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Ham Radio Glossary

122 terms, jargon, and abbreviations — explained in plain English. New to the hobby? Start here.

#

73: Operating shorthand for "best regards," used to sign off.
88: Operating shorthand for "love and kisses," a warmer sign-off.

A

A-index: A daily index of geomagnetic activity (0–400); lower values mean better HF conditions.
AM (Amplitude Modulation): A voice mode in which the carrier amplitude varies; older and wider than SSB.
Amplifier (Linear): A device that boosts transmit power; a "linear" preserves the signal's shape.
Antenna: The conductor that radiates and receives RF energy — the most important part of any station.
APRS: Automatic Packet Reporting System — sends position and telemetry over VHF packet radio.
ARES: Amateur Radio Emergency Service — the ARRL's volunteer emergency-communications program.
Attenuation: Loss of signal strength — in feedline, components, or over distance.
ATU (Antenna Tuner): Matches the transmitter to the antenna system to minimize SWR; does not "tune" the antenna itself.

B

Balun: A "balanced-to-unbalanced" transformer that connects a balanced antenna (like a dipole) to coax.
Band: A range of frequencies allocated to a service, e.g., the 20-meter band (14.0–14.35 MHz).
Band plan: A voluntary convention dividing a band by mode and use to keep order.
Bandwidth: The range of frequencies a signal occupies.
Beacon: A station that transmits continuously or on a schedule to help operators gauge propagation.
Beam: A directional antenna (such as a Yagi) that concentrates energy in one direction.
Bug: A semi-automatic mechanical Morse key that makes dots automatically.

C

Callsign: Your unique, government-assigned station identifier (e.g., W1AW).
Carrier: The steady RF signal that is modulated to carry information.
Coax (Coaxial cable): Common shielded feedline such as RG-8, RG-58, or LMR-400.
Contest: An on-air competition to make the most contacts in a set period.
CQ: A general call inviting any station to answer ("seek you").
CTCSS (PL): A sub-audible tone that opens a repeater's squelch so it responds to you.
CW (Continuous Wave): Morse code, sent by keying a carrier on and off.

D

D-STAR: An Icom-led digital voice and data mode.
dB (Decibel): A logarithmic ratio of two power or voltage levels.
dBi / dBd: Antenna gain referenced to an isotropic radiator (dBi) or a dipole (dBd).
Desense: Receiver desensitization — loss of sensitivity caused by a strong nearby signal.
Dipole: A half-wave wire antenna fed in the center; the classic, simple HF antenna.
DMR: Digital Mobile Radio — a digital voice mode that uses talkgroups and networks.
Duplex: Transmitting and receiving on two different frequencies, as repeaters do.
DX: Distant stations or long-distance contacts.
DXCC: The ARRL "DX Century Club" award for confirming 100+ DXCC entities.
DXpedition: An expedition to activate a rare or uninhabited location for DX contacts.

E

Elmer: A mentor who helps newcomers learn amateur radio.
EmComm: Emergency communications.
EME (Moonbounce): Earth-Moon-Earth — communicating by bouncing signals off the Moon.
ERP / EIRP: Effective (Isotropic) Radiated Power — transmit power including antenna gain and losses.

F

Feedline: The cable connecting the radio to the antenna (coax, ladder line, etc.).
Field Day: The ARRL's big annual emergency-readiness operating event, held the fourth weekend of June.
FM (Frequency Modulation): The common VHF/UHF voice mode — clear audio but relatively wide.
FT8 / FT4: Popular weak-signal digital modes (in WSJT-X) that make quick, automated contacts.

G

Gain: How much an antenna or amplifier increases signal, often in a specific direction.
Grayline (Greyline): The twilight line between day and night, which often enhances low-band DX.
Grid square: A Maidenhead locator (e.g., FN31) that identifies your location for VHF and contests.
Ground: Connections to earth or a counterpoise for safety and RF performance.

H

Ham: An amateur radio operator.
Harmonics: Whole-number multiples of a frequency; unwanted harmonics cause interference.
HF (High Frequency): 3–30 MHz — the "shortwave" bands used for long-distance contacts.
HT (Handheld): A handheld VHF/UHF transceiver, also called a "handie-talkie."

I

Impedance: AC opposition to current (in ohms); antennas and feedlines target about 50 Ω.
Intermod (IMD): Spurious mixing products created when strong signals combine in a receiver or amplifier.
Ionosphere: The charged upper atmosphere that refracts HF signals, enabling skip propagation.
IOTA: Islands on the Air — an award program for contacting island groups.
ITU: International Telecommunication Union — sets worldwide frequency allocations and zones.

J

JS8 / JS8Call: A keyboard chat mode built on FT8 technology for weak-signal conversation.

K

K-index: A 3-hour geomagnetic activity index (0–9); low values favor good HF propagation.
Keyer: An electronic device that forms Morse dots and dashes from a paddle.

L

Ladder line: Low-loss balanced open-wire feedline.
License classes: In the US: Technician, General, and Amateur Extra — each with more privileges.
LoTW: Logbook of The World — the ARRL's electronic QSL and award-tracking system.
LSB / USB: Lower and Upper Sideband (SSB); convention is LSB below 10 MHz, USB above.

M

Maidenhead: The grid-square locator system that encodes location into letters and digits.
Mode: How information is carried — CW, SSB, FM, FT8, RTTY, etc.
MUF / LUF: Maximum and Lowest Usable Frequency for a given path and time.

N

Net: A scheduled on-air meeting run by a Net Control Station.
NVIS: Near Vertical Incidence Skywave — short-range HF using steep, near-vertical angles.

O

Offset: The transmit/receive frequency difference on a repeater (e.g., −600 kHz on 2 m).
OM: "Old Man" — any male operator, regardless of age.

P

Packet: A digital data mode (AX.25); the basis of APRS and older BBS networks.
Paddle: A lever key used with an electronic keyer to send Morse.
PEP: Peak Envelope Power — the standard measure of transmitter output power.
Pileup: Many stations calling one station (such as a DXpedition) at the same time.
POTA: Parks on the Air — a program for activating and "hunting" parks.
Propagation: How radio waves travel from transmitter to receiver.
PSK31: A narrow keyboard-to-keyboard digital text mode popular on HF.

Q

QRM: Man-made interference.
QRN: Natural noise or static.
QRO: High power operation.
QRP: Low-power operation — 5 watts output or less.
QRZ: "Who is calling me?"
QSB: Signal fading.
QSL: Confirmation of a contact — and the postcard ("QSL card") that confirms it.
QSO: A two-way contact or conversation.
QSY: To change frequency.
QTH: Your station location.

R

Ragchew: A long, relaxed on-air conversation.
Repeater: A station that receives and re-transmits signals to extend the range of mobiles and HTs.
RF: Radio Frequency — alternating electrical energy in the radio range.
Rig: A radio or transceiver.
Rotator: A motor that rotates a beam antenna to point it.
RST: A signal report: Readability (1–5), Strength (1–9), and Tone (1–9, CW) — e.g., "599."
RTTY: Radioteletype — a classic FSK digital text mode used in contests.

S

SDR: Software-Defined Radio — a radio whose functions are largely defined in software.
Shack: Your radio operating room or space.
Simplex: Transmitting and receiving on the same frequency, directly (no repeater).
SK: "Silent Key" — a deceased amateur; also the CW prosign that ends a contact.
Skip: HF signals refracted by the ionosphere to reach far beyond the horizon.
SOTA: Summits on the Air — a program for operating from mountain summits.
Split: Transmitting and receiving on different frequencies — common when working DX.
Sporadic E (Es): Patchy ionization in the E layer that enables surprise openings on 6 m and upper HF.
SSB (Single Sideband): The efficient HF voice mode; uses one sideband and suppresses the carrier.
SSTV: Slow-Scan Television — sending still images over the radio as audio tones.
SWL: Shortwave Listener — someone who listens but may not transmit.
SWR (VSWR): Standing Wave Ratio — how well the antenna system is matched; 1:1 is ideal.
System Fusion: Yaesu's C4FM digital voice and data system.

T

Transceiver: A combined transmitter and receiver in one unit.
Transverter: A converter that shifts a radio's band to another (e.g., an HF rig onto VHF).

U

UHF: Ultra High Frequency — 300 MHz to 3 GHz (e.g., the 70 cm band).
Unun: An "unbalanced-to-unbalanced" impedance transformer, common with end-fed antennas.
UTC (Zulu): Coordinated Universal Time — the standard time reference used in logging ("Z").

V

VE: Volunteer Examiner — a licensed ham accredited to administer license exams.
Velocity factor: How much slower RF travels in a cable compared with free space (e.g., 0.66 for RG-58).
VFO: Variable Frequency Oscillator — sets your operating frequency.
VHF: Very High Frequency — 30 to 300 MHz (e.g., the 2 m band).

W

WAS: Worked All States — an award for confirming contacts with all 50 US states.
Wavelength: The physical length of one RF cycle; λ (meters) ≈ 300 ÷ frequency (MHz).
WSPR: Weak Signal Propagation Reporter ("whisper") — beacon mode for studying propagation.
WWFF: World Wide Flora & Fauna — an award program for activating protected nature areas.

X

XYL: A ham's wife (originally "ex-young-lady").

Y

Yagi: A directional beam antenna with a driven element plus parasitic reflectors and directors.
YL: "Young Lady" — any female operator, regardless of age.