Scattering boundary condition and port with plane wave

Dear all,

I want to simulate the periodic nanostuctures on silicon. now i am using comsol 4.3a version which is not supported PML with port boundary. for that i need to define the Scattering boundary condition at the port and also how to calculate the Reflection and transmittance for port.

some body help me how to implement both scattering boundary condition at the port.

Thanks