In order to perform an electromagnetic simulation in any of [[EM.Cube]]'s computational modules, you need to excite your physical structure using some kind of source. In most cases, you can define more than one source if necessary. In [[EM.Tempo]], a source pumps energy into your FDTD computational domain in the form of a temporal waveform varying as a function time. In the MoM-based modules, [[EM.Picasso|EM.picasso]] and [[EM.Libera]], a source provides the "right-hand-side (RHS)" vector of the MoM linear system resulting from the integral equation formulation of your boundary value problem. In EM.Illuumina, a source is used to illuminate your surfaces. In [[EM.Terrano]], a source acts as a transmitter that launches the broadcast signal into the free space. In [[EM.Ferma]], you need either an electric or magnetic source to set the boundary conditions for the Laplace equation or provide the source term for the Poisson equation.
In each module, you should choose the right source type depending on the purpose of your simulation and based on the observables you define for your project. For example, for computing the radar cross section (RCS) of a target, you need a plane wave source. If you are interested in computing the S/Z/Y [[parameters]] of your structure, then you have to choose a source type like a gap or lumped source that supports a "Port Definition" observable.
<table>