FDTD Boundary Conditions

= Usage =

function FDTD = SetBoundaryCond(FDTD, BC, varargin)

BC = [xmin xmax ymin ymax zmin zmax];

= Types of Boundary Conditions (BC)=
 * PEC: Perfect electric conductor (default BC)
 * PMC: Perfect magnetic conductor
 * MUR: A simple absorbing boundary condition (ABC)
 * PML_x: Perfectly Matched Layer absorbing boundary condition, using x number of cells

Perfect electric conductor (PEC)

 * All tangential electric fields on this boundary will be set to zero. This results in the behavior as a perfect electric conductor. This BC is the default in a FDTD simulation.

For example, this BC can be used to model waveguide walls or a infinite ground-plane for PCB board.

Perfect magnetic conductor (PMC)

 * All tangential magnetic fields on this boundary will be set to zero.
 * This results in the behavior as a perfect magnetic conductor. Since there is no real material with such a behavior, it is usually used as symmetry boundary condition.
 * Since in FDTD all magnetic fields are shifted by half a cell, this wall is effectively located in the middle of the last two lines of the respective direction.

MUR ABC

 * Simple absorbing boundary condition (ABC)
 * Only works perfect for a completely orthogonal impinging waves with a known phase-velocity (e.g. speed of light)

PML_x ABC

 * Artificial x-cells thick layer that effectively absorbs incoming EM waves. (default x=8)
 * PML thickness can be 6 to 20 cells. PML_8 is a good default.
 * Warning: In openEMS the last x lines in the respective direction are defined as this artificial absorbing material: Keep your structures far enough away!
 * Info: This ABC is not optimally implemented regarding the simulation speed. Use the Mur-ABC for faster simulations.