Ham Radio Glossary

Plain-English definitions of common amateur-radio terms you'll run into as a newcomer.

146.520: The national 2-meter FM simplex calling frequency. A good place to call and listen when you're mobile or testing simplex.
73: Ham shorthand for "best regards." Operators sign off a contact with "73" (never "73s").
Ampere: The unit of electrical flow (current), often shortened to 'amp'.
Amplitude: How big or 'tall' a wave is, which is basically how strong it is.
Antenna: The metal piece that turns your radio's electricity into radio waves and back again. A good antenna often matters more than radio power.
APRS: Automatic Packet Reporting System, a digital mode used to share GPS location, weather, and short messages.
ARES: Amateur Radio Emergency Service, ARRL-sponsored volunteers who provide communications during emergencies.
ARRL: The American Radio Relay League, the national association for amateur radio in the United States.
Band: A range of frequencies set aside for a purpose, referred to by wavelength (e.g., the "2-meter band" or "20-meter band").
Bandwidth: How much room on the dial a signal takes up — wider signals use more space.
Call sign: Your unique FCC-issued station identifier (for example, W9XYZ). You must use it to identify on the air.
Calling frequency: A frequency agreed upon for making initial contact; after answering, stations usually move ("QSY") to another frequency to chat.
Capacitor: A part that stores electricity for a short time, like a tiny rechargeable bucket.
Carrier: The plain, steady radio wave that your voice or data rides on.
Coax: The common round cable (coaxial cable) used to connect a radio to its antenna.
Conductor: A material like copper that lets electricity flow through it easily.
Control operator: The licensed person responsible for what a station transmits.
Current: The flow of electricity through a wire, measured in amperes (amps).
CW: Continuous Wave, the technical name for Morse code sent by switching a carrier on and off.
D-STAR: An Icom-originated digital voice and data mode with internet linking for long-distance contacts.
Decibel: A way of comparing signal or power levels; every 3 decibels is about double the power.
Diode: A part that lets electricity flow only one way, like a one-way gate.
Dipole: A simple antenna made of two equal wires fed in the middle.
DMR: Digital Mobile Radio, a digital voice mode that uses "talkgroups" and often links worldwide over the internet.
Duplex: Transmitting and receiving on two different frequencies at once, as repeaters do.
Duty cycle: The fraction of time you're actually transmitting versus resting; higher duty cycle means more RF energy.
DX: A distant station, often in another country. "Chasing DX" means trying to contact far-away places.
EchoLink: Software that links repeaters and individual hams over the internet, letting you reach distant stations from a local radio or computer.
Elmer: An experienced ham who mentors newcomers, answering questions and helping them get on the air.
Emission: The official name for a type of signal a radio sends out (like voice FM or Morse code).
FCC: The Federal Communications Commission, the U.S. agency that licenses and regulates amateur radio.
Feed line: The cable that carries your signal between the radio and the antenna.
Field Day: An annual ARRL event each June where clubs operate from the field to practice emergency communications and have fun.
Filter: A circuit that lets the signals you want through and blocks the ones you don't.
FM: Frequency Modulation, the clear, hiss-free mode most often used on VHF/UHF repeaters and simplex.
Frequency: How many times a radio wave wiggles each second, measured in hertz — higher frequency means faster wiggles.
Gain: How much an antenna concentrates signal in a direction, making it act stronger that way.
Grid square: A short code (like EN70) that names your location on a worldwide map grid.
Grounding: Connecting equipment to the earth for safety and to reduce noise.
Harmonics: Unwanted extra signals at multiples of your frequency that can cause interference.
Hertz: The unit for counting wave wiggles per second (1 hertz = one wiggle per second).
HF: High Frequency, 3-30 MHz. These bands can travel worldwide by bouncing signals off the ionosphere.
HT (handheld): A Handheld Transceiver, a small walkie-talkie-style radio, usually for VHF/UHF.
Identify (ID): Stating your call sign on the air, required at least every 10 minutes during a contact and at the end.
Impedance: A measure of how much a circuit or antenna resists the radio signal, measured in ohms (50 ohms is standard).
Inductor: A coil of wire that stores energy in a magnetic field and resists sudden changes in current.
Insulator: A material like rubber or glass that blocks electricity.
Ionosphere: A high layer of the sky that can bounce some radio waves back to Earth, letting them travel far.
Megahertz: One million hertz — the usual way we name ham radio frequencies.
Mode: The method used to carry information on a signal, such as FM, SSB, CW, or a digital mode.
Modulation: Adding your voice or data onto a plain radio wave so it can carry information.
Net: A scheduled on-air gathering of operators, run by a moderator, for check-ins, traffic, or a common interest.
Net Control Station (NCS): The operator who runs a net, recognizing stations and keeping the conversation orderly.
Offset: The fixed frequency difference between a repeater's input and output (commonly 600 kHz on 2 meters, 5 MHz on 70 cm).
Ohm: The unit of electrical resistance.
Phonetic alphabet: Standard code words (Alpha, Bravo, Charlie...) used to spell letters clearly over the radio.
PL tone / CTCSS: A sub-audible tone your radio sends so a repeater knows to open up. CTCSS is the generic name; PL is Motorola's brand for it.
Polarization: Whether a radio wave's electric wiggle is up-and-down (vertical) or side-to-side (horizontal).
POTA (Parks on the Air): A popular program where operators ("activators") set up and make contacts from designated parks.
Propagation: How radio waves travel from one place to another.
QSL: "I acknowledge / I confirm." Also refers to a QSL card, a postcard mailed to confirm a contact.
QSO: A two-way conversation or contact between operators. "I had a QSO with a station in Ohio."
QTH: Your location. "My QTH is Indianapolis." (One of many "Q-codes" borrowed from Morse-code shorthand.)
RACES: Radio Amateur Civil Emergency Service, hams operating under the direction of a government emergency-management agency.
Rag chew: A long, casual conversation on the air, just chatting rather than a quick exchange.
Receiver: The part of a radio that picks up signals.
Repeater: An automated station, usually on a tall site, that receives your signal and rebroadcasts it to greatly extend your range.
Resistance: How much a material fights the flow of electricity, measured in ohms.
Resistor: A part that slows down electric current on purpose.
RF: Radio Frequency — the kind of fast-changing electricity that becomes radio waves.
Rig: Casual term for a radio transceiver of any kind.
Satellite: An amateur radio repeater orbiting in space that you can talk through.
Semiconductor: A material that's in between a conductor and an insulator, used to make diodes and transistors.
Simplex: Talking directly radio-to-radio on a single frequency, with no repeater in between.
Skywarn: A National Weather Service program of trained spotters, many of them hams, who report severe weather conditions.
SOTA (Summits on the Air): Like POTA, but operators hike to mountain and hill summits to make contacts.
SSB: Single Sideband, an efficient voice mode favored on HF for long-distance contacts.
SWR: Standing Wave Ratio, a measure of how well your antenna matches your radio. Lower (near 1:1) is better; high SWR can damage a transmitter.
System Fusion (C4FM): Yaesu's digital voice system. C4FM is the underlying signal format; it can also fall back to analog FM.
Technician / General / Amateur Extra: The three U.S. license classes, in order. Technician is the entry level; each higher class grants more frequency privileges, especially on HF.
Transceiver: A single radio that both transmits and receives.
Transistor: A tiny part that can switch or amplify electric signals; it's the building block of modern electronics.
Transmitter: The part of a radio that sends signals out.
Transmitter power: How many watts your radio puts out.
UHF: Ultra High Frequency, 300 MHz-3 GHz (includes the 70-centimeter band). Line-of-sight and good at penetrating buildings.
VE (Volunteer Examiner): A licensed ham accredited to administer the FCC license exams that newcomers take to get on the air.
Vertical: An antenna that stands straight up and sends signal out evenly in all directions.
VHF: Very High Frequency, 30-300 MHz (includes the popular 2-meter band). Mostly line-of-sight, great for local contacts.
Volt: The unit of electrical push (voltage).
Voltage: The electrical 'push' that moves electricity, measured in volts.
Watt: The unit of electrical power — how fast energy is used or sent.
Wavelength: The length of one full radio wave; higher frequency makes the wave shorter.
Yagi: A beam antenna with several rods that focuses your signal in one direction for more reach.

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