# '''[[FDTD_Source_Types#Plane_Wave_Source|Plane Wave Source]]''': A distributed source with a plane wave profile defined using a virtual box object enclosing the entire physical structure.
# '''[[FDTD_Source_Types#Gaussian_Beam_Source|Gaussian Beam Source]]''': A distributed source with a complex-valued focused Gaussian beam profile defined using a virtual box object enclosing the entire physical structure.
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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.
{{Note|In order to create a lumped source, you must have at least one line object or line array in the project workspace.}}
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{{Note|In order to define a waveguide source, you must have at least one hollow box object with no caps or only one end cap or a hollow box array in your project.}}
[[Image:Info_icon.png|40px]] Click here to learn more about the various '''[[FDTD Source Types]]'''.