Transmission paths: transmission paths also called transmission channel is the path between two nods of a network that a data communication follows. The term can refer to the physical cabling that connects the nodes on a network the signal that is communicated over the path way or a sub channel is a carrier frequency.
Ground waves: ground waves are radio wave which reaches a receiver from a transmitter directly with out reflection from the ionosphere.
Sky waves: a radio wave that is reflected back to earth by the ionosphere or a communications satellite; permits transmission around the curve of the earth's surface
Line of propagation: is the electro-magnetic radiation or acoustic wave propagation. Electromagnetic transmission light travels in a straight line. The rays or waves can be diffracted, refracted, reflected, or absorbed by atmosphere and obstructions with material and generally cannot travel over the horizon or behind obstacles. Ground waves: A surface of simultaneous and equal displacement of the particles composing a wave of vibration.
Space wave: The component of a ground wave that travels directly through space from a transmitting antenna to a receiving antenna; one part of the space wave goes directly from one antenna to the other; another part is reflected off the earth between the antennas.
Plane Polarised: a type of polarization in which the electric vector of waves of light or other electromagnetic radiation is restricted to vibration in a single plane.
AM: amplitude modulation is the encoding of a carrier wave by variation of its amplitude in accordance with an input signal.
FM: frequency modulation: The encoding of a carrier wave by variation of its frequency in accordance with an input signal.
VHF: very high frequency.
DAB: digital audio broadcasting: a system of broadcasting sound and written information using electronic signals that represent a series of the numbers 0 and 1.