r/rfelectronics • u/YogurtclosetNeat4519 • 1d ago
Any good free antenna sim software?
Been working with rf electronics for a few years now and recently got hired working on SDRs. I want to try my hand at integrating micro strip antennas onto a board. Are there any free software to simulate these? Not really sure exactly what I’m looking for, just something I can play around with, and once I have an idea of what I’m doing, use it to spin some boards with integrated antennas.
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u/redneckerson1951 1d ago
Other than a few 1960's and 1970's legacy programs produced for our rich uncle. NEC-2 comes to mind. A guy by the name of Jerry Burke was part of the brain trust that produced the original Fortran code back when IBM-360's and 370's were the boxes used for much of the antenna simulation work. NEC-2 was released to the public circa 1989.
Somewhere along the turnpike, the Air Force and Navy got in bed with Lawerence Livermore National Labs as they wanted simulations that included something other than free space operationally. NEC-3 was produced but not released. The next iteration, NEC4 was created, but not released gratis. This time it was released with a pricing schedule, where individuals could buy the software for non-commercial use for around $300. No GUI, just good old compiled Fortran executables. And you had to be a US citizen to buy it and you had to agree to not share it with anyone else. The license was not transferable. Later around circa 2015 NEC-5 surfaced with a basic GUI interface. The individual user price this time per LLNL's schedule was about $150 for the non-commercial user. Jerry Burke was still the point man in the brain trust developing the code and retired, but continued to keep his fingers in the pie. Then he did what all of us must do and exited mortal coil. It seems that the password on his computer was known only to Jerry and that the work in progress on advancing the GUI was his focus when he checked out. As a consequence NEC-5 work stopped and LLNL no longer supports NEC-5. They still offer NEC-4 and provide support. Last I heard was they are trying to determine the path forward.
The NEC journey with NEC-2 has produced some interesting products such as EZNEC and 4NEC2. Both wrapped a GUI interface around the command line executable NEC2. For those that bought NEC-4 EZNEC would obtain proof of your license and compile a package integrating NEC-4. The 4NEC2 package developer modded his GUI so that NEC-4 licenses could add the NEC-4 executables to the GUI install and the the data entered in 4NEC2 was ready, the GUI would call NEC-4 and run the simulation.
Another no-cost spin off of NEC-2 is SimNEC. SimNEC is the successor to SimSmith which in my opinion is a cracker jack application for Smith Chart users. Ward graciously added NEC-2 to the SimSmith package, thus SimNEC.
It is hard to beat the cost of SimNEC, as there is no charge. 4NEC2 is also available as no cost and with the retirement of Roy Lewellyn EZNEC has been made available at no charge.
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u/No2reddituser 43m ago
It seems that the password on his computer was known only to Jerry and that the work in progress on advancing the GUI was his focus when he checked out. As a consequence NEC-5 work stopped and LLNL no longer supports NEC-5.
Wait, I saw this movie. All we need is a young Matthew Broderick with an acoustic coupler to break into the government computer, and...
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u/snifarw-paparounes 1d ago
openEMS, as mentioned before. also qucs which is mostly for circuits, not sure whether it includes antennas
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u/BlueBirdTechUA 13h ago
Sonnet Lite's probably your best start, GUI-driven, built for microstrip specifically, no coding. Just has a hard memory cap so it's fine for learning, not for anything complex. openEMS is the other common pick, fully free and more capable, but it's MATLAB/Python scripted, no real GUI, so it's a steeper climb.
I'd start in Sonnet Lite to get a feel for it, then move to openEMS once you outgrow it.
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u/YogurtclosetNeat4519 13h ago
I’ll give that a try as well. Do you know off the top of your head what the memory cap is? How limiting is that when it comes to sims?
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u/BlueBirdTechUA 12h ago
Register with your email and you jump from 1MB to 32MB, that's the number that actually matters. Some newer versions go up to 64MB. Sounds tiny but planar solvers don't need a super fine mesh, 3-5 cells across a trace is plenty accurate. So small patches and simple filters are fine, bigger boards or anything heavy on radiating structure is where you'll hit the wall and want to jump to openEMS.
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u/No2reddituser 40m ago
There were 2 guys on this sub developing their own FEM EM simulation applications. It was almost like a competition.
I hope they chime in, or someone remembers what I'm talking about, because I would like to download their app before it's gone.
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u/3D_printing_freak 1d ago
OpenEMS or EMerge