The Plane Wave Radiation node adds a radiation boundary condition for a plane wave. If required add an Incident Pressure Field to model an incoming wave. This radiation condition allows an outgoing plane wave to leave the modeling domain with minimal reflections, when the angle of incidence is near normal. Add this node from the Radiation Conditions submenu.

The plane wave type is suitable for both far-field boundaries and ports. Because many waveguide structures are only interesting in the plane-wave region, it is particularly relevant for ports. When using the radiation condition on an open far-field boundary, it is recommended to construct the boundary such that the incidence angle is near to normal, this of course requires a priori knowledge of the problem and the solution. See the theory section Theory for the Plane, Spherical, and Cylindrical Radiation Boundary Conditions for details about the equations and the formulation of this nonreflecting boundary condition.