Simulating search coils with FEMM 4.2

[joop]

We all are familiar with using spice software for simulating electronics, but how about simulating the magnetic fields generated by search coils with the help of free software? The reason I want to simulate is to get a better understanding of the different coil shapes, but also how a coil will behave with different types of soil.

I came across femm 4.2 and spent a couple of hours getting familiar with the software. To start I have simulated a simple coil with 100 windings of 0.8 mm wire in air. The diameter is 30 cm. It is driven with 1 Amp at 10 kHz. What you see in the picture is the field strength in ampere per meter, flux lines and field direction (the little arrows).

Attached is the simulation fille. Save it to your disk, rename to 30cmcoil.FEM and load it into femm. Select Mesh->Create Mesh from the menu. Next select Analysis->Analyze and Analysis->View Result. Click on the coloured button next to the arrow button for a contour plot.

I am not sure if I am on the right track (AZIZ, please help me out ).

[Aziz]

There you have it. A complete open-source and well documented stuff.

But I can't help you. I have to learn it as well. But I do not need to use the stuff from others.

Cheers,
Aziz

[joop]

Well, I can at least compare with your pictures on the forum. That should give me an idea if my simulations are correct.

[Davor]

I admire your persistence. It was a tad too much of everything to me. I am very friendly with spice and NEC, but this was a bit too much.

Maybe now that you chipped some ice ...

[joop]

Thanks Davor,

I have planned to come up with some more examples in the weeks to come, once I have figured out how to get soil properties into the model. I will also try and do some coil comparisons.

Regards,
Joop

[bernte_one]

hello joop

if i follow your steps there comes an error message at the point when i choose
show results - can find 30cmcoil.fem.ans?

did you have this ans, can you upload it?

regards

[joop]

Hi Bernt.

the .ans file is the result of the simulation. I think you incorrectly renamed my file. Be sure to name it 30cmcoil.FEM, not 30cmcoil.fem.

[pagantroll]

Dear Joop,
I came to the same point :-) did you finally succeeded with your simulations? Would be very interessting. There is not to much to find outside.

I am currently experimenting (moving an object towards the coil by a lua script and checking the change of inductance) but seams that I either do not have the right simulation precission (i.e. meshgrid) or my assumed coil is just to incensitive.... :-)

BR,
Pagan