Waveguide structures have many applications at microwave and millimeter wave frequencies. For example, a rectangular waveguide is used to feed a pyramidal horn antenna. A waveguide structure is usually excited using some type of strategically located probe mechanism. This can be modeled using a lumped source placed on a wire structure made up of line objects. Alternatively, use can use EM.Cube's '''Waveguide Sources''', a special type of source that excites a prescribed modal field distribution in a rectangular waveguide structure. The scattering parameters are calculated from knowledge of incident and reflected fields at designated waveguide ports. Waveguide sources typically provide more accurate results for scattering parameters compared to lumped ports as they represent the actual dominant propagating modes at the transmission line ports.
EM.Cube provides special waveguide sources that can excite either the TE<sub>mn</sub> or TM<sub>mn</sub> modes of a rectangular waveguide which is oriented along one of the three principal axes. In other words, the plane of the waveguide source must be parallel to one of the principal (XY, YZ or ZX) coordinate planes. <font color="red"><u>'''Â {{Note|In order to create a waveguide source, you must have at least one "Hollow" Box object with no caps or only one end cap in your project.'''</u></font> }}Â To create a new waveguide source, follow these steps:
* Right click on the '''Waveguide Sources''' item in the '''Sources''' section of the Navigation Tree and select '''Insert New Source...''' to open the Waveguide Source Dialog.