna Design software is one of the few that fits into this bracket, especially for hobbyists and academics.
This is because they offer the ability to apply for a free license if you are an academic, hobbyist for non-commercial application. The antenna design software makes it possible to create complex microstrip antenna designs and do a full EM simulation across frequencies along with the calculation of 3D radiation patterns and frequency response.
CENOS was founded in 2017 by 3 PhDs in physics and mathematics who committed themselves to democratize simulation software by making it easy, affordable, and secure to use by every engineer. We believe the adoption of simulation should go beyond R&D centers of corporates and help engineers at production plants and small manufacturers to bring their engineering to the new level.
https://www.cenos-platform.com/about
The CENOS software is built on top of and is made possible by the use of Free Open Source Software (FOSS).
I will be using CENOS Antenna Desing version 1.1.2 but there is a newer version that I will be updating to soon. It is also Windows 10 only so far but I hope they release a Linux version so I can take full advantage of my server compute power.
Patch Antenna Design Template
When the software launches the user is prompted to either upload the antenna geometry or use a template. Since I am just testing the software for now I will be using the microstrip patch antenna design template to compare with my Matlab designed antenna that I had created previously. There is also a dipole antenna template that I might explore later.
The process is actually really simple for the template case. After installing the software open it up and select the template option. This will take you through the process of defining the geometry and the physical properties of the simulation.
Next, select the Patch Antenna option, you will then be able to define the various dimensions of the patch antenna as well as select if you want an inset to the feed.
I will be using the same parameters as my Matlab antenna design for a 2.45GHz patch antenna version 2 so I can compare the output results. If you are interested in the design process within Matlab I have linked my other posts in the Resources section. Each of the parameters is defined in the adjacent image.
We can then move to the next step by clicking the green “Go to Physics” button in the top right. This will bring up several tabbed menus to help you define the physical simulation parameters under which you will test your antenna at. The two most important are the simulation control and the dielectric.
The simulation control defines the frequency range over which the antenna is evaluated and the number of frequency steps are created. The dielectric determines the physical properties of the material that the microstrip antenna is mounted on.
In the case of my patch antenna design, I am simulating it from 2.3GHz to 2.7GHz with 10MHz frequency steps, and for the dielectric, I am using a modified FR4 material to match the Matlab parameters. FR4 is a common material used in the process of creating PCBs or printed circuit boards. I left the Air and Boundaries tabs as their defaults.
We can then click the green “Run” button at the top right hand of the interface to kick off the simulation. This will open the main GUI with a terminal output overlayed. This can be opened into a larger more readable size by expanding it.
Using the parameters I selected the simulation took about 30min total. After completion, the results will be displayed in ParaView. But the software will open to the main GUI so that you can go back and change things for a new run.
Results
The results of the simulation open in a viewing software called ParaView. It opens with several tabs that show the 3D radiation pattern at one frequency, the 2D radiation pattern lobes, and the S11 and VSWR of the antenna.
Comparing to Matlab
Comparing these results with my Matlab v2 patch design and physical measurements below it looks like the CENOS software are both generating the same radiation pattern. But the S11 is off by about 100MHz placing the antenna’s frequency at 2.55GHz not far off.
This could be due to a variety of reasons and I have trouble saying that I believe the Matlab 100% even though the results matched the real physical antenna. This does not invalidate the CENOS software at all as in reality true antenna design is an iterative process that can be confounded with many real-world interdependent variables. It took me more than a few tries to get my original design to where I wanted it.
Next Steps
This is an amazing piece of software that really opens the gates to more engineers and hobbyists getting into the design and manufacture of antennas at higher frequencies. with a more repeatable process that can be used as a step toward manufacturing.
I am not really sure why the design is approximately 100MHz away from the Matlab design and the resulting PCB. I would like to reconcile this discrepancy, I think it probably has to do with how the port parameters are being implemented so I might look at how to play with those. I also should upgrade to the latest version of CENOS to see if that corrects the problem as I am currently using 1.1.2 which is fairly out of date now and they have added a ton of features in the meantime.
I also want to create my own geometry using the CAD options. It is significantly different than how I have designed my other antennas in Matlab so that will take some practice. I also think it would be nice if I could import my current designs somehow.
Resources
I have included links to the CENOS antenna design documentation as well as an independent accuracy analysis of the CENOS software compared to HFSS and measured results.
CENOS Antenna Design Documentation
Independent Accuracy Analysis of CENOS
I have also included my version 2 design of my Matlab patch antenna design if you are interested in some more antenna content.
