== Anatomy Of A Propagation Scene ==
An A typical propagation scene in [[EM.CubeTerrano]] propagation scene typically consists of several elements. At a minimum, you need a transmitter (Tx) at some location to launch rays into the scene and a receiver (Rx) at another location to receive and collect the incoming rays. A transmitter and a receiver together make the simplest propagation scene, representing a free-space line-of-sight (LOS) channel. A transmitter is one of [[EM.Cube]]'s several source types, while a receiver is one of [[EM.Cube]]'s several observable types. A simpler source type is a Hertzian dipole. A simpler observable is a field sensor that is used to compute the electric and magnetic fields on a specified plane.
An outdoor propagation scene may involve several buildings (modeled as impenetrable surfaces) and an underlying flat ground or irregular terrain surface. An indoor propagation scene may involve several walls (modeled as thin penetrable surfaces), a ceiling and a floor arranged according to a certain floor plan. You can also build mixed scenes involving both impenetrable and penetrable blocks, possibly along with irregular terrain surfaces. Your sources and observables can be placed anywhere in the scene. Your transmitters and receivers can be placed outdoors or indoors. A complete list of the various elements of a propagation scene is given in the '''Physical Structure''' section of [[Propagation Module]]'s Navigation Tree as follows:
* Impenetrable Surfaces
* Penetrable Surfaces
* Penetrable Volumes
* Terrain Surfaces
* Base Points
Impenetrable, penetrable and terrain surfaces and penetrable volumes all obstruct the propagation of electromagnetic waves (rays) in the free space. What differentiates them is the types of physical phenomena that are used to model their interaction with the impinging rays. Base points are simply used to define transmitter and receiver locations in the scene. The following sections of this manual will describe each of these elements in detail.
[[FileImage:PROP14(1).png]]Â Figure 1: |thumb|250px|The Navigation Tree of [[EM.Cube]]'s [[Propagation ModuleTerrano]].
=== The Various Types Of Surfaces & Blocks ===