A lumped source is the most commonly used way of exciting a structure in [[EM.Tempo]]. A lumped source is an ideal source that must be placed on a line object that is parallel to one of the three principal axes and shows up as a small red arrow on the host line. Lumped sources are typically used to define ports and compute the port characteristics like S/Y/Z [[parameters]].
Waveguide source is used to excite the dominant TE<sub>10</sub> mode of a hollow rectangular waveguide. Waveguide sources typically provide more accurate results for scattering [[parameters]] of waveguide structures compared to lumped sources as they represent the actual dominant propagating modes at the transmission line ports.A plane wave source is another popular excitation method that is used for calculation of the radar cross section of targets or reflection and transmission characteristics of periodic surfaces.
{{Note|In order to create a lumped source, you must have at least one line object or line array in the project workspace.}}