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Quick reference

Glossary

147 terms and abbreviations you will meet on the air and on the exams, each with its sources and the questions that use it. Site search also answers these terms directly.

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A

A index

Propagation

A measure of the long-term stability of Earth’s geomagnetic field, derived from the three-hourly K values. A rising A index means increasing disturbance.

Also written: A-index, Ap, Ap index

Learn more: When the Sun misbehaves

On the exams: G3A13, E3C02, E3C03

Related: K index, Geomagnetic storm

Sources: 2023-2027 General question pool, question G3A13 (NCVEC Question Pool Committee); Space Weather Glossary (NOAA Space Weather Prediction Center); 2024-2028 Extra question pool, question E3C02 (NCVEC Question Pool Committee)

ALC Automatic level control

Equipment

A control loop that limits transmitter drive. With an RF power amplifier it prevents excessive drive; on SSB it is set with the transmit audio or microphone gain; and it should be inactive when sending AFSK data, because its action distorts the signal.

Also written: automatic level control

On the exams: G2A12, G4A05, G4A11

Related: Amplifier, SSB

Sources: 2023-2027 General question pool, question G4A05 (NCVEC Question Pool Committee); 2023-2027 General question pool, question G2A12 (NCVEC Question Pool Committee); 2023-2027 General question pool, question G4A11 (NCVEC Question Pool Committee)

AM Amplitude modulation

Modes

Modulation that varies the amplitude of a radio carrier with the voice or other signal. Double-sideband AM is what broadcast stations use; single sideband is a variation. Band plans list AM calling frequencies on several HF bands.

Also written: amplitude modulation, double sideband

Also used in: Operating on HF, Logging and confirming contacts, How radio signals travel, RF exposure and your station

On the exams: T7B02, T8A01, T8A10, G8A05, G8A11, E2B06, E4E11, E8C01

Related: SSB, FM

Sources: Ham Radio Glossary (ARRL); Band Plan (ARRL)

Amplifier External RF power amplifier

Equipment

A device that increases a transmitter’s power output when used with it but is not built into it. Automatic level control (ALC) from the amplifier prevents excessive drive.

Also written: linear amplifier, linear, amp, external RF power amplifier, power amplifier

On the exams: T7A10, G4A04, G4A05, G4A08, G7B08, E1F03, E1F11, E7B05

Related: ALC, PEP

Sources: 47 CFR 97.3, Definitions (eCFR); Choosing a Ham Radio (Ham Radio License Manual supplement) (ARRL); 2023-2027 General question pool, question G4A05 (NCVEC Question Pool Committee)

Antenna tuner

Antennas and feed lines

A device that matches the impedance of the antenna system to the transceiver’s output impedance, also called an antenna coupler or Transmatch. It does not tune the antenna itself, and a tuner at the transmitter does not change the SWR on the feed line between the tuner and the antenna. Many HF radios have an automatic tuner (ATU) built in.

Also written: ATU, automatic antenna tuner, antenna coupler, tuner, Transmatch, impedance matching unit, impedance-matching network, matching network

Learn more: Antenna tuners, Matching network designer

Also used in: Choosing your first radio

On the exams: T9B04, G4A06, G9A08

Related: SWR, EFHW, Balun

Sources: 2026-2030 Technician question pool, question T9B04 (NCVEC Question Pool Committee); Ham Radio Glossary (ARRL); Choosing a Ham Radio (Ham Radio License Manual supplement) (ARRL); 2023-2027 General question pool, question G9A08 (NCVEC Question Pool Committee)

APRS Automatic Packet Reporting System

Modes

A packet radio system that carries GPS positions, text messages and weather data, used for real-time tactical communications and for tracking balloons. It uses the AX.25 protocol and relays data through digipeaters; the IARU Region 2 band plan puts its center of activity at 144.390 MHz.

Also written: Automatic Packet Reporting System, 144.39, 144.390

Learn more: Packet and APRS, 2 m band plan

Also used in: Working amateur satellites

On the exams: T8D03, T8D05, E2D04, E2D07, E2D08, E2D11

Related: Packet radio, Digipeater

Sources: Choosing a Ham Radio (Ham Radio License Manual supplement) (ARRL); 2026-2030 Technician question pool, question T8D03 (NCVEC Question Pool Committee); 2026-2030 Technician question pool, question T8D05 (NCVEC Question Pool Committee); 2024-2028 Extra question pool, question E2D04 (NCVEC Question Pool Committee); 2024-2028 Extra question pool, question E2D07 (NCVEC Question Pool Committee); 2024-2028 Extra question pool, question E2D11 (NCVEC Question Pool Committee); IARU Region 2 Band Plan (September 2020) (IARU Region 2)

ARES Amateur Radio Emergency Service

Public service

Licensed amateurs who have registered their qualifications and equipment with their local ARES leadership to provide public service communications when disaster strikes. Any licensed amateur may apply.

Also written: Amateur Radio Emergency Service

Learn more: ARES

Also used in: What is amateur radio?, Your first month on the air, Clubs, mentors and nets, Connectors and cables

On the exams: T2C06

Related: RACES, SKYWARN, NTS, Winlink

Sources: ARES (ARRL)

ARISS Amateur Radio on the International Space Station

Satellites

The program that arranges amateur radio contacts between crew members on the International Space Station and schools, education organizations and other groups.

Also written: Amateur Radio on the International Space Station, ISS

Learn more: The ISS and ARISS

Also used in: What is amateur radio?

On the exams: T1B02

Related: Uplink and downlink

Sources: ARISS home page (ARISS)

Aurora

Propagation

Severe geomagnetic storms create auroras that can reflect VHF signals. Signals by aurora sound distorted and raspy, and CW works best for this kind of propagation.

Also written: auroral propagation, auroral backscatter

Also used in: Radio waves and the spectrum, How radio signals travel

On the exams: T3C03, E3A12, E3A13, E3C03

Related: Geomagnetic storm

Sources: 2023-2027 General question pool, question G3A09 (NCVEC Question Pool Committee); 2024-2028 Extra question pool, question E3A12 (NCVEC Question Pool Committee); 2026-2030 Technician question pool, question T3C03 (NCVEC Question Pool Committee); 2024-2028 Extra question pool, question E3A13 (NCVEC Question Pool Committee)

B

Bandwidth

Rules and licensing

In Part 97, the width of the frequency band outside which the transmitted signal’s mean power is at least 26 dB below its mean power inside the band.

Also written: occupied bandwidth

On the exams: G1C03, E1B02, E1C01

Related: Spurious emission

Sources: 47 CFR 97.3, Definitions (eCFR)

Beacon

Operating

An amateur station that transmits so others can observe propagation and reception. Beacon stations are limited to 100 W PEP output. International Beacon Project (IBP) beacons transmit on 14.100, 18.110, 21.150, 24.930 and 28.200 MHz.

Also written: beacon station, propagation beacon, NCDXF beacons, International Beacon Project, IBP

Learn more: HF beacon tracker

On the exams: T1A06, G1B02, G1B03, G1B09, G1B10, G1E10, E1D12

Related: WSPR

Sources: 47 CFR 97.3, Definitions (eCFR); 2023-2027 General question pool, question G1B10 (NCVEC Question Pool Committee); IARU Region 2 Band Plan (September 2020) (IARU Region 2); Band Plan (ARRL)

C

Call sign

Rules and licensing

The letters and numbers that identify an amateur station. The FCC assigns one from a sequential list by region and license class, or you can request a vanity call sign; special event call signs such as K1A are used for events.

Also written: callsign, vanity call sign, vanity call, special event call sign, sequential call sign

Learn more: Wait for your call sign, Phonetic speller

Also used in: What is amateur radio?, License classes and privileges, Choosing your first radio, Your first month on the air, Programming a radio

On the exams: T1A04, T1C02, T1C05, T1F02, T1F03, T1F05, T2A04, T2A05 and 12 more

Related: Station identification, ULS, Phonetic alphabet

Sources: Ham Radio Glossary (ARRL); 47 CFR 97.3, Definitions (eCFR)

Coax Coaxial cable

Antennas and feed lines

Feed line with one conductor inside the other. It is the most common amateur feed line because it is easy to use and needs few special installation considerations, and most amateur coax has a 50-ohm impedance. Moisture getting in is a common cause of failure, and foam-dielectric coax has less loss per foot than solid-dielectric coax.

Also written: coaxial cable, coaxial, hardline

Learn more: Choosing coax, Coax and other feed lines

Also used in: Choosing your first radio, Emergency communications, Putting up antennas

On the exams: T7C10, T7C11, T9B03, T9B05, T9B07, T9B10, G4B13, G5C07 and 6 more

Related: Ladder line, Velocity factor, SWR, Feed line

Sources: Ham Radio Glossary (ARRL); 2026-2030 Technician question pool, question T9B03 (NCVEC Question Pool Committee); 2026-2030 Technician question pool, question T9B02 (NCVEC Question Pool Committee); 2026-2030 Technician question pool, question T7C09 (NCVEC Question Pool Committee); 2026-2030 Technician question pool, question T7C11 (NCVEC Question Pool Committee)

Common-mode current

Electronics

Current that flows equally on all conductors of a cable, or on the outside of a coax shield, and can make cables radiate or pick up interference. A ferrite bead or core reduces it by adding impedance in its path.

Also written: common mode, ferrite choke, choke, ferrite bead

Also used in: Putting up antennas

On the exams: T7B11, G4C08, G6B01, G6B05, G6B10, E4E04, E4E07, E4E08 and 2 more

Related: RFI, Balun

Sources: 2024-2028 Extra question pool, question E4E08 (NCVEC Question Pool Committee); 2024-2028 Extra question pool, question E4E07 (NCVEC Question Pool Committee); 2023-2027 General question pool, question G6B10 (NCVEC Question Pool Committee)

Control operator

Rules and licensing

The licensed amateur responsible for making a station’s transmissions follow the rules. The control point is where the control operator function is performed: at the station (local control) or through a control link such as the internet (remote control). Under automatic control, devices and procedures keep the station within the rules without the control operator being present at a control point.

Also written: control point, local control, remote control, automatic control

Learn more: Control operators and control points

Also used in: License classes and privileges, Choosing your first radio, Emergency communications

On the exams: T1A10, T1D08, T1E01, T1E02, T1E03, T1E04, T1E05, T1E06 and 17 more

Related: Part 97, Third-party communications

Sources: 47 CFR 97.3, Definitions (eCFR); 2026-2030 Technician question pool, question T1E10 (NCVEC Question Pool Committee)

CQ Calling any station

Operating

The general call meaning calling any station. A station in the 48 contiguous states calling CQ DX is asking for replies only from stations outside the lower 48 states.

Also written: calling CQ, CQ DX

Learn more: Calling CQ and answering

Also used in: Digital modes, Learning Morse code, Working amateur satellites, How radio signals travel

On the exams: T2A05, T2A06, T2A08, T4B06, G2A11, G2B06, G2C05, G2D05 and 2 more

Related: DX, QSO

Sources: 2026-2030 Technician question pool, question T2A08 (NCVEC Question Pool Committee); Ham Radio Glossary (ARRL); 2023-2027 General question pool, question G2A11 (NCVEC Question Pool Committee)

Critical frequency

Propagation

The highest frequency that a layer of the ionosphere returns to Earth when the wave goes straight up (vertical incidence); higher frequencies pass through the layer. For the F2 layer it is written foF2. The General pool (G3C02) uses the term for the highest frequency refracted back at a given incidence angle.

Also written: foF2

Learn more: Propagation conditions

Also used in: How radio signals travel

On the exams: G3C02

Related: MUF, Ionosphere, NVIS

Sources: Space Weather Glossary (NOAA Space Weather Prediction Center); 2023-2027 General question pool, question G3C02 (NCVEC Question Pool Committee)

CTCSS Continuous tone-coded squelch system

Operating

A sub-audible tone sent along with your voice that opens the squelch of a receiver, used by many repeaters to accept only signals that carry the right tone. Also called PL. Using the wrong CTCSS tone is one reason you may hear a repeater but be unable to use it.

Also written: PL, PL tone, sub-audible tone, subaudible tone

Learn more: Tones and codes, Access tones

Also used in: Choosing your first radio, Working amateur satellites, Antennas and feed lines, Connectors and cables

On the exams: T2B02, T9B07

Related: DCS, Repeater, Squelch, DTMF

Sources: 2026-2030 Technician question pool, question T2B02 (NCVEC Question Pool Committee); Ham Radio Glossary (ARRL); 2026-2030 Technician question pool, question T2B04 (NCVEC Question Pool Committee)

CW Continuous wave (Morse code telegraphy)

Modes

Morse code sent by switching a radio signal on and off. Part 97 defines CW as international Morse code telegraphy emissions. CW is narrower than FM voice, SSB voice or slow-scan TV.

Also written: Morse code, continuous wave, Morse, telegraphy

Learn more: Learning Morse code, Morse code trainer

Also used in: License classes and privileges, Choosing your first radio, Rules on the air, Operating on HF, Digital modes

On the exams: T1B07, T1F05, T3A03, T7A09, T8A05, T8A11, T8D09, G1A07 and 19 more

Related: QRP, RST

Sources: Ham Radio Glossary (ARRL); 47 CFR 97.3, Definitions (eCFR); 2026-2030 Technician question pool, question T8A05 (NCVEC Question Pool Committee)

D

dBi and dBd Antenna gain in decibels relative to an isotropic antenna or a half-wave dipole

Antennas and feed lines

Antenna gain stated relative to an isotropic antenna (dBi) or to a half-wave dipole (dBd). The same gain is 2.15 dB higher when stated in dBi than in dBd.

Also written: dBi, dBd, isotropic gain, antenna gain

Learn more: Gain and directivity, Decibels

Also used in: Operating on HF, RF exposure and your station

On the exams: G9C04, E4D12, E4D13, E9A02, E9A06, E9A07

Related: ERP, EIRP, Decibel

Sources: 47 CFR 97.3, Definitions (eCFR); 2023-2027 General question pool, question G9C04 (NCVEC Question Pool Committee)

Decibel dB

Electronics

A logarithmic way of comparing two signal strengths. Doubling power is about 3 dB, quartering it is about -6 dB, and ten times the power is 10 dB. dBm is a power level in decibels compared with one milliwatt.

Also written: dB, decibels, dBm, 3 dB

Learn more: Decibels, Decibels

On the exams: T5B09, T5B10, T5B11

Related: dBi and dBd, S meter

Sources: Choosing a Ham Radio (Ham Radio License Manual supplement) (ARRL); 2026-2030 Technician question pool, question T5B09 (NCVEC Question Pool Committee); 2026-2030 Technician question pool, question T5B10 (NCVEC Question Pool Committee); 2026-2030 Technician question pool, question T5B11 (NCVEC Question Pool Committee); Radio Mathematics (ARRL Handbook supplement) (ARRL)

Digital voice

Modes

Voice modes that send speech as digital data. DMR, D-STAR and System Fusion are common examples. On DMR you join a talkgroup by programming its ID or code into your radio, and a repeater’s color code is an access code your radio must match.

Also written: DMR, D-STAR, DSTAR, System Fusion, SystemFusion, Fusion, talkgroup, color code

Learn more: Digital voice, Single band, dual band and digital voice

Also used in: Programming a radio

On the exams: T2B12, T2B14, T4A10, T4B07, T4B09, T4B11, T8D07, G8C16 and 1 more

Related: Hotspot, Repeater

Sources: 2023-2027 General question pool, question G8C16 (NCVEC Question Pool Committee); 2026-2030 Technician question pool, question T2B07 (NCVEC Question Pool Committee); 2026-2030 Technician question pool, question T4B09 (NCVEC Question Pool Committee); 2026-2030 Technician question pool, question T2B12 (NCVEC Question Pool Committee)

Dipole Half-wave dipole antenna

Antennas and feed lines

A basic wire or tubing antenna, usually a half wavelength long and fed at the center. It radiates most strongly broadside to its length, and in free space its pattern is a figure eight at right angles to the wire. Shortening a dipole raises its resonant frequency.

Also written: half-wave dipole, half wave dipole, dipole antenna

Learn more: The half-wave dipole, Antenna length calculator

Also used in: License classes and privileges, Choosing your first radio, Operating on HF, Logging and confirming contacts, Radio waves and the spectrum

On the exams: T9A05, T9A10, G1C04, G9B04, G9B05, G9B07, G9B08, G9B10 and 9 more

Related: EFHW, OCFD, Folded dipole, NVIS

Sources: Ham Radio Glossary (ARRL); 2026-2030 Technician question pool, question T9A10 (NCVEC Question Pool Committee); 2023-2027 General question pool, question G9B04 (NCVEC Question Pool Committee); 2026-2030 Technician question pool, question T9A05 (NCVEC Question Pool Committee)

DTMF Dual-tone multi-frequency

Operating

Signaling with two simultaneous audio tones, the same as telephone keypad tones. Repeaters and IRLP nodes use DTMF for control and access.

Also written: touch tones, touchtone, dual tone multi frequency

Also used in: Making your first contact

On the exams: T2B06, T8C06

Related: Repeater, IRLP

Sources: 2026-2030 Technician question pool, question T2B06 (NCVEC Question Pool Committee); 2026-2030 Technician question pool, question T8C06 (NCVEC Question Pool Committee)

Dummy load

Equipment

A station accessory for testing and adjusting a transmitter without sending a signal over the air. A typical RF dummy load is a 50-ohm non-inductive resistor on a heat sink.

Also written: dummy antenna

Also used in: Antennas and feed lines, Building your own gear

On the exams: T7C01, T7C03, G5B06, G5B12

Related: SWR

Sources: 2026-2030 Technician question pool, question T7C01 (NCVEC Question Pool Committee); 2026-2030 Technician question pool, question T7C03 (NCVEC Question Pool Committee); Ham Radio Glossary (ARRL)

E

EFHW End-fed half-wave antenna

Antennas and feed lines

A half-wavelength wire antenna fed at one end instead of the center. The feed point impedance at the end of a half-wave antenna is very high, far from the 50 ohms of common coax, so an end-fed half-wave needs impedance matching between the antenna and the feed line. A half-wave antenna fed at one end is also called a Zepp.

Also written: end-fed half-wave, end-fed half-wavelength, end-fed, end fed half wave antenna, half-wave end-fed

Learn more: Antenna length calculator, end-fed half-wave mode

On the exams: G9D02, E9C10

Related: Dipole, Zepp, Antenna tuner, SWR

Sources: 2023-2027 General question pool, question G9D02 (NCVEC Question Pool Committee); 2026-2030 Technician question pool, question T9B02 (NCVEC Question Pool Committee); 2023-2027 General question pool, question G9A04 (NCVEC Question Pool Committee); 2024-2028 Extra question pool, question E9C10 (NCVEC Question Pool Committee)

EIRP Equivalent isotropically radiated power

Rules and licensing

The power supplied to the antenna multiplied by the antenna’s gain relative to an isotropic antenna, in a given direction. Divide EIRP by 1.64 to get ERP.

Also written: equivalent isotropically radiated power, effective isotropic radiated power

Learn more: Decibels, RF exposure evaluator

Also used in: Antennas and feed lines

On the exams: E1A07, E1A09, E9A07

Related: ERP, dBi and dBd

Sources: 47 CFR 97.3, Definitions (eCFR); 2024-2028 Extra question pool, question E9A07 (NCVEC Question Pool Committee)

ERP Effective radiated power

Rules and licensing

The power supplied to the antenna multiplied by the antenna’s gain relative to a half-wave dipole, in a given direction. Multiply ERP by 1.64 to get EIRP.

Also written: effective radiated power

Learn more: Decibels, RF exposure evaluator

Also used in: License classes and privileges, Operating on HF, Antennas and feed lines, RF exposure and your station

On the exams: T8B02, E2A08, E9A02, E9A03, E9A06

Related: EIRP, dBi and dBd, PEP

Sources: 47 CFR 97.3, Definitions (eCFR); 2024-2028 Extra question pool, question E9A02 (NCVEC Question Pool Committee)

Exam element

Rules and licensing

One of the written license exams. Element 2 (Technician) and Element 3 (General) have 35 questions with 26 needed to pass; Element 4 (Amateur Extra) has 50 questions with 37 needed. Technician requires Element 2, General Elements 2 and 3, and Amateur Extra Elements 2, 3 and 4.

Also written: element 2, element 3, element 4, license exam, passing score

Learn more: Exam prep

Related: Question pool, CSCE

Sources: 47 CFR 97.501, Qualifying for an amateur operator license (eCFR); 47 CFR 97.503, Element standards (eCFR)

F

FM Frequency modulation

Modes

Modulation that varies the frequency of a radio carrier with the voice or other signal. It is the voice mode used on most repeaters.

Also written: frequency modulation, FM phone

Learn more: Simplex and repeaters

Also used in: What is amateur radio?, License classes and privileges, Choosing your first radio, Programming a radio, Working amateur satellites

On the exams: T2A02, T2B05, T4A01, T4B03, T4B04, T4B05, T7A09, T7B01 and 25 more

Related: Repeater, Simplex, AM

Sources: Ham Radio Glossary (ARRL)

FT8

Modes

A digital mode that works at very low signal-to-noise ratios. It uses 8-tone frequency shift keying, 15-second transmit cycles and about 50 Hz of bandwidth, and needs computer time accurate to about one second. On 20 m it is commonly found from about 14.074 to 14.077 MHz.

Also written: FT-8

Learn more: FT8 and FT4, 20 m band

Also used in: What is amateur radio?, Choosing your first radio, How radio signals travel

On the exams: T1B05, T4A04, T8D02, G2E04, G2E05, G2E07, G2E15, G8A09 and 6 more

Related: WSPR, SSB, Grid square

Sources: 2026-2030 Technician question pool, question T8D02 (NCVEC Question Pool Committee); 2023-2027 General question pool, question G8A09 (NCVEC Question Pool Committee); 2024-2028 Extra question pool, question E2E06 (NCVEC Question Pool Committee); 2024-2028 Extra question pool, question E8C06 (NCVEC Question Pool Committee); 2023-2027 General question pool, question G2E07 (NCVEC Question Pool Committee); 2023-2027 General question pool, question G2E15 (NCVEC Question Pool Committee)

G

Geomagnetic storm

Propagation

A temporary disturbance of Earth’s magnetic field. It can degrade HF propagation at high latitudes, and severe storms can produce auroras that reflect VHF signals.

Also written: magnetic storm, G scale

Learn more: When the Sun misbehaves, Propagation conditions

On the exams: G3A06, G3A08, E3C08

Related: K index, A index, Aurora

Sources: 2023-2027 General question pool, question G3A06 (NCVEC Question Pool Committee); 2023-2027 General question pool, question G3A08 (NCVEC Question Pool Committee); 2023-2027 General question pool, question G3A09 (NCVEC Question Pool Committee)

Grid square Maidenhead locator

Operating

A code in the Maidenhead Locator System that describes a location: two letters for the field and two numbers for the square, as in FN31, about 70 by 100 miles in the continental US. Two more letters, as in FN44ig, give a subsquare. Most contacts at the low end of the VHF bands include grid squares, and in an FT8 or FT4 VHF contest the grid square replaces the signal report.

Also written: Maidenhead locator, Maidenhead, grid locator, locator, grid

Learn more: Grid square locator

Also used in: Working amateur satellites, How radio signals travel

On the exams: E2D02

Related: FT8

Sources: Grid Squares (ARRL); 2024-2028 Extra question pool, question E2D02 (NCVEC Question Pool Committee)

Grounding and bonding

Safety

Connecting station equipment together and to an earth ground for safety and performance. Flat copper strap is preferred for RF bonding, and a single-point ground panel makes all lightning protectors act at the same time.

Also written: bonding, grounding, ground rod, single point ground, station ground

Learn more: Lightning protection where the coax comes in, Grounding and bonding

On the exams: T4A08, G4C11, E4E13, E4E14

Related: GFCI

Sources: Ham Radio Glossary (ARRL); 2026-2030 Technician question pool, question T4A08 (NCVEC Question Pool Committee); 2024-2028 Extra question pool, question E4E14 (NCVEC Question Pool Committee)

H

I

Impedance

Electronics

Opposition to alternating current, including resistance and reactance. Ideally a feed line’s characteristic impedance matches both the transmitter output and the antenna input; a difference between feed line and antenna impedance causes reflected power.

Also written: Z, characteristic impedance

Learn more: Reactance and resonance

Also used in: Choosing your first radio, Antennas and feed lines, Electronics basics, Building your own gear, Putting up antennas

On the exams: T5C05, T5C12, T7C04, T7C06, T9B02, T9B04, G4B05, G4B13 and 59 more

Related: SWR, Antenna tuner, Resonance

Sources: Ham Radio Glossary (ARRL); 2023-2027 General question pool, question G9A04 (NCVEC Question Pool Committee)

Ionosphere

Propagation

A region of ionized gas high in the atmosphere that bends radio waves back to Earth. The lowest D region mainly absorbs signals, especially below about 7.5 MHz in daylight; the E region exists only by day; the F region, made of the F1 and F2 regions, returns HF signals to Earth, and one F2 hop can cover up to about 2,500 miles.

Also written: D region, E region, F region, F2 region, D layer, E layer, F layer, F2 layer

Learn more: The ionosphere, Propagation conditions

Also used in: What is amateur radio?, License classes and privileges, Choosing your first radio, Making your first contact, Radio waves and the spectrum

On the exams: T3A08, T3A09, T3A11, T3C01, T3C09, T3C10, G3B05, G3B10 and 5 more

Related: Skywave, MUF, Sporadic E, Critical frequency

Sources: Ham Radio Glossary (ARRL); 2023-2027 General question pool, question G3B09 (NCVEC Question Pool Committee)

J

K

K index K index and planetary Kp index

Propagation

A measure of the short-term stability of Earth’s geomagnetic field, reported every three hours. Kp, the planetary K index, averages several observatories and is used to rate geomagnetic storms: Kp 5 is a G1 storm, Kp 8 and 9- are G4, and only the top value, 9o, is G5. A rising K index means increasing disturbance.

Also written: K-index, Kp, Kp index, planetary K index

Learn more: When the Sun misbehaves, Propagation conditions

On the exams: G3A12, E3C02, E3C03

Related: A index, Geomagnetic storm, Solar flux index

Sources: 2023-2027 General question pool, question G3A12 (NCVEC Question Pool Committee); Space Weather Glossary (NOAA Space Weather Prediction Center); Planetary K-index (NOAA Space Weather Prediction Center); 2024-2028 Extra question pool, question E3C02 (NCVEC Question Pool Committee)

L

Ladder line Parallel-conductor feed line

Antennas and feed lines

Feed line made of two parallel wires. Its characteristic impedance depends on the spacing and size of the conductors; window line is nominally 450 ohms. Parallel-conductor line has lower loss than coax with a plastic dielectric.

Also written: window line, open-wire line, parallel conductor feed line, parallel-wire line

Learn more: Coax and other feed lines

Also used in: Connectors and cables

On the exams: G9A01, G9A03, E9C09, E9F06, E9F07

Related: Coax, Balun, G5RV

Sources: Choosing a Ham Radio (Ham Radio License Manual supplement) (ARRL); 2023-2027 General question pool, question G9A01 (NCVEC Question Pool Committee); 2023-2027 General question pool, question G9A03 (NCVEC Question Pool Committee); 2024-2028 Extra question pool, question E9F07 (NCVEC Question Pool Committee)

Linear transponder

Satellites

A satellite system that can relay FM, CW, SSB, SSTV, PSK and packet signals from its uplink to its downlink. When your uplink power is right, your downlink signal is about as strong as the satellite’s beacon.

Also written: transponder, inverting transponder

Learn more: Linear transponders

On the exams: T8B12, E2A02, E2A03, E2A07, E2A08

Related: Uplink and downlink

Sources: 2024-2028 Extra question pool, question E2A07 (NCVEC Question Pool Committee); 2026-2030 Technician question pool, question T8B12 (NCVEC Question Pool Committee)

Long path

Propagation

Working a station the long way around the Earth. A directional antenna points 180 degrees from the short-path heading, and signals arriving by both paths can produce a slight echo.

Also written: long-path, short path, short-path

Learn more: Grid square locator (bearings)

On the exams: G2D06, G3B01, E3B06

Related: DX

Sources: 2023-2027 General question pool, question G2D06 (NCVEC Question Pool Committee); 2023-2027 General question pool, question G3B01 (NCVEC Question Pool Committee)

LUF Lowest usable frequency

Propagation

The lowest frequency usable for communication between two particular points. Signals below the LUF are absorbed before they reach the destination, and when the LUF rises above the MUF, ordinary sky-wave communication on that path is not possible.

Also written: lowest usable frequency

Learn more: Skip, the skip zone and the MUF

On the exams: G3B05, G3B06, G3B07, G3B11

Related: MUF

Sources: 2023-2027 General question pool, question G3B07 (NCVEC Question Pool Committee); 2023-2027 General question pool, question G3B06 (NCVEC Question Pool Committee); 2023-2027 General question pool, question G3B11 (NCVEC Question Pool Committee)

M

Meteor scatter

Propagation

Propagation using the line of ionized gas a meteor leaves in the E region of the ionosphere. Frequencies from 28 to 148 MHz suit it, 6 m in particular, and MSK144 is a digital mode designed for it.

Also written: MSK144, meteor burst

Also used in: How radio signals travel

On the exams: T3C07, E2D01, E3A09

Related: EME, FT8

Sources: 2024-2028 Extra question pool, question E3A08 (NCVEC Question Pool Committee); 2024-2028 Extra question pool, question E3A09 (NCVEC Question Pool Committee); 2026-2030 Technician question pool, question T3C07 (NCVEC Question Pool Committee); 2024-2028 Extra question pool, question E2D01 (NCVEC Question Pool Committee)

MPE Maximum permissible exposure

Safety

The FCC limits on human exposure to RF fields. Limits are lower for the general public and neighbors (uncontrolled environment) than for people who know about the exposure and can control it (controlled environment). A licensee may evaluate members of the household against the controlled limits only when they have had appropriate RF exposure training and information (97.13(c)(1)). Power density limits are lowest from 30 to 300 MHz, which is why 50 MHz has a lower limit than 3.5, 440 or 1296 MHz.

Also written: maximum permissible exposure, RF exposure, RF safety, controlled environment, uncontrolled environment

Learn more: RF exposure evaluator, Maximum permissible exposure

On the exams: T0C02, G0A11, E0A02, E0A04, E0A06

Related: Duty cycle, ERP

Sources: 47 CFR 1.1310, Radiofrequency radiation exposure limits (eCFR); 47 CFR 97.13, Restrictions on station location (eCFR); Ham Radio Glossary (ARRL); 2026-2030 Technician question pool, question T0C02 (NCVEC Question Pool Committee); 2024-2028 Extra question pool, question E0A02 (NCVEC Question Pool Committee)

MUF Maximum usable frequency

Propagation

The highest frequency that will reach a particular destination by sky wave. Signals just below the MUF have the least attenuation for long-distance skip.

Also written: maximum usable frequency, maximum useable frequency

Learn more: Skip, the skip zone and the MUF, Propagation conditions

Also used in: What is amateur radio?, License classes and privileges

On the exams: G3B02, G3B03, G3B05, G3B08, G3B11, E3A06

Related: LUF, Critical frequency, Solar flux index

Sources: 2023-2027 General question pool, question G3B08 (NCVEC Question Pool Committee); Ham Radio Glossary (ARRL); 2023-2027 General question pool, question G3B03 (NCVEC Question Pool Committee)

N

NTS National Traffic System

Public service

The ARRL system of operators trained in traffic handling, who pass formal written messages called radiograms through nets at the local, section, region and area levels. In emergencies, radiograms carry information critical to saving lives or property, or ask about the welfare of disaster victims.

Also written: National Traffic System, traffic handling, radiogram, radiograms

Learn more: The National Traffic System

Also used in: Clubs, mentors and nets

On the exams: T2C11

Related: Net, Third-party communications, ARES

Sources: National Traffic System (ARRL); Ham Radio Glossary (ARRL)

NVIS Near vertical incidence skywave

Propagation

Short-distance MF or HF propagation using radio waves sent up at high elevation angles and returned by the ionosphere. A horizontal dipole between 1/10 and 1/4 wavelength above the ground works well for NVIS.

Also written: near vertical incidence skywave, near-vertical incidence sky wave

Learn more: Day and night by band

On the exams: G3C10, G9D01

Related: Skywave, Dipole, Skip zone

Sources: 2023-2027 General question pool, question G3C10 (NCVEC Question Pool Committee); 2023-2027 General question pool, question G9D01 (NCVEC Question Pool Committee)

O

OCFD Off-center-fed dipole

Antennas and feed lines

A dipole fed between its center and one end instead of at the middle. Moving the feed point this way gives a similar feed point impedance on several bands.

Also written: off-center-fed dipole, off center fed dipole, off-center fed

On the exams: E9C05

Related: Dipole

Sources: 2024-2028 Extra question pool, question E9C05 (NCVEC Question Pool Committee)

P

Part 97 47 CFR Part 97, the FCC amateur radio rules

Rules and licensing

The FCC rules for the amateur radio services, in Title 47 of the Code of Federal Regulations. The amateur service exists for self-training, intercommunication and technical investigation by people interested in radio technique for personal reasons and not for pay.

Also written: 47 CFR Part 97, FCC rules, amateur rules

Learn more: Rules on the air

Also used in: What is amateur radio?, How to get your license, Radio waves and the spectrum, Antennas and feed lines, Building your own gear

On the exams: T1A07, T1E10, T1E11, T2C01, T2C04, G1B11, E1E01, E1E02

Related: Control operator, Station identification

Sources: 47 CFR Part 97, Amateur Radio Service (eCFR); 47 CFR 97.3, Definitions (eCFR)

PEP Peak envelope power

Rules and licensing

The average power a transmitter supplies to the feed line during one RF cycle at the crest of the modulation envelope. Most FCC transmitter power limits are stated as PEP output, but some are limits on radiated power instead: ERP on 60 m and EIRP on 2200 m, 630 m and 4 mm (97.313).

Also written: peak envelope power

Learn more: Power limits

Also used in: Choosing your first radio, Operating on HF, Connectors and cables

On the exams: T1B11, T1B12, G1B10, G1C01, G1C02, G1C05, G1C06, G1C11 and 7 more

Related: ERP, EIRP

Sources: 47 CFR 97.3, Definitions (eCFR); 2023-2027 General question pool, question G1C11 (NCVEC Question Pool Committee); 47 CFR 97.313, Transmitter power standards (eCFR)

Phonetic alphabet

Operating

Standard words for letters, such as Kilo Alfa Six for KA6, that make call signs clear on voice. The FCC encourages phonetics when identifying on phone.

Also written: phonetics, ITU phonetic alphabet, Alfa Bravo Charlie

Learn more: Phonetic alphabet, Phonetic speller

Also used in: Your first month on the air, Making your first contact, Rules on the air, Operating on HF, Emergency communications

On the exams: T1A03, T2C03, G2D07

Related: Call sign

Sources: Ham Radio Glossary (ARRL); 47 CFR 97.119, Station identification (eCFR)

PL-259 and SO-239 UHF connector family

Connectors

The threaded UHF family of coaxial connectors: the PL-259 cable plug and the SO-239 equipment socket. They are the standard connectors at HF and are common at VHF; despite the name, Type N is the better choice above 400 MHz. Outdoors they should be carefully taped or otherwise weatherproofed.

Also written: PL-259, SO-239, PL259, SO239, UHF connector, PL 259, SO 239

Learn more: UHF connectors: PL-259 and SO-239, Connectors and weatherproofing

Also used in: Choosing your first radio

On the exams: T9B07

Related: Type N connector, BNC connector, SMA connector, Coax

Sources: Choosing a Ham Radio (Ham Radio License Manual supplement) (ARRL); 2026-2030 Technician question pool, question T9B07 (NCVEC Question Pool Committee); 2026-2030 Technician question pool, question T9B06 (NCVEC Question Pool Committee); 2026-2030 Technician question pool, question T9B01 (NCVEC Question Pool Committee)

Polarization

Antennas and feed lines

The orientation of a radio wave’s electric field. An antenna parallel to the ground, such as a dipole, produces horizontal polarization; one perpendicular to the ground, such as a quarter-wave vertical, produces vertical polarization. Long-distance CW and SSB on VHF and UHF normally use horizontal polarization.

Also written: horizontal polarization, vertical polarization, circular polarization

Learn more: Polarization

Also used in: How radio signals travel, Antennas and feed lines

On the exams: T3A03, T3A04, T3B02, T9A03, E3B13, E9D02

Related: Vertical antenna, Dipole

Sources: Ham Radio Glossary (ARRL); 2026-2030 Technician question pool, question T3A03 (NCVEC Question Pool Committee)

PRB-1

Rules and licensing

The FCC policy, cited in 47 CFR 97.15(b), that state and local regulation of amateur antenna structures must reasonably accommodate amateur communications and be the minimum practicable regulation for the authority’s legitimate purpose.

Also written: PRB1, antenna zoning, antenna regulations

Learn more: Permits, HOAs and airports

On the exams: E1B07, E1B11

Related: Part 97

Sources: 47 CFR 97.15, Station antenna structures (eCFR)

Q

QRP Low-power operation

Operating

Low-power transmitting, usually taken as less than 5 W on CW and 10 W peak on phone. As a Q signal, QRP means decrease power; QRO means increase power. Band plans list QRP centers of activity on many bands.

Also written: low power, QRP operation

Learn more: Q signals

Also used in: Making your first contact, Operating on HF, Digital modes, Working amateur satellites, Logging and confirming contacts

On the exams: G2D10, G6B03, G8C02

Related: DX

Sources: 2023-2027 General question pool, question G2D10 (NCVEC Question Pool Committee); Choosing a Ham Radio (Ham Radio License Manual supplement) (ARRL); Communicating with Other Hams: Q-Signals (ARRL); IARU Region 2 Band Plan (September 2020) (IARU Region 2)

QSL Confirmation of a contact

Operating

As a Q signal, QSL means I acknowledge receipt. A QSL card is a postcard confirming a contact between two stations, and confirmations can also be made electronically, for example through Logbook of The World. A DX QSL manager handles confirmations for a DX station.

Also written: QSL card, QSL manager, QSLing

Learn more: QSL cards, Logging and QSL cards

Also used in: Your first month on the air, Parks and summits on the air

On the exams: G2C09, E2C05

Related: QSO, LoTW, DX

Sources: 2023-2027 General question pool, question G2C09 (NCVEC Question Pool Committee); Ham Radio Glossary (ARRL); Logbook of The World (ARRL); 2024-2028 Extra question pool, question E2C05 (NCVEC Question Pool Committee)

Question pool

Rules and licensing

All current exam questions for an exam element. Each exam is a question set drawn from the pool.

Also written: pool, question set

Learn more: Exam prep

Related: Exam element, VEC

Sources: 47 CFR 97.3, Definitions (eCFR)

R

RACES Radio Amateur Civil Emergency Service

Public service

A radio service using amateur stations for civil defense communications during local, regional or national emergencies. Stations and operators must be certified by a civil defense organization.

Also written: Radio Amateur Civil Emergency Service

Learn more: RACES

Also used in: Your first month on the air, Rules on the air, Clubs, mentors and nets, Connectors and cables

On the exams: T1A10, T2C04, T2C12, G2B09, G2B11, E1B09, E1B10

Related: ARES

Sources: 47 CFR 97.3, Definitions (eCFR); 47 CFR 97.407, Radio amateur civil emergency service (eCFR)

Radio horizon

Propagation

The distance VHF and UHF signals normally reach. Because the atmosphere bends radio waves slightly, it is about 15 percent farther than the visible horizon.

Also written: line of sight, line-of-sight propagation

Learn more: Line of sight and the radio horizon

Also used in: Making your first contact

On the exams: T3C01, T3C04, T3C11, E3C06

Related: Tropospheric ducting

Sources: 2026-2030 Technician question pool, question T3C11 (NCVEC Question Pool Committee); 2024-2028 Extra question pool, question E3C06 (NCVEC Question Pool Committee)

Repeater

Operating

An amateur station that simultaneously retransmits another station’s signal on a different channel. You transmit on its input frequency and listen on its output frequency.

Also written: repeater station

Learn more: Simplex and repeaters

Also used in: What is amateur radio?, Choosing your first radio, Programming a radio, Rules on the air, Digital modes

On the exams: T1A08, T1A09, T1D07, T1E08, T1F09, T1F10, T2A01, T2A03 and 24 more

Related: Repeater offset, CTCSS, Simplex, Duplex

Sources: 47 CFR 97.3, Definitions (eCFR); Ham Radio Glossary (ARRL)

Repeater offset

Operating

The difference between a repeater’s transmit and receive frequencies. Common offsets are plus or minus 600 kHz on 2 m and plus or minus 5 MHz on 70 cm.

Also written: offset, repeater shift

Learn more: Offsets and their direction, Offsets

On the exams: T2A01, T2A03, T2A07

Related: Repeater, CTCSS

Sources: 2026-2030 Technician question pool, question T2A07 (NCVEC Question Pool Committee); 2026-2030 Technician question pool, question T2A01 (NCVEC Question Pool Committee); 2026-2030 Technician question pool, question T2A03 (NCVEC Question Pool Committee)

Resonance

Electronics

An inductor and capacitor in series or parallel form a resonant, or tuned, circuit. An antenna is resonant at the frequency where its feed point impedance is purely resistive.

Also written: resonant frequency, resonant circuit, tuned circuit

Learn more: Reactance and resonance

Also used in: Choosing your first radio, Antennas and feed lines, Electronics basics

On the exams: T6D08, T6D11, T7C02, T9A05, T9A08, G4C06, G6A11, E5A02 and 7 more

Related: Impedance

Sources: 2026-2030 Technician question pool, question T6D11 (NCVEC Question Pool Committee); Ham Radio Glossary (ARRL)

RTTY Radioteletype

Modes

Narrow-band direct-printing telegraphy, sending text from one teleprinter or computer to another. RTTY sent by audio tones through an SSB transmitter normally uses lower sideband.

Also written: radioteletype, teletype

Learn more: PSK31 and RTTY

Also used in: License classes and privileges, Rules on the air, Operating on HF, How radio signals travel, RF exposure and your station

On the exams: G1E11, G2E01, G2E06, G2E14, G8C13, E1C05

Related: PSK31, FT8

Sources: 47 CFR 97.3, Definitions (eCFR); Ham Radio Glossary (ARRL); 2023-2027 General question pool, question G2E01 (NCVEC Question Pool Committee)

S

S meter

Equipment

A receiver meter that shows received signal strength. One S unit is typically 6 dB, so a signal 20 dB over S9 is 100 times more powerful than one at S9.

Also written: S-meter, S unit, S-unit, S9

Learn more: Decibels

On the exams: G4D04, G4D05, G4D06, G4D07

Related: Decibel, RST

Sources: 2023-2027 General question pool, question G4D04 (NCVEC Question Pool Committee); 2023-2027 General question pool, question G4D06 (NCVEC Question Pool Committee); 2023-2027 General question pool, question G4D05 (NCVEC Question Pool Committee)

Simplex

Operating

Transmitting and receiving on the same frequency, station to station without a repeater. Band plans set aside simplex channels so nearby stations can talk without tying up a repeater.

Also written: simplex operation

Learn more: Simplex and repeaters, 2 m band plan

Also used in: What is amateur radio?, Choosing your first radio, Your first month on the air, Programming a radio, Emergency communications

On the exams: T2A02, T2A11, T2B09, T3C01

Related: Repeater, Repeater offset

Sources: 2026-2030 Technician question pool, question T2A11 (NCVEC Question Pool Committee); 2026-2030 Technician question pool, question T2B09 (NCVEC Question Pool Committee); Ham Radio Glossary (ARRL)

Skip zone

Propagation

The area too far away for ground wave and too close for sky wave, where signals are poor. Scatter can let stations in the skip zone hear each other weakly.

Also written: dead zone

Learn more: Skip, the skip zone and the MUF

Also used in: Operating on HF

On the exams: G3C07, G3C08, G3C09

Related: Skywave, Ground wave

Sources: Ham Radio Glossary (ARRL); 2023-2027 General question pool, question G3C09 (NCVEC Question Pool Committee); 2023-2027 General question pool, question G3C08 (NCVEC Question Pool Committee)

SKYWARN

Public service

A National Weather Service volunteer program of trained severe weather spotters who send timely reports of severe weather to the NWS.

Also written: storm spotter, weather spotter

Learn more: SKYWARN

Also used in: Your first month on the air

Related: ARES

Sources: SKYWARN (National Weather Service)

Solar flux index SFI, the 10.7 cm solar flux

Propagation

A measure of the Sun’s radio emission at a wavelength of 10.7 centimeters. Like the sunspot number, it rises and falls over the roughly 11-year solar cycle.

Also written: SFI, solar flux, F10.7, 10.7 cm flux

Learn more: The Sun drives HF, Propagation conditions

On the exams: G3A05, E3C10

Related: Sunspots, K index, MUF

Sources: 2023-2027 General question pool, question G3A05 (NCVEC Question Pool Committee); Space Weather Glossary (NOAA Space Weather Prediction Center)

Spurious emission

Rules and licensing

An emission outside a transmission’s necessary bandwidth that could be reduced without affecting the information sent. Harmonics, on whole-number multiples of the operating frequency, are a common example.

Also written: spurs, spurious, harmonic, harmonics

Learn more: Low-pass filter designer

Also used in: Building your own gear

On the exams: G8B04, G8B12, G9D11, E1B01, E1C10, E1F11, E4A03, E4D02 and 8 more

Related: Bandwidth, Harmful interference

Sources: 47 CFR 97.3, Definitions (eCFR); Ham Radio Glossary (ARRL)

SSB Single sideband

Modes

A form of amplitude modulation that transmits one sideband, popular for voice on HF. By common practice, lower sideband is used on 160, 75 and 40 m and upper sideband on 20 m and above and on VHF and UHF, and FT8 and similar digital modes use upper sideband.

Also written: single sideband, USB, LSB, upper sideband, lower sideband, sideband

Learn more: Which sideband to use

Also used in: License classes and privileges, Choosing your first radio, Digital modes, Learning Morse code, Working amateur satellites

On the exams: T1B10, T3A03, T4B01, T4B06, T4B10, T7A09, T8A01, T8A03 and 37 more

Related: AM, FM, ALC

Sources: Ham Radio Glossary (ARRL); Choosing a Ham Radio (Ham Radio License Manual supplement) (ARRL); 2023-2027 General question pool, question G2A01 (NCVEC Question Pool Committee); 2023-2027 General question pool, question G2A02 (NCVEC Question Pool Committee); 2023-2027 General question pool, question G2A03 (NCVEC Question Pool Committee); 2023-2027 General question pool, question G2A09 (NCVEC Question Pool Committee); 2023-2027 General question pool, question G2E05 (NCVEC Question Pool Committee)

SSTV Slow-scan television

Modes

A way of sending still pictures over a voice-bandwidth channel. Analog SSTV sends color information as sequential lines. Band plans list SSTV frequencies on several HF bands.

Also written: slow-scan television, slow scan TV

On the exams: E1B02, E2B04, E2B09, E2B10, E2B11, E2B12

Related: SSB

Sources: 2024-2028 Extra question pool, question E1B02 (NCVEC Question Pool Committee); 2024-2028 Extra question pool, question E2B04 (NCVEC Question Pool Committee); Band Plan (ARRL)

Station identification

Rules and licensing

Transmitting your call sign at the end of each communication and at least every 10 minutes during it, by CW or by voice in English, or by RTTY or image when the communication uses that emission. Phonetics are encouraged.

Also written: ID, station ID, identify, identification

Learn more: Station identification

Also used in: Programming a radio, Operating on HF, Digital modes, Learning Morse code, Emergency communications

On the exams: T1A03, T1D11, T1F02, T1F04, T1F05, T2A04, G1D06, G2D09 and 2 more

Related: Call sign, Phonetic alphabet

Sources: 47 CFR 97.119, Station identification (eCFR)

Sunspots

Propagation

Dark spots on the Sun whose number rises and falls over a cycle of about 11 years. More sunspots generally mean a better chance of good propagation on the higher HF bands.

Also written: sunspot number, sunspot cycle, solar cycle, solar maximum, solar minimum

Learn more: The Sun drives HF

Also used in: License classes and privileges

On the exams: T3C09, T3C10, G3A01

Related: Solar flux index, MUF

Sources: Ham Radio Glossary (ARRL); 2023-2027 General question pool, question G3A01 (NCVEC Question Pool Committee)

SWR Standing wave ratio

Antennas and feed lines

A measure of how well a load, such as an antenna, is matched to its feed line; 1:1 is a perfect match. Also called VSWR, the ratio of the highest to the lowest voltage along the line. High SWR increases loss in a lossy feed line, and most solid-state transmitters reduce power as SWR rises to protect their output transistors.

Also written: standing wave ratio, VSWR, voltage standing wave ratio, standing-wave ratio

Learn more: SWR and matching calculator, SWR: what it does and does not tell you

Also used in: Choosing your first radio, Building your own gear, Putting up antennas, Connectors and cables

On the exams: T4A02, T7B04, T7C04, T7C05, T7C06, T7C08, T9B09, T9B12 and 18 more

Related: Antenna tuner, Coax, SWR meter

Sources: 2026-2030 Technician question pool, question T9B12 (NCVEC Question Pool Committee); 2026-2030 Technician question pool, question T7C04 (NCVEC Question Pool Committee); Ham Radio Glossary (ARRL); 2023-2027 General question pool, question G9A02 (NCVEC Question Pool Committee); 2026-2030 Technician question pool, question T7C05 (NCVEC Question Pool Committee)

SWR meter

Equipment

A meter that measures standing wave ratio. A directional wattmeter measures forward and reflected power, from which SWR can be found. Choose one for the frequency and power level you will measure.

Also written: wattmeter, directional wattmeter, power meter

Learn more: SWR and matching calculator

On the exams: T4A02, T7C04, T7C08, G4B10

Related: SWR, Antenna analyzer

Sources: Ham Radio Glossary (ARRL); 2023-2027 General question pool, question G4B10 (NCVEC Question Pool Committee); 2026-2030 Technician question pool, question T4A02 (NCVEC Question Pool Committee)

T

Tropospheric ducting

Propagation

Propagation that regularly allows over-the-horizon VHF and UHF communications to ranges of about 300 miles, caused by temperature inversions in the atmosphere.

Also written: tropo, ducting, tropospheric bending

Learn more: VHF and UHF beyond the horizon

On the exams: T3C06, T3C08

Related: Radio horizon, Sporadic E

Sources: 2026-2030 Technician question pool, question T3C06 (NCVEC Question Pool Committee); 2026-2030 Technician question pool, question T3C08 (NCVEC Question Pool Committee); Ham Radio Glossary (ARRL)

Type N connector

Connectors

A moisture-resistant RF connector usable to 10 GHz. Of the common amateur connectors it is the most suitable above 400 MHz.

Also written: N connector, N-type connector, type N, N type

Learn more: The common RF connectors, Connectors and weatherproofing

Also used in: Choosing your first radio

On the exams: T9B06, G6B07

Related: PL-259 and SO-239, BNC connector, SMA connector

Sources: 2023-2027 General question pool, question G6B07 (NCVEC Question Pool Committee); 2026-2030 Technician question pool, question T9B06 (NCVEC Question Pool Committee)

U

ULS Universal Licensing System

Rules and licensing

The FCC database and filing system for wireless licenses. Your license is granted once it appears in ULS, and anyone can look up a call sign there.

Also written: Universal Licensing System, license search, FCC database

Learn more: Wait for your call sign

Also used in: License classes and privileges, Your first month on the air, Making your first contact, Rules on the air, Logging and confirming contacts

On the exams: T1A05, G1D06

Related: FRN, Call sign

Sources: 47 CFR 97.3, Definitions (eCFR); 2026-2030 Technician question pool, question T1A05 (NCVEC Question Pool Committee); ULS License Search (FCC)

Satellites

A satellite receives on its uplink and transmits on its downlink. In U/V mode the uplink is on 70 cm and the downlink on 2 m. Using too much power on the uplink blocks other users.

Also written: uplink, downlink, U/V mode, V/U mode

Learn more: Uplink, downlink and mode names

Also used in: What is amateur radio?, Choosing your first radio

On the exams: T1E02, T8B02, T8B08, T8B12, E2A04, E2A05, E2A08

Related: Doppler shift, LEO, Linear transponder

Sources: 2026-2030 Technician question pool, question T8B08 (NCVEC Question Pool Committee); 2026-2030 Technician question pool, question T8B02 (NCVEC Question Pool Committee)

UTC Coordinated Universal Time

Operating

Coordinated Universal Time, the internationally agreed standard for world time and the official time of the United States. Amateur schedules give times in UTC, written like 1300z. Daylight saving time changes only local time, so your offset from UTC changes twice a year.

Also written: Coordinated Universal Time, Zulu, Zulu time

Learn more: UTC clock

Also used in: License classes and privileges, Your first month on the air, Operating on HF, Digital modes, Working amateur satellites

On the exams: E1C03, E1C07

Related: LoTW

Sources: UTC(NIST) Time Scale (NIST); Daylight Saving Time Rules (NIST); W1AW Operating Schedule (ARRL)

V

VE Volunteer examiner

Rules and licensing

A licensed amateur accredited by a VEC to give amateur license exams. VEs must be at least 18, and at least three VEs of General class or higher must observe a Technician exam.

Also written: volunteer examiner, VE team

Learn more: Find an exam session

On the exams: G1D02, G1D07, G1D08, G1D10, E1E03, E1E04, E1E05, E1E06 and 4 more

Related: VEC, CSCE

Sources: 47 CFR 97.3, Definitions (eCFR); 2023-2027 General question pool, question G1D07 (NCVEC Question Pool Committee); 2023-2027 General question pool, question G1D10 (NCVEC Question Pool Committee); 2023-2027 General question pool, question G1D04 (NCVEC Question Pool Committee)

VEC Volunteer-examiner coordinator

Rules and licensing

An organization that has an agreement with the FCC to coordinate amateur license exams and accredit volunteer examiners.

Also written: volunteer examiner coordinator

Also used in: How to get your license

On the exams: G1D07, E1E03, E1E04, E1E10

Related: VE, Question pool

Sources: 47 CFR 97.3, Definitions (eCFR); 2024-2028 Extra question pool, question E1E03 (NCVEC Question Pool Committee); 2023-2027 General question pool, question G1D07 (NCVEC Question Pool Committee)

Vertical antenna

Antennas and feed lines

An antenna whose radiating element is vertical, usually with radial wires spread out at or near the ground. A quarter-wave ground-plane vertical radiates equally in all compass directions, and sloping the radials of an elevated ground plane downward is a common way to adjust its feed point impedance.

Also written: quarter-wave vertical, ground-plane antenna, ground plane, radials, vertical

Learn more: Verticals and radials, Quarter-wave verticals, Antenna length calculator

Also used in: Radio waves and the spectrum, Electrical and antenna safety

On the exams: T9A08, G9B02, G9B03, G9B06, E9A10, E9A11, E9D07, E9F05

Related: Dipole, Polarization

Sources: Ham Radio Glossary (ARRL); 2023-2027 General question pool, question G9B03 (NCVEC Question Pool Committee); 2023-2027 General question pool, question G9B02 (NCVEC Question Pool Committee)

VFO Variable frequency oscillator

Equipment

The oscillator circuit in a transceiver that sets the receive and transmit frequency, tuned with the main knob. A dual-VFO feature lets you transmit on one frequency and listen on another.

Also written: variable frequency oscillator, VFO knob, dual VFO

On the exams: T4B02, T7A11, G4A12, E2E11

Related: Split operation, Transceiver

Sources: 2026-2030 Technician question pool, question T7A11 (NCVEC Question Pool Committee); 2026-2030 Technician question pool, question T4B02 (NCVEC Question Pool Committee); 2023-2027 General question pool, question G4A12 (NCVEC Question Pool Committee)

W

Modes

A network of amateur and authorized government stations that provides radio email where the internet is unavailable, using email addresses based on call signs. VARA is a digital protocol used with Winlink.

Also written: Winlink Global Radio Email, radio email, VARA

Learn more: Winlink, Winlink in emergencies

Also used in: What is amateur radio?

On the exams: T2C08, G2E02, G2E03, G2E12, G2E13

Related: Packet radio, ARES

Sources: Winlink Global Radio Email (Winlink); 2026-2030 Technician question pool, question T2C08 (NCVEC Question Pool Committee); 2023-2027 General question pool, question G2E02 (NCVEC Question Pool Committee)

WSPR

Modes

A digital mode in the WSJT-X suite used as a low-power beacon for assessing HF propagation. It does not support keyboard-to-keyboard conversation.

Also written: WSPR beacon

Learn more: Propagation conditions: what is being heard now

Also used in: How radio signals travel

On the exams: G8C02, E2E05

Related: Beacon, FT8

Sources: 2023-2027 General question pool, question G8C02 (NCVEC Question Pool Committee); 2024-2028 Extra question pool, question E2E05 (NCVEC Question Pool Committee); 2026-2030 Technician question pool, question T8D10 (NCVEC Question Pool Committee)

Y

Yagi Yagi antenna

Antennas and feed lines

A directional beam antenna with one driven element about a half wavelength long, a longer reflector behind it and one or more shorter directors in front. A longer boom with more directors gives more gain.

Also written: Yagi-Uda, yagi beam

Learn more: Yagis and other beams

Also used in: Working amateur satellites

On the exams: T9A06, G9C01, G9C02, G9C03, G9C05, G9C07, G9C09, G9C10 and 8 more

Related: Beam antenna, Front-to-back ratio, dBi and dBd

Sources: Ham Radio Glossary (ARRL); 2023-2027 General question pool, question G9C02 (NCVEC Question Pool Committee); 2023-2027 General question pool, question G9C03 (NCVEC Question Pool Committee); 2023-2027 General question pool, question G9C05 (NCVEC Question Pool Committee)

Z