</table>
== Defining Point Transmitters & Receivers for Your Propagation Scene ==
=== The Nature of Transmitters & Receivers ===
In EM.Terrano, transmitters and receivers are indeed point radiators used for transmitting and receiving signals at different locations of the propagation scene. From a geometric point of view, both transmitters and receivers are represented by point objects or point arrays. These are grouped as base locations in the "Physical Structure" section of the navigation tree. As radiators, transmitters and receivers are defined by a radiator type with a certain far-field radiation pattern. Consistent with [[EM.Cube]]'s other computational modules, transmitters are categorizes as an excitation source, while receivers are categorized as a project observable. In other words, a transmitter is used to generate electromagnetic waves that propagate in the physical scene. A receiver, on the other hand, is used to compute the received fields and received signal power or signal-to-noise ratio (SNR). For this reason, transmitters are defined and listed under the "Sources" sections of the navigation tree, while receivers are defined and listed under the "Observables" section.
EM.Terrano provides three radiator types for point transmitter sets:
#Half-wave dipole oriented along of the the principal axes
#User defined (arbitrary) antenna with imported far-field radiation pattern
EM.Terrano also provides three radiator types for point receiver sets:
#Half-wave dipole oriented along of the the principal axes
*Using the "Basic Link" wizard
=== Defining a Point Transmitter Set in the Formal Way ===
Transmitters act as sources in a propagation scene. A transmitter is a point radiator with a fully polarimetric radiation pattern defined over the entire 3D space in the standard spherical coordinate system. By default, [[EM.Terrano]] assumes that your transmitter is a vertically polarized half-wave resonant dipole antenna. This antenna has an almost omni-directional radiation pattern in all azimuth directions. It also has radiation nulls along the axis of the dipole. You can override the default radiator option and select any other kind of antenna with a more complicated radiation pattern. For this purpose, you have to import a radiation pattern data file to [[EM.Terrano]]. You can model any radiating structure using [[EM.Cube]]'s other computational modules, [[EM.Tempo]], [[EM.Picasso]], [[EM.Libera]] or [[EM.Illumina]], and generate a 3D radiation pattern data file for it. The far-field radiation patter data are stored in a specially formatted file with a "'''.RAD'''" file extension. This 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.