In a 3D SBR simulation, a transmitter shoots a large number of rays in all directions. The electric fields of these rays are polarimetric and their strength and polarization are determined by the designated radiation pattern of the transmit antenna. The rays travel in the propagation scene and bounce from the ground and buildings or other scatterers or get diffracted at the building edges until they reach the location of the receivers. Each individual ray has its own vectorial electric field and power. The electric fields of the received rays are then superposed coherently and polarimetrically to compute the total field at the receiver locations. The designated radiation pattern of the receivers is then used to compute the total received power by each individual receiver.
From a theoretical point of view, the radiation patterns of the transmit and receive antennas are independent of the propagation channel characteristics. For the given locations of the point transmitters and receivers, one can assume ideal isotropic radiators at these points and compute the polarimetric transfer function matrix of the propagation channel. This matrix relates the received electric field at each receiver location to the transmitted electric field at each transmitter location. In general, the vectorial electric field of each individual ray is expressed in the standard local standard spherical coordinate system at the transmitter and receiver locations. In other words, the polarimetric channel matrix expresses the '''E<sub>θ</sub>''' and '''E<sub>φ</sub>''' field components associated with each ray at the receiver location to its '''E<sub>θ</sub>''' and '''E<sub>φ</sub>''' field components at the transmitter location. Each ray has a delay and θ and φ angles of departure at the transmitter location and θ and φ angles of departure at the receiver location.
=== Changing the SBR Engine Settings ===