To excite a metal trace with a wave port, apply the wave port attribute to the end of the trace. Any symmetry planes in your geometry must bisect the port. RF3p extracts the port plane at the beginning of the port solve, creating a port mesh that includes all structures and materials in the plane that are electrically linked to the trace end. The next step is to perform an eigenanalysis on the port mesh, determining the mode excitations corresponding to excitation of the port in the environment of the port plane. The resulting modes are used to insert energy into the volumetric system during the full solve.
RF3p computes as many modes as there are conductors on the wave port plane, regardless of how many of those conductors are ports. The modes are sorted by wave number, and the first mode (or combination of degenerate modes) that satisfies the voltage constraints is returned. In addition, RF3p attempts to select a mode that will bring all non-port conductors in the port plane to a common ground. If none of the modes satisfy the voltage constraints, the solver returns an error and terminates. In this case, change the solver parameters (using a finer mesh, larger number of eigensolver iterations, etc.) if you believe there should be a solution. If the geometry is truly too complex, you may wish to simplify your geometry, or break the port into regions that can be simulated independently using custom extents (described in Custom extents).
The following image shows the port mesh for a system with wave ports assigned to three traces, with the ports indicated in red. A fourth metal slab is adjacent to the port plane, and this slab is indicated as PEC. This image shows proper use of a differential port.
In this geometry, port 1 is assigned to the end of a thick metal trace, and port -1 is assigned to the ends of two zero-thickness metal traces. Both applications are valid. Wave ports may be assigned to conducting faces and conducting edges, and you may use either type of application alone or in combination, as is done here.
The PEC slab separates the bottom portion of the port plane from the rest. Even though those regions are not electromagnetically isolated in the full geometry, they are isolated within the 2D port plane. Consequently the port mesh does not include the bottom portion of the plane. In the volumetric solve, these independent regions of the port plane are given PMC boundary conditions.