Comsol has a built-in impedace boundary condition, which is an implementation of Leontovich boundary conditions in a form:
Z_s (n x H) = E_t,
Where Z_s is the surface impendance, H is the magnetic field and E_t is the electric field projected on the boundary.
This all makes sense.
What does not make sense for me is the weak formulation of the problem.
Among other auxilullary things, the surface current density is calculated: Js = (emw.tEx+emw.Esx)/emw.Zc
And the weak equation is written as (I skip the normalization constant):
(-emw.imp1.Jsx*emw.testPhystEx-emw.imp1.Jsy*emw.testPhystEy-emw.imp1.Jsz*emw.testPhystEz)
So, what is testPhystE*? I cannot find this in the manual. I've read about the test function, but they use a form of test(u). Is this the same thing?
If it is, what is written is a surface integral of J.Et = 0. How is this related to the original equation Z_s* nxH = Et?