Use the Matched Boundary Condition to make a boundary transparent for a wave (or waves) with the phase(s) as prescribed in the Wave Vectors settings of The Electromagnetic Waves, Beam Envelopes Interface settings.

Since the Wave Vectors settings are taken into account, this boundary condition is low-reflecting also for waves propagating with a large angle to the normal of the boundary, in contrast to the Scattering Boundary Condition, where the scattered beam should propagate almost in parallel to the boundary normal to be efficiently absorbed.

When Wave Vectors is set to bidirectional, select an Input wave—First wave (the default) or Second wave—that the specified input electric field is associated with.

Select an Incident field to specify whether the input wave is specified by the Electric field or the Magnetic field.

Specify the Incident electric field envelope E0 (SI unit: V/m) or Incident magnetic field envelope H0 (SI unit: A/m), depending on the Incident field selected. Notice that you only specify the envelope factor of the incident electric or magnetic field. The envelope function is internally multiplied by the phase function, as specified in the Wave Vectors settings, to form the complete incident electric or magnetic fields.

When Wave Vectors is set to bidirectional, if no scattered field is expected, select the No scattered field check box. This prevents COMSOL from returning spurious solutions that otherwise could appear between boundaries with unconstrained scattered fields.