| A - B | C - D | E - F | G - H | I - J | K - L | M - N | O - P | Q - R | S - T | U - V | W - X | Y - Z |

E region
The second lowest ionospheric region, the E region exists only during the day. Under certain conditions, it may refract radio waves enough to return them to Earth.

Earth ground
A circuit connection to a ground rod driven into the Earth or to a cold-water pipe made of copper that goes into the ground.

Earth station
An amateur station located on, or within 50 km of, the Earth's surface intended for communications with space stations or with other Earth stations by means of one or more other objects in space.

Earth-Moon-Earth (EME) or Moonbounce
A method of communicating with other stations by reflecting radio signals off the Moon's surface.

Electric field
An invisible force of nature. An electric field exists in a region of space if an electrically charged object placed in the region is subjected to an electrical force.

Electromotive force (EMF)
The force or pressure that pushes a current through a circuit.

Electron
A tiny, negatively charged particle, normally found in an area surrounding the nucleus of an atom. Moving electrons make up an electrical current.

Elmer
An individual who acts as an advisor or mentor to a newly licensed amateur.

Emergency
A situation where there is a danger to lives or property.

Emergency traffic
Messages with life and death urgency or requests for medical help and supplies that leave an area shortly after an emergency.

Emission
The transmitted signal from an amateur station.

Emission privilege
Permission to use a particular emission type (such as Morse code or voice).

Emission types
Term for the different modes authorized for use on the Amateur Radio bands. Examples are CW, SSB, RTTY and FM. Energy - The ability to do work; the ability to exert a force to move some object.

F region
A combination of the two highest ionospheric regions, the F1 and F2 regions. The F region refracts radio waves and returns them to Earth. Its height varies greatly depending on the time of day, season of the year and amount of sunspot activity.

False or deceptive signals
Transmissions that are intended to mislead or confuse those who may receive the transmissions. For example, distress calls transmitted when there is no actual emergency are false or deceptive signals.

Feed line
The wires or cable used to connect a transmitter, receiver or transceiver to an antenna. See Transmission line.

Filter
A circuit that will allow some signals to pass through it but will greatly reduce the strength of others. Final 1) The final tube(s) or transistors in an amplifier - - "I just put new finals in this transmitter and I'm getting a lot more power output." 2) The last transmission in a contact before singing off - - "OK this will be my final for now, see you again next time".

Frequency
The number of complete cycles of an alternating current that occur per second.

Frequency bands
A group of frequencies where amateur communications are authorized.

Frequency coordination
Allocating repeater input and output frequencies to minimize interference between repeaters and to other users of the band.

Frequency coordinator
An individual or group that recommends repeater frequencies to reduce or eliminate interference between repeaters operating on or near the same frequency in the same geographical area.

Frequency discriminator
A type of detector used in some FM receivers.

Frequency modulated (FM) phone
The type of signals used to communicate by voice (phone) over most repeaters. FM is a method of combining an RF carrier with an information signal, such as voice. The voice information (or data) changes the RF carrier frequency in the modulation process. (see Amplitude modulation). As you might suspect, we use voice or data to vary the frequency of the transmitted signal. FM broadcast stations and most professional communications (police, fire, taxi) use FM. VHF/UHF FM voice is the most popular amateur mode.

Frequency privilege
Permission to use a particular group of frequencies.

Front-end overload
Interference to a receiver caused by a strong signal that overpowers the receiver RF amplifier ("front end"). See also receiver overload.

Fuse
A thin metal strip mounted in a holder. When too much current passes through the fuse, the metal strip melts and opens the circuit.