From high school physics we know that light refracts passing from one medium to another. The incident and refracted angles can be found using famous Snell–Descartes law.  According to Snell–Descartes law, there would be an angle, known as critical angle, in which the refracted light can no longer enter the second medium. It is called total internal reflection.

 [Source of picture: Wikipedia: Behavior of a ray incident from a medium of higher refractive index n1 to a medium of lower refractive index n2 ,  at increasing angles of incidence]

If incidence angle < critical angle, the wave enters in the second medium. This has been shown by visualizing the electric field.

We see that in case of total internal reflection no field could enter in second medium and the energy will all be kept inside the first medium.

Electric field 

                                                                       Power Flow

How is it implemented in CST Studio Suite?

Unitcell Boundary Condition (available in Frequency solver) enables the user with two dimensional infinite array in x and y directions in combination with Floquet ports in Zmin and Zmax directions. The desired incidence angle of the Flouqet modes can be set by user. The first two modes are the fundamental plane waves created in the direction of incidence angles.

Images below show a short summary of this procedure.

Should you have any questions, please feel free to contact me or the Simulia CST Studio Suite support team. 

⭐Want to discover some more detail about features in the CST Studio Suite ​​​​​​​R2021x ​​​​​​​release? Check out these demos from our experts:

 

⭐Find out more about CST Studio Suite on our Learning Resources wiki page

 

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