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I would like to perform electromagnetic simulation and analysis of simple PCBs (coupling, capacitance, impedance, EMI, etc.)

Are there any reasonably priced (sub £1000), or free packages available which will do this?

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closed as off-topic by Fizz, PeterJ, Null, JRE, Ricardo Oct 22 '15 at 11:00

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    \$\begingroup\$ No, there are not any tools which are reasonably priced, much to my chagrin. Feko was suggested to me by my friend whom does EMC research for his graduate studies, he has had great results, but told me that it is still not easy to do. It takes him quite a bit of time to get even basic split ground plane simulations done. One of my good friends at NI uses some pretty fantastic software for simulating these things but they as a company, a decently large one, determined the cost of having more than one seat of a license not feasible. \$\endgroup\$ – Kortuk Apr 14 '12 at 19:19
  • \$\begingroup\$ Aw, this is sad. I mean, how hard can it be? \$\endgroup\$ – Rocketmagnet Apr 14 '12 at 19:21
  • \$\begingroup\$ yes, I have great interest in the area also. I have wanted to spend more time on it but have not had time recently. If I ever reach decent results with Feko I will shoot you a ping. There is software that will do some pretty advanced Design Rule Checks to help reduce issues with EMI. \$\endgroup\$ – Kortuk Apr 14 '12 at 19:22
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    \$\begingroup\$ The reason it costs so much is because of the unbelievable amount of work that goes into an FEM or MoM solver for a PCB \$\endgroup\$ – Kortuk Apr 14 '12 at 19:31
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    \$\begingroup\$ Well, that, and the tiny market. But is it any more work than any other CAD package ? \$\endgroup\$ – Rocketmagnet Apr 14 '12 at 19:39
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crunchyard.com offers cloud-based renting of CPU time which includes, as an option, Feko. You pay for VM/hour and the prices are quite reasonable.

You can download a free trial of Feko at their website which is unrestricted for 45 days (requires a login registration). There's also a free Lite version that you can use without time restrictions (you just need to ask for a license) but it has stringent limitations to simulation complexity. One thing you could do is use the Lite version to create/edit your model and then rent time at Crunchyard to run the simulation.

The Trial and Lite versions include good instructional videos for the basics of using Feko. But, as Kortuk said, it's laborious to recreate the PCB in it. One alternative you have is to import other CAD formats like DXF, provided your PCB design software supports it. But you're obviously importing just the geometry, not the EM profile of the traces. Those AFAIK you'll have to setup by hand. By reading Feko manual it appears that when importing Parasolid files it'll recognize special attributes of the objects that may contain EM characteristics, but I never tried it. You'd need a PCB software that can export that format and also be able to read those characteristics from somewhere (the schematics perhaps).

This is the simulation result for a simple PCB rectangular surface area.

enter image description here

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  • \$\begingroup\$ Can you give us more info here about the product so that the link is not all we have. \$\endgroup\$ – Kortuk May 21 '12 at 6:19
  • \$\begingroup\$ Sorry @Kortuk, I was in a rush that day and never revisited it later. Hope it's better now. \$\endgroup\$ – fceconel May 22 '12 at 17:16
  • \$\begingroup\$ much better but I always ask for more. Any screenshots? \$\endgroup\$ – Kortuk May 23 '12 at 14:45
  • \$\begingroup\$ Check it out... \$\endgroup\$ – fceconel May 23 '12 at 22:45
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If you Google "microstrip coupling calculator" and "microstrip impedance calculator" you may find a couple of tools for the passive calcs.

EMI is another matter. To determine the far field strength at 300 MHz from your board, what 300 MHz drive voltages and currents would you use in the simulation to represent to output from the 30 MHz processor on the board? Or whatever frequencies and harmonics are applicable for your board?

Because it is so difficult to come up with believable values for driving voltages and currents, often one uses: an existing body of design knowledge, best design practices, design iteration, and testing. This may be why folks are reluctant to develop a software simulator.

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  • \$\begingroup\$ I can see that for serious applications, like developing consumer products etc, where you really need reliable quantitative results, this would be difficult. I would be happy with some simple simulations that would give me results good enough for qualitative learning. \$\endgroup\$ – Rocketmagnet Apr 14 '12 at 22:33
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There is an emerging open-source candidate as well, which works in conjunction with Matlab or Octave.

http://openems.de/start/index.php

This can import a Hyperlinx data file, such as can be exported from Eagle and many other PCB layout tools. I've inquired about support from KiCad, but at the time they did not yet output Hyperlynx format. It's been several months, so may be time to check on that again.

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  • \$\begingroup\$ Of the free stuff there's also petr-lorenz.com/emgine but focuses on antennas. I don't think it can import hyperlynx. \$\endgroup\$ – Fizz Oct 22 '15 at 2:18
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Sonnet Lite is a free but stripped-down version of their profi tools; for a comparison see this. The main limitations of the free Lite version are:

  • max two metalization levels
  • maximum of three dielectric layers available
  • maximum of 4 ports
  • only one parameter in a parameter sweep
  • 32 Megabyte memory limit (if you register, otherwise just 1MB)

Can still do PCB trace crosstalk analysis, in theory, though. It does not expire (unlike the one in the accepted answer). Alas the aforementioned limitations are pretty crippling. You can't run basically any of their included examples. For a 0402 resistor model you get this:

enter image description here

And even for simpler stuff the memory limitation is pretty crippling, e.g. the following wideband filter can't be simulated in Lite because of that:

enter image description here

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