[[File:PROP20(1).png|thumb|400px|EM.Terrano's Transmitter dialog with a user defined pattern selected.]]
A transmitter is a point radiator with a fully defined polarimetric radiation pattern defined over the entire 3D space in the standard spherical coordinate system. You can model a radiating structure using [[EM.Tempo|Cube]]'s other computational modules, [[EM.TEmpoTempo]], [[EM.Picasso]], [[EM.Libera]] or [[EM.Illumina]] , and generate a 3D radiation pattern data file for it. These The far-field radiation patter data are stored in a specially formatted file with a "'''.RAD'''" file extension. It file contains columns of spherical φ and θ angles as well as the real and imaginary parts of the complex-valued far -zoned electric field components '''E<sub>θ</sub>''' and '''E<sub>φ</sub>'''. The θ- and φ-components of the far-zone electric field determine the polarization of the transmitting radiator.
[[Image:Info_icon.png|40px]] Click here to learn more about the format of '''[[Data_Visualization_and_Processing#Far_Field_Data_Files | Radiation Pattern Files]]'''.
To define a transmitter source in EM.Terrano, first you need to have at least one '''Base Point''' base location point in your project workspace. Follow the procedure below:
* Right-click on the '''Transmitters''' item of the navigation tree and select '''Insert New Transmitter Set...''' from the contextual menu. This opens of the Transmitter Set dialog.
* You can also rotate the imported pattern about the three principal axes. Enter the rotation angles other than the zero default values, if necessary.
* Click the {{key|OK}} button of the dialog to close it.
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<td> [[Image:Terrano L1 Fig11.png|thumb|left|480px|The transmitter definition dialog.]] </td>
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[[File:Terrano L1 Fig13.png|thumb|left|480px|The property dialog of a transmitter set.]]
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A new transmitter set entry is added in the '''Transmitters''' section of the navigation tree. After defining a transmitter set, the base points associated with it change their color to the transmitter color, which is red by default. In the Transmitter Set dialog, you can also set the '''Baseband Power''' of your transmitter in Watts and its '''Phase''' in degrees. There is a check box labeled '''Custom Power''', which is checked by default. In that case, the power and phase boxes are enabled and you can change the default 1W power and 0° phase values as you wish. [[EM.Cube]]'s ".RAD" radiation pattern files usually contain the value of "Total Radiated Power" in their file header. This quantity is calculated based on the particular excitation mechanism that was used to generate the pattern file in the original [[EM.Cube]] module. When the "Custom Power" check box is unchecked, EM.Terrano will use the total radiated power value of the radiation file for SBR calculations.