SIW ( substrate integrated waveguide)

I would be pretty greatful to one... if some one could tell me which simulator should i use to implement SIW concept with my slot antennas...?

Any simulator could simulate microstrip also could deal with SIW, e.g hfss, cst, ie3d...

For the SIW structure, full 3D EM simulator, like HFSS (FEM), CST (FDTD) should be used. The 2.5D simulator like IE3D, Momentum, Sonnet should not be used, since the the modelling will be more complicated and inefficient.