simualtion of inductive coupling between two flat PCB coils

Hello,
I would like to compute (simulate) the variation of the inductive coupling (or the mutual inductance) between two flat coils printed on a PCB versus the distance. The two coils have a 2.5μH value and the operating frequency is about 13MHz. Do you know if there is any software which may help me? I heard about sonnet, maxwell but it's quite confusing with me....
Could you help me?
Thanks a lot,
Dargo

Sonnet lite which is a free download should be able to handle this.

as you have planar structure you should use the MoM based software. Sonnet and Momentum / ADS are proved to be best environments. Anyway I recently saw some 13.56MHz RFID projects running under CST as well.

rinox

Hello!
Thanks for your answers. A soon as my version of Sonnet Lite will be registred I will
try to compute the mutual inductance between my 2 coils. By the way, is it regular to wait for 2 weeks to have a registration with sonnet Lite?
I keep you post

Dargo

My sonnet lite registration came back within a few minutes. You might want to try again.

-Joe