CST2013: Boundary Conditions - Phase Shift/Scan Angles

Simulation: Settings Boundaries   Phase Shift/Scan Angles

This property page allows you to define values for phase shifts or scan angles for unit cell or periodic boundary conditions.

Note: These settings are supported by the frequency domain solver and the eigenmode solver. For the transient solver, the values for phase shifts / scan angles must be zero.

If a frequency domain solver calculation is performed and waveguide ports share one or two pairs of edges with periodic boundaries, the phase shift and constant angle of incidence definitions affect the port modes. For instance, if a constant angle of incidence is specified, homogeneous ports with periodic boundaries yield a plane wave propagating along the direction given in spherical coordinates (theta and phi, see below), and a number of higher-order Floquet modes.

X/Y/Z

Set the phase shift in degrees for the X, Y or Z direction here. Each field is only editable if a periodic boundary condition is used for the plane perpendicular to X, Y or Z, respectively.
The fields on the upper periodic boundary condition are then equal to the fields on the lower periodic boundary condition times the phase factor, for instance
E( x_min + d x) = exp( i d f_x ) E( x_min ),
where d x > 0 is the spatial lattice period in X direction, and d f_x is the phase shift in X direction.

Scan Angles

This option only applies to the frequency domain solver.

If activated, you may enter an angle modifying the phase on the periodic boundaries. The periodic phase shift is changed across the periodic boundaries according to the phase value of an imaginary incident plane wave at the boundaries with the angles theta and phi.

Please note that the angles theta and phi refer to the spherical coordinate system with the z-axis as polar axis. Therefore, you currently may not enter a constant angle if the periodic boundaries are located at the zmin/zmax position.

If constant angles are activated, the spherical coordinate system with the angles theta and phi is displayed in addition to the structure and boundaries.

Theta

Enter the value for theta in degrees here. Theta is the angle between the z-axis and the propagation direction of a plane wave in background material. This option only applies to the frequency domain solver.

Phi

Enter the value for phi here. Please note that if the periodic boundaries are located only at the xmin/xmax position phi is set to 0 degrees automatically. If the periodic boundaries are located only at the ymin/ymax position phi is automatically set to 90 degrees. This option only applies to the frequency domain solver.

Outward/Inward

Whether the scan angle Theta, Phi specifies the direction of an outgoing or incoming plane wave can be specified here. If the plane wave propagation vector has a positive z-component, then the Floquet port at the lower z-boundary has two fundamental modes which correspond to the outward traveling plane wave in the given direction. The corresponding port modes at the upper Floquet port boundary however do not represent the plane wave which is incoming from the same direction. To excite this plane wave at the upper Floquet port, change the direction to inward.

OK

Accepts your settings and leaves the dialog box.

Cancel

Closes this dialog box without performing any further action.

Help

Shows this help text.

See also

Frequency Domain Solver

Boundary Conditions: Boundaries, Symmetry Planes, Unit Cell, Boundary Temperature