hfss rcs plate

Hi All,
I'm using HFSS 11 to simulate a infinite flat metal plate. I've created a unit cell, defined master slave boundaries and floquet ports. I parametised the theta scan angle. The problem I'm having is that independent of the incident angle I get reflection coefficient magnitude of 1 for both TM and TE polarizations, which should only happen at normal incidence. Can anyone suggest what I'm doing wrong? I attach the project. Thanks

Did you define the metal by a Drude model? Normally metals are modeled in CST as perfect conductors.

I did not use the Drude model, I just defined a metal as normal in HFSS i.e a metal of finite conductivity. A look at the boundary solver view shows only the surface is highlighted as expected since there is no need for meshes inside the metal. I thought the drude model had to do with the conductivity of the metal rather than the scattering?
The interesting thing is if I put a dielectric in place of the metal, the reflection and transmision matches theory results obtained using fresnel equations.