Antenna terms, and definitions

Earth Station: The ground-based portion of a satellite communications system is called an earth station or a ground station. The station consists of an antenna and receiver (or transceiver) that are in communication with a satellite in geosynchronous orbit.

Efficiency: The ratio of power output to power input.

Effective height: 1. The height of the center of radiation of an antenna above the effective ground level. 2. In low-frequency applications involving loaded or nonloaded vertical antennas, the moment of the current distribution in the vertical section divided by the input current. Note: For an antenna with symmetrical current distribution, the center of radiation is the center of distribution. For an antenna with asymmetrical current distribution, the center of radiation is the center of current moments when viewed from points near the direction of maximum radiation.

Effective monopole radiated power (e.m.r.p.): The product of the power supplied to the antenna and its gain relative to a short vertical antenna in a given direction.

Electromagnetic field: The field of force that an electrical current produces around the conductor through which it flows.

Electromagnetic waves: A wave propagating as a periodic disturbance of the electric and magnetic fields and having a frequency in the electromagnetic spectrum; the means by which energy is transmitted from one place to another.

Electrostatic discharge (ESD): The rapid, spontaneous transfer of electrostatic charge induced by a high electrostatic field. Usually the charge flows through a spark (static discharge) between two bodies at different electrostatic potentials as they approach one another.
More information; electrostatic discharge page.

Element: A part of an antenna that can be either an active radiator or a parasitic radiator.

End-fed: An antenna whose power is applied to one end rather than at some point between the ends.

Antenna "F" Terms and definitions