G-N

G

Gain: The apparent increase in the strength of a signal radiated or received by an antenna caused by the antenna having better performance in some directions than others.

Gallon: Slang for the maximum transmitter power authorized for ham radio operators. 

Gateway: A node that is a part of more than one network and can be used to pass messages between those networks. 

General coverage: A term used to describe receivers and transmitters covering at least the frequency range of 500 kHz to 30 MHz and capable of operation in several different modes, including AM, CW, and SSB.

GHz: Abbreviation for gigahertz.

Gigahertz: Unit equal to 1000 megahertz or 1,000,000 kilohertz

GMT: Abbreviation for Greenwich mean time. 

Great circle route: The shortest path by radio between any two points on Earth.

Greenwich mean time: An international time and date system derived from the 0-degree meridian at Greenwich; this has since been replaced by coordinated universal time. 

Ground: A connection to a point of zero voltage, like the Earth.

Ground wave: A radio wave propagated along the surface of the Earth.

H

Hamfest: A large gathering of ham radio operators and other radio hobbyists.

Handle: A radio operator's name.

Harmonic: A frequency that is an integer multiple (two times, three times, etc.) of a lower frequency.

Hertz: One complete cycle of a radio wave per second.

Heterodyne: A high pitched "whistle" sound caused by two carriers interfering with each other. The pitch of the "whistle" depends on the frequency difference between the carriers.

HF: Abbreviation for high frequencies.

High frequencies: Frequencies from 3 to 30 MHz, although often used to refer to all frequencies from 1.7 to 30 MHz.

High pass filter: A filter that rejects all frequencies below a certain point, but which allows all higher frequencies to pass. 

Hollow state: A slang term for equipment that uses vacuum tubes. 

Homebrew: Slang term for home-built, noncommercial radio equipment.

Horizontal polarization: An antenna that radiates, or receives best, radio waves having their electric field parallel to the Earth's surface. 

Hyperscan: A very high scanning rate in a scanner receiver; also called turboscan.

Hz: Abbreviation for Hz.

I

ID: Abbreviation for "identification."

Impedance: The opposition to the flow of electric current and radio energy; it is measured in ohms. For best performance, the impedance of an antenna, the feedline, and the antenna connector on a radio should be approximately equal. 

Increment steps: The discrete frequency steps (10Hz, etc.) tuned by a receiver using frequency synthesis. 

Indirect FM: A term used to refer to phase modulation. 

Input frequency: The frequency on which a repeater station listens for signals to retransmit. 

Intermod: Short for "intermodulation," this means false or spurious signals produced by two or more signals mixing in a receiver or repeater station. 

International reply coupon: A coupon that can be purchased at post offices which can be exchanged in foreign countries for return postage for a surface mail letter to the country that issued the coupon. 

Ionosphere: The electrically charged region of the Earth's atmosphere located approximately 40 to 400 miles above the Earth's surface that refracts radio signals. 

Ionospheric storm: A disturbed condition in the ionosphere caused by release of charged particles by the sun which results in high absorption and poor radio propagation on most frequencies.

IRC: Abbreviation for International Reply Coupon.

J

Junkbox: Slang for the collection of spare parts and miscellaneous items kept by a radio operator or hobbyist.

K

Kerchunker: An operator that activates a repeater station by transmitting on its input frequency without speaking. 

kHz: Abbreviation for kilohertz. 

Kilohertz: Unit equal to 1000 hertz. 

Kilowatt: Unit equal to 1000 watts of transmitter power.

K-index: A measure of the Earth's magnetic field as measured at Boulder, Colorado. Propagation conditions improve with lower measurement numbers. 

kW: Abbreviation for kilowatt.

L

Landline: The telephone or a telephone call.

Lid: Slang for an incompetent, unskilled radio operator. 

Line of sight: Communication between two radio stations that are in visual sight (even if telescopically) with each other. 

Lockout: To remove certain channels from the scanning sequence of a scanner.

Longwave: Radio signals 300 kHz and lower in frequency, although this term is often used to mean any radio signal lower than 540 kHz. 

Loop antenna: A physically small receiving antenna usually designed for indoor use and tuning frequencies below 5 MHz; it receives in a figure 8 pattern. 

Lower sideband: The sideband lower in frequency than the transmitter's carrier.

Low pass filter: A filter that rejects all frequencies above a certain point, but which allows all lower frequencies to pass. 

LSB: Abbreviation for lower sideband. 

LUF: Abbreviation for lowest usable frequency, the lowest frequency that can support propagation between two points.

M

Machine: Slang for a repeater station.

Major lobe: The direction of maximum radiation or received signal strength for a directional antenna. 

Maritime station: A two-way radio unit aboard a ship or a station on land that communicates with ships. 

Mark frequency: In FSK, the higher of the two frequencies used. 

MCW: Abbreviation for modulated CW. 

Mechanical filter: A filter that uses a network of mechanical piezoelectric elements to obtain high rejection of unwanted signals. 

Medium wave: Radio signals from 300 to 3000 kHz, although this term is often used to mean any radio signal in the AM broadcast band (540 to 1700 kHz). 

Megahertz: Unit equal to 1,000,000 hertz or 1000 kilohertz. 

Megawatt: Unit equal to 1,000,000 watts of transmitter power. 

Meteor scatter: Propagation of signals on frequencies above 25 MHz via ionized trails left by meteors burning up in the ionosphere. 

MHz: Abbreviation for megaHertz (1,000,000 Hz). In older publications it may show as Mc for megacycle or 1,000, 000 cycles per second. 

Mobile station: A two-way radio unit installed in a car, boat, plane, etc., and used while in motion or at various stops.

Modulated CW: Sending Morse code over an AM transmitter using an audio tone. 

Modulation: The process of altering the output carrier of a transmitter in some way in order to convey information. 

Moonbounce: Slang term for EME communication. 

Monoband antenna: An antenna suitable for operation on just one band of frequencies. 

MUF: Abbreviation for maximum usable frequency, the highest frequency that can support propagation between two points. 

Multiband antenna: An antenna suitable for operation on several different bands of frequencies. 

Multihop: A radio signal refracted more than one time between the transmitting and receiving stations. 

MW: Abbreviation for megawatt.

N

Net: A group of stations that meet on a specified frequency at a certain time. The net is organized and directed by a net control station, who calls the net to order, recognizes stations entering and leaving the net, and authorizes stations to transmit. 

Noise blanker: A receiver circuit that reduces electrical noise by quieting the receiver during noise pulses. 

Notch filter: A circuit that takes a small "slice" out of the bandpass tuned by a receiver; this is useful for reducing interference from narrow bandwidth signals.