What is the best way to create coils (rectangular) ? -a large rectangular coil with N turns, with a smaller rectangular coil with N turns inside (centred in the middle of the larger rectangular coil).

Also I need to simulate -what is best simulator to use to look at magnetic field/ coupling, etc ? The frequency of operation is about 10MHz.

Any existing example would be appreciated.

CST Studio Suite ​​​​​​​